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Article

Effects of Water-Saving and Controlled Drainage Water Management on Growth Indices of Mechanically Transplanted Rice Under Side Deep Fertilization Conditions

by
Ying Wang
1,2,
Qingsheng Liu
1,
Lihong Chen
1,*,
Qilin Lu
1,
Shiwei Li
1,
Neng Hu
1,
Shitong Qiu
1 and
Shufang Wang
1,2
1
College of Water Conservancy, Yunnan Agricultural University, Kunming 650201, China
2
Green Smart Agricultural Field and Carbon Emission Reduction Engineering Research Center of University in Yunnan Province, Kunming 650201, China
*
Author to whom correspondence should be addressed.
Agriculture 2025, 15(8), 803; https://doi.org/10.3390/agriculture15080803
Submission received: 11 March 2025 / Revised: 4 April 2025 / Accepted: 7 April 2025 / Published: 8 April 2025
(This article belongs to the Special Issue The Influence of Light, Temperature and Irrigation on Crop Production and Quality)
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Versions Notes

Abstract

:
This study aimed to improve water use efficiency at side deep fertilization paddy fields and reduce the direct discharge of tailwater from upstream dry-farming into Erhai Lake. Field experiments were conducted at Erhai Lake Basin in 2023 and 2024. In this study, paddies were used as storage basins. Two water managements were set with three replicates: flooding irrigation with deep storage and controlled drainage (CKCD), and water-saving irrigation with deep storage and controlled drainage (CCD). The rice growth indicators were observed. The results show that, in 2023, compared with CKCD, the root volume, root-to-shoot ratio, stem node spacing, stem diameter, plant height, tiller number, leaf area index and yield of CCD increased by 13.6, 19.6, 12.1, 4.1, 9.4, 3.0, 21.9, and 6.5%, respectively. For CCD, the total irrigation amount decreased by 27.3%, while irrigation productivity increased by 46.7%. In 2024, there were similar trends as in 2023. However, the tiller number and leaf area index of CCD decreased by 11 and 1.5%, respectively. Additionally, in CCD, the total irrigation amount decreased 52.5%, and the irrigation productivity increased by 1.4 kg/m3. There were similar regulars in soil temperature and its relationship with other growth indicates in 2023 and 2024. Soil temperature in CCD was generally higher than in CKCD. It positively correlated with stem diameter, but negatively with root volume. Additionally, root volume positively correlated with plant height and dry matter accumulation. Overall, the CCD approach could promote the indices of rice growth, increase the paddy capacity of tailwater storage, and reduce water consumption to further achieve water savings and increased yields.

1. Introduction

In the context of global climate change and population growth, food security has emerged significant challenge for countries around the world. As one of the most important food crops in the world [1,2], improvements in rice yield and quality play crucial roles in ensuring the global food supply [3].
The Erhai Lake Basin is the second-largest freshwater lake basin in Yunnan Province [4]. It is an ecologically fragile region with great economic potential. In recent years, this region has faced issues of water resource shortage and pollution due to climate change and agricultural development [5]. As the main food crop in this region, traditional rice planting involves significant water consumption and nutrient losses, which not only aggravate the shortage of water resources but also cause serious environmental pollution. Researchers have proposed various new rice production technologies to improve the efficiency of water and nitrogen-phosphorus nutrient utilization, including water management, fertilization, and applications. Existing water-saving irrigation techniques for rice mainly include alternate wetting and drying irrigation [6,7], controlled irrigation [8,9], and rain-gathering irrigation [10]. Studies have shown that the application of water-saving irrigation technologies not only promotes water use efficiency but also reduces the risk of nutrient losses [11,12]. Furthermore, less water input can improve soil aeration and promote soil redox properties, promoting root growth and laying the foundation for an increased yield. Li et al. [13] analyzed the effects of water-saving irrigation methods on the root morphology and physiological characteristics of rice. This research shows that water-saving irrigation can improve the root structure, canopy characteristics, and population quality by enhancing root vitality and the photosynthetic rate of sword leaves, thereby effectively increasing rice yield. Cao et al. [14] analyzed the effects of alternate wetting and drying technology on water use efficiency and rice yield. This research shows that, compared to traditional flooding irrigation, alternate wetting and drying technology not only reduces water consumption and improves water use efficiency but also significantly increases the number of effective panicles and yield. Additionally, rice paddies generally have a high water storage space for implementing water-saving irrigation techniques [15].
Researchers have effectively reduced the irrigation quotas and decreased drainage volumes by increasing the upper limit of rainwater storage and extending the residence time of rainwater in the paddy. This approach improves rainwater utilization and achieves the goal of water saving and emission reduction [16,17,18]. Wang et al. [19] explored the synergistic effects between water-saving irrigation and control drainage in rice. This study shows that appropriately increasing the depth of water storage and extending the drainage retention time in paddy fields after rainfall can promote rainwater utilization, reduce drainage, and lower the risk of nitrogen losses. Rice heights, panicle lengths, and yields obtained under water-saving irrigation are better than the values obtained under flooding irrigation.
With high economic development, mechanized farming has become an important way to improve rice production efficiency [20,21]. Particularly, mechanical transplanting has effectively alleviated the labor shortage pressure [22]. Mechanical transplanting improves the uniformity of rice transplants and creates better ventilation and light conditions, thereby increasing the spike formation rate and overall yield [23]. In recent years, side deep fertilization technology for rice has gained widespread attention. This technology involves uniformly applying fertilizers to the root area located 3 to 5 cm below the seedlings side by a transplanter [24]. Compared with the traditional artificial surface application, side deep fertilization could reduce the number of manual operations, improve fertilizer utilization, and minimize losses caused by surface runoff and volatilization [25,26]. Additionally, this technology could promote the absorption of nutrients by rice roots to satisfy the nutrient requirements for rice growth and reduce fertilizer losses. Zhong et al. [27] analyzed the effects of side deep fertilization on nitrogen utilization and ammonia volatilization. This study shows that side deep fertilization technique can reduce ammonia volatilization by 18.6% to 26.9% and improve nitrogen utilization efficiency by 5.7%. Gui et al. [28] found that side deep fertilization could promote dry matter accumulation, leaf area index, and nitrogen accumulation in the later stages of rice growth, thereby increasing yield through increases in the numbers of effective panicles and spikelets.
The above studies have shown that water-saving irrigation technology for rice can help reduce water consumption and improve soil aeration. It also promotes root growth, photosynthesis, dry matter accumulation, and yield improvement. Side deep fertilization could effectively reduce fertilizer losses and increase nutrient utilization efficiency and the root growth of rice. The combination of these two approaches can promote the accumulation of organic matter in soil, promote the soil granular structure, and improve soil aeration and water retention capacity. This in turn supports the survival of rhizosphere microorganisms and strengthens the activity of rice roots.
The planting structure from Cangshan mountain to Erhai Lake primarily follows a “corn–rice” pattern. The rice growth season typically coincides with the rainy season. After rainfall, surface runoff from upstream dry-farming can lead to pollution if it is directly discharged into Erhai Lake. Therefore, this study employs an integrated field experimental approach combining controlled irrigation with upstream dryland agricultural tailwater utilization in rice paddies through side deep fertilization technology. By conceptualizing paddy fields as natural wetland systems, we systematically examine water-saving irrigation with deep storage and controlled drainage (CCD) under side deep fertilization conditions. This research focuses on evaluating CCD’s impacts on multiple rice growth parameters and physiological indicators while elucidating its underlying mechanisms. This innovative approach achieves dual benefits: it effectively recycles stored upstream tailwater to reduce irrigation water extraction from Erhai Lake while simultaneously enhancing root-mediated nutrient and water uptake efficiency. The resultant synergistic effects significantly improve plant developmental processes and ultimately boost grain yield. Our findings provide both theoretical insights and practical applications for sustainable rice cultivation practices in the Erhai Lake Basin, offering science-based solutions for water resource conservation and agricultural productivity enhancement.

2. Materials and Methods

2.1. Description of the Experimental Area

Two-year field experiments were conducted from May to October in 2023 and 2024, respectively, at Gusheng Village Organic Planting Area in Dali (25°48′ N, 100°8′ E), as shown in Figure 1. This area is located in the western region of the Erhai Lake Basin and the altitude is 1972.8 m. It has a mid-subtropical plateau monsoon climate with alternation of wetting and drying. It is mild in four seasons, with a small difference in annual temperature and a large difference in daily temperature. The annual average temperature is 14.8 °C, and the annual average precipitation is 1029 mm. The region practices a “rice in summer–rapeseed in winter” rotation system. The precipitation and daily average temperature during the rice seasons (May to October) in 2023 and 2024 are shown in Figure 2. In 2023, the average temperature during the rice-growing season was 20.3 °C, with 796 mm of precipitation. In 2024, the average temperature during the rice-growing season was 20.4 °C, with 739.8 mm of precipitation (Figure 2b). There were high temperatures and abundant rainfall during this period, providing a favorable growth environment for rice growing. The precipitation during rice growing season in 2023 and 2024 was higher than the daily average value, because most rainfall occurred in August (Figure 2a). During this period, surface runoff from dry-farming was likely to occur while rice was in the panicle initiation stage, heading stage, and flowering stage. Meanwhile, there was a large water storage capacity in the paddies. The water-saving and drainage control pattern employed in this study maintained a lower water layer on the field surface, effectively accumulating rainfall and storing some tailwater from upstream dry-farming areas, thereby reducing the volume discharged directly into Erhai Lake. Before planting, soil profiles were excavated to collect soil samples in different layers. Basic physical and chemical properties were measured. The soil texture is sandy loam. Physical and chemical properties of the topsoil are as follows: a bulk density of the surface of 1.27 g cm−3, soil saturated volumetric water content of 50.7%, pH of 6.7, organic matter content of 68.1 g kg−1, total nitrogen content of 4.3 g kg−1, effective phosphorus content of 68.3 mg kg−1, and available potassium content of 57.5 mg kg−1. From the perspective of soil physicochemical properties, the surface soil exhibited a relatively loose structure, while its higher organic matter content enhanced soil porosity. This improvement in porosity thereby strengthened the water retention capacity of the sandy loam soil, which exerted a beneficial impact on maintaining deeper water layers in the paddy fields during this experiment.

2.2. Experimental Materials

The rice variety was Yunjiang 37. Machine transplanting took place on 20 May 2023 and 26 May 2024, respectively, with a 14 cm plant spacing, 25 cm row spacing, with 5 or 6 seedlings per hole. The rice was harvested on 5 October 2023. The total growth period was 139 days. In 2024, the rice was harvested on October 12th, with a total growth period of 140 days. The total nutrient inputs (N-P2O5-K2O) in 2023 and 2024 were 262-132-150 kg ha−1 and 214-88-147 kg ha−1, respectively. Organic fertilizer as the base fertilization was applied before tilling and incorporated into the plow layer using a rotary tiller. The green intelligent fertilizer was applied using side deep fertilization technology. It was placed into 3 to 5 cm depths of soil during transplanting (Figure 3). Urea as a tillering fertilizer was top-dressed at the end of the recovery stage, and potassium chloride as a panicle fertilizer was applied at the end of the tillering stage. The fertilization schedules are shown in Table 1.

2.3. Experimental Design

The field experiments were conducted from May to October in both 2023 and 2024, with the same fertilization treatments and different water treatments. The treatments involved conventional flooding irrigation, controlled irrigation, and a combination of paddy water storage depth, controlled drainage, and the reuse of tailwater from dry-farming. This established a water-saving and controlled drainage pattern. Specifically, conventional flooding irrigation and controlled irrigation techniques were implemented when there was no precipitation using water from Erhai Lake or reservoir ponds for irrigation. When there was precipitation, the collected precipitation was retained in paddies, and runoff generated from upstream dry-farming was reused for deep storage in paddies (Figure 4). Two levels of the water storage depth were set (1/3 and 1/4 of the rice plant height), resulting in two water management patterns: flooding irrigation with deep storage and controlled drainage (CKCD) and water-saving irrigation with deep storage and controlled drainage (CCD). Each treatment had three replicates in six plots of 320 m2 for each. The indicators for water regulation in different treatments are shown in Table 2, and the regulatory schematic is illustrated in Figure 5. Plastic films between different plots were buried into an 80 cm depth of soil used to prevent lateral seepage. Pest and disease management, as well as weeding, were conducted according to local management standards.

2.4. Observation Index and Methods

(1) Soil data
Soil profiles were excavated using an auger to collect soil samples from different layers before land preparation. The soil samples were then detected in the laboratory to obtain the soil bulk density, pH value, organic matter, total nitrogen content, available phosphorus content, available potassium content, and soil saturation moisture content in the 0–20 cm soil depth.
(2) Meteorological data
Effective rainfall (mm), average temperature (°C), average wind speed (m s−1), and relative humidity (%) were obtained from a meteorological station at the fields.
(3) Irrigation and drainage volumes
Water meters were installed at the inlet and outlet of each plot to measure irrigation and drainage volumes.
(4) Water consumptions
If the water depth was zero, soil moisture was measured daily at 8:00 a.m. by TDR. Based on the root zone observation depths for different growth stages of rice presented in Table 2, the TDR probes were inserted into corresponding soil layers. Readings were recorded after the stabilization of the digital display on the instrument. Three repeated measurements were taken at each fixed observation point, with ten distinct points being systematically monitored within each experimental plot. Otherwise, the water depth was measured by a ruler. The average water depth was calculated according to the values of four fixed points in each plot.
(5) Tillering and heights
During the early tillering stage, tillering and plant heights were observed every 5 days. During the peak tillering stage, they were observed every 2–3 days.
(6) Leaf Area Index (LAI)
At the end of each growth stage, ten leaves in different sizes were selected. A 1 × 1 mm2 grid paper was used to outline the leaf borders. Then, the maximum length and width of the leaves were measured. The actual leaf area was calculated by the correlation between the leaf border and length and width of the leaves. LAI = Total green leaf area/land area.
(7) Dry matter
At the end of each growth stage, five plants were collected from each treatment group. The samples were separated into stems, leaves, panicles, and roots. Then, they were placed in envelopes separately. They were shrank at 105 °C for 30 min and then were dried at 80 °C to a constant weight.
(8) Root-to-shoot ratio (R/S)
At the end of each growth stage, the fresh weights of various parts of the plants were measured. The root-to-shoot ratio was calculated as follows:
R/S = total fresh weight of rice roots/fresh weight of aboveground parts.
(9) Total root volume
The root volume was measured by the Archimedes principle.
(10) Stem node spacing length
Beginning at the panicle initiation stage, the main stem of each plant was selected. The leaves were stripped. Meanwhile, the number of stem nodes and stem node spacing length were measured.
(11) Stem diameter
Stem diameter was measured synchronously with dry matter measurements by Vernier calipers at the thickest tiller of each plant.
(12) Yield
Five days before harvesting, ten holes of rice were selected randomly from each plot for seed testing. Two days before harvesting, an area of 30 m2 (3 m × 10 m) was selected randomly from each plot to measure actual yields after drying the harvested plants.
(13) Soil temperature
Soil temperature was obtained by a soil thermometer that was installed in each plot.

2.5. Statistical Analysis

All data were organized and analyzed by Microsoft Office Excel 2019 and IBM SPSS Statistics 26.0 software. The analysis of significant differences among different treatments was performed by an independent sample t-test. Before the t-test, a homogeneity of variance test was needed. If Sig > 0.05, the variance is homogeneous. If Sig < 0.05, the variance is heterogeneous. Then, a t-test was performed. If Sig < 0.05, the difference between the two samples was significant. If Sig > 0.05, the difference between the two samples was not significant.
OriginPro 2021 (64-bit) 9.8.0.200 software was mainly used for drawing graphs.

3. Results

3.1. Growth and Physiological Indices

3.1.1. Root Volume and Root-to-Shoot Ratio

The root system is a crucial part of the rice plant for the absorption of water and nutrients. It also serves as one of the main pathways for transportation and gas permeability in the plant [29]. The performance of root system plays a vital role in rice growth and yield formation. The root volume and root-to-shoot ratio are important parameters in plant physiology. The root volume directly presents the size and development of the root system [30]. The root-to-shoot ratio reflects the plant’s ability to adapt to its environment and its growth strategy [31]. Both of them indicate the growth balance between the aboveground and underground parts of rice. The changes in the root volume and root-to-shoot ratio of rice during different growth stages in 2023 and 2024 are shown in Figure 6.
The root volume exhibited a unimodal trend in 2023, peaking at the milk-ripe stage before declining during ripening. CCD consistently increased the root volume compared to CKCD (p < 0.05). While the root-to-shoot ratio generally decreased across treatments, CCD maintained higher ratios except during panicle initiation, where CKCD temporarily surpassed CCD, with a more pronounced reduction trend for CCD thereafter.
The observed results can be explained as follows. First, the root volume increases with rice growth due to rising root numbers. However, during the ripening stage, reduced irrigation lowers the soil moisture content, leading to root death and a decreased root volume. Compared to CKCD, the wetting–drying alternation in CCD improves soil aeration and temperature, enhancing root respiration and metabolism [32]. This increases root exudate diversity and quantity, further influencing plant metabolism and growth.
Second, the side deep fertilization technique used in this study avoids fertilizer leaching, improving nutrient absorption and fertilizer use efficiency. Combined water and fertilizer management promotes root growth and physiological activity. During tillering, rice focuses on stem and leaf growth, resulting in a higher root-to-shoot ratio. As growth progresses, nutrients shift to reproductive organs, slowing root growth and reducing the root-to-shoot ratio.
Third, CCD provides better soil temperature and gas permeability conditions than CKCD, supporting root growth and development. This results in a larger root volume and higher root-to-shoot ratios with CCD. In 2023, the root volume and root-to-shoot ratio under CCD were 13.6% and 19.6% higher, respectively, than under CKCD.
In 2024, the variation patterns of the root volume and root-to-shoot ratio in rice were different from those in 2023, and the root volume in 2024 was larger than that in 2023. During the tillering stage and the heading and flowering stage, the root volume in CKCD was significantly higher than that in CCD. While in other periods, the root volume in CCD was significantly higher than that in CKCD. The root volume in CCD showed a decreasing trend during the heading and flowering stage, while it reached its maximum during the ripening stage. The root-to-shoot ratio in the early growth stage was lower than that in 2023, and in the later stages, the root-to-shoot ratios for both years were basically the same. The root-to-shoot ratio in CKCD showed a pattern of first increasing and then decreasing, while the ratio in CCD gradually decreased. In the early stages, the root-to-shoot ratio in CCD was higher than that in CKCD, but in the later stages, it was lower than that in CKCD.
The observed results can be attributed to the following factors. In 2024, higher overall temperatures (Figure 2b) likely accelerated soil microbial metabolic rates, enhancing their growth and activity. Additionally, the preceding crop in 2023 was rapeseed, which has a deeper root system and greater nutrient uptake compared to potatoes in 2024. This difference likely increased residual organic matter and nutrients in the soil, contributing to the larger root volume in 2024.
At the tillering stage, CCD’s controlled irrigation caused roots to grow downward with limited new root formation, resulting in a lower root volume than CKCD. During heading and flowering, rice growth shifted to panicle development, increasing pollen production and the water/nutrient demand, which reduced root growth. Combined with heavy rainfall and dry-farming tailwater recharges, the deeper water layer in CCD led to root discoloration and decay, further decreasing the root volume and root-to-shoot ratio.
Overall, in 2024, the root volume and root-to-shoot ratio with CCD were 8.1% and 14% higher, respectively, than with CKCD.
Above all, under side deep fertilization conditions, the water-saving irrigation with a deep storage and controlled drainage pattern can effectively promote the growth of rice roots. The combination of these two approaches not only promotes the roots’ absorption of nutrients and water but also improves soil moisture content and gas permeability. This, in turn, effectively promotes root respiration and metabolism, promoting a better growth condition for rice.

3.1.2. Stem Node Spacing Length

The stem is one of the main parts of the formation of rice plants. Its growth and development are very important for rice yield and quality [33]. The stem node spacing length and stem diameter are key indicators that can reflect plants’ resistance to lodging and the transportation of nutrients.
The changes in the stem node spacing length of rice during the growth period are shown in Figure 7. As plants grow, stem node numbers and spacing lengths gradually increase.
In 2023, at the panicle initiation stage, the stem node spacing of CKCD was higher than the value of CCD. Particularly, the spacing length of CKCD was significantly higher than the value of CCD at the second and fourth nodes. However, there were no significant differences between the two treatments at the first and third nodes (Figure 7a). At the heading and flowering stage, there were five stem nodes for CCD, while there were four stem nodes for CKCD. The first spacing length of CKCD was greater than the value of CCD, although this difference was not significant. In contrast, the second, third, and fourth spacing lengths of CCD were significantly larger than the values of CKCD (Figure 7b). At the milk-ripe and ripening stages, both treatments had five stem nodes. The spacing lengths of CCD were larger than the values of CKCD (Figure 7b,d). There were significant differences in all nodes between two treatments, except the fifth node (Figure 7c). At the ripening stage, although the spacing lengths of CCD were longer than the values of CKCD, only fifth spacing length showed a significant difference (Figure 7d).
The observed results can be explained as follows. First, in the panicle initiation stage, the deeper water layer in CKCD causes a soil oxygen deficiency, placing plants in a hypoxic environment. This triggers fatigue and the production of growth regulators [34], such as the accumulation of ethylene. These factors promote upward growth and accelerate stem elongation to capture more sunlight, which causes the first and second stem nodes to become elongated.
Second, during the heading and flowering and milk-ripe stages, CCD implements deep rainwater storage and dry-farming tailwater reuse, creating a deeper water layer. This sudden environmental stress induces continuous growth regulator production, prompting stem elongation and forming five stem nodes in CCD compared to four in CKCD.
Third, after the milk-ripe stage, grain formation increases, and CCD’s richer root system absorbs more nutrients and water, enhancing photosynthesis and upward stem growth. By the ripening stage, the limited water supply alters auxin and cytokinin levels, causing CKCD to adjust its metabolism, resulting in reduced stem elongation. Despite this, CKCD’s elongation remains lower than CCD’s.
Overall, in 2023, the spacing length in CCD increased by 12.1% compared to CKCD.
In 2024, the overall spacing length of rice stems was lower than that in 2023. During the panicle initiation stage, the spacing lengths of the second and third nodes in CCD were larger than those in CKCD, although there was no significant difference for the third node. At the heading and flowering stage, the spacing lengths of the first and fifth nodes in CKCD were larger than those in CCD, but there was no significant difference. For the remaining nodes, the internode lengths were significantly greater in CCD compared to CKCD. At the milk-ripe stage, the spacing length of the fifth node in CKCD was significantly greater than that in CCD, while there were no significant differences for the remaining nodes. In the ripening stage, the spacing length of the fourth node in CCD was lower than that in CKCD, while the spacing lengths of the remaining nodes were all higher in CCD. Additionally, the first and fifth nodes of the stems for both treatments passed the significance test.
The reasons for these results above can be summarized as follows. Firstly, due to the lower inputs of nitrogen and phosphorus nutrients in 2024 compared to 2023 (Table 1), the deficiency of these nutrients may have resulted in shorter rice stems, leading to a lower spacing length in 2024.
Secondly, during the heading-flowering and yellow-ripe stages, the increased rainfall during this period provided suitable moisture and temperature conditions for the fields under CCD compared to CKCD. With appropriate moisture levels, plant growth hormones and cell turgor pressure are enhanced, promoting cell expansion and division, which facilitates stem node growth. Consequently, the spacing lengths in CCD were greater than those in CKCD.
Thirdly, however, during the milk-ripe stage, the CCD experienced more instances of dry-farming tailwater recharges than in 2023. Prolonged waterlogging conditions affected the rice roots’ ability to absorb water and nutrients, impacting their supply to the aboveground parts of the plant. As a result, the spacing lengths in CCD were lower than those in CKCD.
Throughout the growth period of 2023, the spacing length in CCD increased by 7.5% compared to CKCD.
Above all, water affects plant auxin levels and cell division by affecting the growth environment of rice, thereby affecting the elongation of stem nodes. Appropriate water management under CCD promoted rice stem growth.

3.1.3. Stem Diameter

The changes in the stem diameter of rice during the growth stages are shown in Figure 8. As plants grew, the stem diameter of rice initially increased and then decreased during the growth stages. In 2023, in the recovery stage, CKCD had a larger stem diameter than CCD, but the difference was not significant. From the tillering stage, CCD had a larger stem diameter than CKCD, yet the difference was not significant. From the panicle initiation to the ripening stage, CCD had a significantly larger stem diameter than CKCD.
The reasons for these results can be summarized as follows. In the recovery stage, seedlings primarily focus on root growth, and stem diameters are smaller. The tillering stage is characterized by rapid nutrient growth as the roots expand, providing substantial nutrition for the development of the stem and leaves and resulting in a notable increase in stem diameter. From the tillering stage, CCD employed water management that combines controlled irrigation with the reuse of tailwater from dry-farming practices. This further promotes root development, enabling the roots to supply more nutrients and water to stems and leaves, and thus promotes stem growth. As a result, the stem diameter in CCD increased by 4.1% compared to CKCD throughout the growth period of 2023.
In 2024, the change in the stem diameter at each growth stage of rice was roughly the same as that in 2023. The stem diameter of CCD was significantly smaller than that of CKCD at the panicle initiation stage, and the stem diameter of CCD was significantly larger than that of CKCD at other growth stages.
The reasons for these results can be summarized as follows. At the panicle initiation stage, when the controlled irrigation was implemented, CCD resulted less moisture in the field compared with CKCD, which led to increased root growth for rice (Figure 6). Under the conditions of a water deficit, stomatal closure affected the absorption of nutrients and water by stems, and so the stem diameter of the CCD treatment group was smaller than that of the CKCD group. As a result, the stem diameter in the CCD group increased by 10.5% compared to the CKCD group throughout the growth period of 2024.
Above all, under side deep fertilization conditions, the water-saving and controlled drainage pattern used in CCD can effectively reduce the loss of water and nutrients so that the plants received sufficient nutrients, promoting the elongation of the stem node spacing and an increase in the stem diameter. This significantly promotes the robustness of the stems and improves the plant’s lodging resistance, thus providing strong support for increased yields in the later growth stages.

3.1.4. Plant Height and Tillering Dynamics

Plant height and the number of tillers are important indicators that reflect the growth status and yield potential of rice [35]. Plant height directly affects the plant’s resistance to fertilizer and lodging. The number of tillers directly influences the number of effective panicles, thus having a direct impact on the final yields.
The dynamics of plant height and number of tillers during the growth period are shown in Figure 9. The variation trends in plant height under the two water management practices were generally consistent, both initially increasing, then decreasing, and eventually stabilizing (Figure 9a). Overall, the plant height under CCD was consistently higher than the value of CKCD, and the peak height under CCD occurred earlier. In 2023, on the whole, the growth rate of plant height in the CCD group was higher than the value of the CKCD group. However, between 35 and 40 days after transplanting, the growth rate of plant height in the CCD group was lower than the value of the CKCD group.
The reasons for these results can be summarized as follows. Under side deep fertilization conditions, the lower irrigation limit of CCD improves fertilizer utilization, promotes soil aeration, promotes root development, and makes the roots more robust and abundant (Figure 6). This provides more water and nutrients for rice plants, promoting the upper growth of plants. At 35 to 40 days after transplantation, higher environmental temperatures (Figure 2b) and a CCD water layer lower than that of CKCD lead to increased transpiration rates of leaves, as well as elevated respiration rates, which consume more organic matter. In this case, the leaves may be curled, which reduce the efficiency of light utilization and negatively affect rice growth. Consequently, the growth rate of plant height under CCD is lower than under CKCD. During the growth period, the height of CCD increased by 9.4% compared to CKCD.
In 2024, the plant height of rice under the two irrigation treatments was alternately leading, but the final value of the CCD treatment group was higher than the CKCD treatment group. In the early stage, the plant height growth rate of the CKCD group was higher than that of the CCD group, but in the later stage, the growth rate of the CCD group was higher than that of the CKCD group. The reasons of these results can be summarized as follows. In the early stage, CCD affected the nutrient absorption of roots by controlling the water supply so that the plant height and its growth rate in the early stage were lower than those in CKCD. In the later stage, rainwater deep storage and tailwater recharge provided suitable water and nutrient supplies for rice, and so the plant height and its growth rate under CCD were higher than those under CKCD treatment. During the growth period of 2024, the plant height of the CCD treatment group increased by 2% compared with the CKCD group.
Under the two water management plans, the tillering dynamics had a similar trend, showing an initial increase followed by a decrease (Figure 9b). The growth rate was larger from the pre-tillering to mid-tillering stages. After reaching the peak in the mid-tillering stage, the growth rate began to decline slowly, and finally the number of tillers remained stable. In 2023, the number of tillers alternated between the two treatments. From 15 to 35 days after transplantation and from 80 days after transplantation to the end of the growth period, the tiller number of CCD was higher than the value of CKCD. However, at other periods, the tiller number of CKCD was higher than the value of CCD.
The results can be explained as follows. Throughout most of the growth period, CCD’s lower irrigation threshold inhibits ineffective tillering. From 15 to 35 days post-transplantation, due to continuous rainfall and lower temperatures, the water layer in CCD becomes deeper than in early stages. In contrast, CKCD’s excessively deep water layer restricts nutrient flow and absorption. CCD maintains a more optimal water depth, promoting tillering and resulting in higher tiller counts compared to CKCD.
When tillering peaks and rice transitions from vegetative to reproductive growth, nutrients shift to reproductive organs. Ineffective tillers, being weaker and shorter, often suffer from light or ventilation deficits, impairing photosynthesis and leading to stunted growth or death. CKCD’s prolonged deep water layer promotes early ineffective tillering, but later tiller mortality reduces its total tiller count below CCD’s.
Overall, in 2023, the CCD’s tiller number increased by 3% compared to CKCD.
In 2024, the final tiller number was higher than that in 2023, and the tiller number of CKCD was always higher than that of CCD. In the early stage, the tiller number of rice under the two treatments was quite different. But, the growth rate of tiller number under CCD was higher than that under CKCD. In the later stage, the tiller number of the two was basically close. The reasons for these results can be summarized as follows. In the early stage, when CCD was implemented with controlled irrigation, the water supply was less than that of CKCD, which inhibited the generation of ineffective tillers of rice to a certain extent. In the later stage, when the dry-farming tailwater was recharged, the corresponding water and nutrient supply in the tailwater were obtained so that the tillering rate was faster. The tiller number of CCD was 11% lower than that of the CKCD treatment during the growth period of 2024.
Above all, under side deep fertilization conditions, the water management in CCD improves fertilizer utilization and promotes the growth of plant height. At the same time, it partially suppresses the formation of ineffective tillers, reducing the waste of nutrients and laying a foundation for increased yields in later stages.

3.1.5. Leaf Area Index and Dry Matter Accumulation

Leaf area index is an important indicator of the photosynthetic capacity of rice. The level of the leaf area index typically reflects a stronger photosynthetic ability and greater biomass accumulation in rice [36]. Additionally, the amount of dry matter accumulation directly affects the biomass and economic yields of rice [37].
The leaf area index and dry matter accumulation of rice during the growth period are shown in Figure 10. As plants grew, the leaf area index showed an initial increase follow by a decrease (Figure 10a,b). In 2023, at the tillering stage, the leaf area index of CKCD was significantly higher than the value of CCD. However, at the panicle initiation stage, the leaf area index of CCD increased markedly, resulting in a significantly higher value than CKCD. From the panicle initiation stage to the ripening stage, the leaf area index of CCD remained significantly higher than the value of CKCD (Figure 10a). In 2024, the leaf area index of CKCD at tillering stage and panicle initiation stage were significantly higher than that of CCD. And, that of CCD from the heading and flowering stage to ripening stage was higher than that of CKCD (Figure 10b).
The reasons for these results can be summarized as follows. At the tillering stage, the CKCD paddy is flooded for a long time, resulting in more ineffective tillers. In contrast, the CCD paddies have better soil permeability, promoting root growth and development, which lead to a significantly lower leaf area index in CCD at the tillering stage. However, since the panicle initiation stage, the CCD group can absorb more water and nutrients from the soil because of its richer and stronger root system, which provides more favorable support for the growth of the aboveground parts of the plant. This ultimately results in a significantly higher leaf area index in the CCD group compared with the CKCD group. However, in 2024, during the panicle initiation stage, CCD implemented controlled irrigation for most of the time. Under conditions of low moisture, the plants closed their stomata to reduce water evaporation. Thus, leaf growth was affected and resulted in a lower leaf area index compared to CKCD. During the growth period of 2023, the leaf area index of CCD increased by 21.9% compared with CKCD. In 2024, the leaf area index of CCD was 1.5% lower than that of CKCD.
The changes in the dry matter accumulation of rice during the growth stages are shown in Figure 10c,d. As plants grew, dry matter accumulation gradually increased. In 2023, at the tillering stage, the dry matter accumulation of the CKCD group was significantly higher than the value of the CCD group. However, from the panicle initiation stage to the milk-ripe stage, the dry matter accumulation of the CCD group was significantly higher than the value of the CKCD group. At the ripening stage, although the dry matter accumulation of the CCD group was greater than the CKCD group, the difference did not reach statistical significance. In 2024, the dry matter accumulation of the CKCD group was significantly higher than that of the CCD group at heading and flowering stage (HFS) and milk-ripe stage (MRS). But, CCD was higher than CKCD treatment at other growth stages.
The reasons for these results can be summarized as follows. In 2023, at the tillering stage, the CKCD paddy was flooded for a long time, resulting in more ineffective tillers, and the plants preferentially grew above ground. As a result, dry matter accumulation in the tillering stage was significantly higher in the CKCD group compared with the CCD group. As plants grow, the ineffective tillers of CKCD gradually disappear, and long-term flooding creates an anaerobic environment. In this anaerobic environment, a series of reductive reactions occur in the soil, leading to the production of toxic substances, such as Fe2⁺, which affects the roots’ ability to absorb nutrients [38]. In contrast, the soil permeability of CCD is better, which promotes the growth and development of rice roots, and could provide more nutrients for plants, thus promoting the upward growth of rice. Additionally, due to the less ineffective tillers of CCD, the rice plants are better adapted to ventilation and light conditions. This leads to an increase in synthesis of photosynthetic products and promotes dry matter accumulation. As a result, the dry matter accumulation of the CCD group is higher than the value of the CKCD group in the later growth stages.
In 2024, during the heading and flowering and milk-ripe stages, there was significant rainfall, leading to a large amount of deep rainwater storage and dry-farming tailwater recharges. This resulted in a deeper water layer compared with CKCD, which caused the soil in the rice fields to become deficient in oxygen, reduced the microbial activity, and slowed down the decomposition of organic matter. These factors negatively impacted root nutrient absorption, thereby affecting dry matter accumulation, resulting in lower dry matter accumulation in the CCD group compared with the CKCD group during this period.
In contrast, during the remaining periods, the appropriate moisture conditions in CCD facilitated the roots’ absorption of nutrients and water, ensuring adequate conditions for photosynthesis and promoting dry matter accumulation, leading to higher dry matter accumulation in the CCD group compared to the CKCD group.
Above all, under side deep fertilization conditions, CCD combines controlled irrigation with the reuse of tailwater from dry-farming practices, and promotes the development of plant roots. This improvement allows the plants to absorb more nutrients from the soil and the tailwater, thus promoting the growth and development of leaves. The increase in the leaf area index promotes the photosynthetic capacity of rice, promoting the synthesis of organic matter and promoting the accumulation of dry matter in rice.

3.2. Correlation Analysis Between Soil Temperature and Various Growth Indices

3.2.1. Soil Temperature

Soil temperature directly affects the growth rate of rice [39]. Within a specific range, higher soil temperatures promote faster plant growth. Furthermore, soil temperature influences the absorption of water and nutrients by rice [40]. It also affects the abundance of microbial communities in the rhizosphere [41]. The abundance and activity of these microbial communities significantly impact the ability of rice roots to absorb water and nutrients, thereby affecting various growth and physiological indicators of the plant.
The changes in soil temperature across different treatments during the growth period are shown in Figure 11. Overall, the soil temperature of CCD was higher than the value of CKCD, and the variation was greater. The fluctuation of soil temperature in 2024 was smaller than that in 2023.
The reasons for these results can be summarized as follows. CCD primarily employs controlled irrigation, which maintains the soil in a moist state for extended periods, resulting in higher soil temperatures. Additionally, the frequent and small amounts of irrigation in CCD create alternate wetting and drying conditions on the soil surface, which affects the fluctuations in soil temperature. Additionally, during the reuse of dry-farming tailwater, the water layer in CCD is higher than the value of CKCD, causing more significant temperature changes over a short period, and temperatures are lower than those in CKCD. Compared with 2023, the temperature fluctuations in 2024 were reduced, coinciding with increased rainfall (Figure 2b). Moreover, the frequency of recharges in 2024 exceeded that of 2023, allowing the paddy field to maintain a water layer for an extended period, which contributed to the smaller temperature fluctuations in 2024 relative to 2023.
These results indicate that soil moisture conditions under different irrigation patterns significantly influence soil temperature. Fields with a prolonged water layer tend to exhibit relatively lower soil temperatures but exhibit smaller rates of temperature change. This aligns with the findings of Yin et al. [42].

3.2.2. Correlation Between Soil Temperature and Various Indices

The correlations between soil temperature and stem diameter and root volume are shown in Figure 12. The soil temperature under different treatments shows a linear positive correlation with stem diameter, while a linear negative correlation is observed between the soil temperature and root volume. Within an appropriate temperature range, the number of tillers and stem diameter increase as the soil temperature rises. Overall, the soil temperature and stem diameter of the CCD group are higher than the values of the CKCD group.
Under prolonged flooding conditions, the change in soil temperature of CKCD is more stable than the value of CCD. As a result, the correlation coefficient is higher for CKCD. When soil temperature is moderate, the activity of microorganisms such as bacteria and fungi in the rhizosphere increases. These microorganisms accelerate the decomposition of organic matter, releasing nutrients and providing more nourishment for rice, which further improves the nutrient supply to the stems and promotes stem diameter growth. As plants grow, the decrease in air temperature leads to a reduction in the soil temperature. However, due to accumulation during earlier stages, the leaves continue to carry out photosynthesis and synthesize organic matter, which also promotes root growth. This leads to a negative correlation between the soil temperature and root volume.
The correlations between root volume and plant height, as well as dry matter accumulation, are shown in Figure 13. Under different treatments, the root volume shows a linear positive correlation with both plant height and dry matter accumulation. As the root volume increases, the plant height and dry matter accumulation of rice also increase. Overall, the root volume, plant height, and dry matter accumulation of the CCD group are higher than values of the CKCD group.
The expansion and development of roots effectively promote the plant’s ability to absorb water and nutrients. Additionally, a larger root volume provides better mechanical support for plants, increasing plant stability. This stability promotes the growth of the aboveground parts of the plant, facilitates photosynthesis, and ultimately promotes the synthesis and accumulation of dry matter.
Above all, under different water management practices, the soil temperatures in the paddies varies. These varying soil temperatures affect indicators such as the number of tillers and stem diameter in rice. Additionally, the size of the root volume influences the plant’s ability to absorb water and nutrients, which in turn affects plant height and dry matter accumulation, ultimately impacting rice yield.

3.3. Yield and Water Productivity

The water productivity of rice is an important indicator for assessing irrigation effectiveness and water-saving potential [43]. The rice yield and water productivity under different water management practices are shown in Table 3. In 2023, compared with CKCD, the total irrigation amount of CCD decreased by 27.3%, the yields increased by 6.5%, and the irrigation productivity increased by 46.7%. In 2024, compared with CKCD, the total irrigation amount of CCD decreased by 52.5%, the yields increased by 3.8%, and the irrigation productivity increased by 1.4 kg/m3.
The reasons for these results can be summarized as follows. For most of the time, CCD employs controlled irrigation, significantly reducing the irrigation volume and evapotranspiration in the paddies. Additionally, its lower irrigation limit provides a higher water storage capacity, allowing for the reuse of more dry-farming tailwater. The yields of each treatment group in 2024 were lower than those in 2023, probably because the total nutrient input in 2024 was lower than that in 2023.
The above results indicate that under side deep fertilization conditions, the combination of controlled irrigation and dry-farming tailwater reuse in CCD not only reduces irrigation water usage but also promotes the ability to capture dry-farming tailwater. This approach improves water productivity and ultimately achieves the goals of water conservation, increased yields, and reduced emissions.

4. Discussion

4.1. Effects of Water-Saving and Controlled Drainage on Growth Indices of Rice Under Side Deep Fertilization Conditions

Water and fertilization management play important roles in rice production. Water conditions can limit the effectiveness of fertilizers, while the availability of nitrogen nutrients can influence the photosynthesis and the physiological processes of water, ultimately affecting water use efficiency [44]. Research by Zhang et al. [45] indicates that under controlled irrigation, applying an appropriate amount of nitrogen fertilizer can promote the net photosynthetic rate and stomatal conductance of rice leaves. However, excessive nitrogen can increase rice’s sensitivity to water stress, which decreases stomatal conductance. Furthermore, research by Yan et al. [46] shows that, compared to traditional flooding irrigation, employing alternate wetting and drying irrigation technology can enhance the rainfall storage capacity of paddy fields. This method improves various indicators, including root length, root biomass, net photosynthetic rate, crop growth rate, nitrogen accumulation, number of tillers, and harvest index. Therefore, appropriate water management in rice production can promote the release of soil nutrients, increase root activity, and promote the absorption and transformation of nutrients and water, ultimately improving rice yields.
The water management approach used in this study incorporates water-saving irrigation with deep storage and controlled drainage. This approach partially creates alternating wet and dry soil conditions, improving soil aeration [47]. Such conditions foster an aerobic environment for rice roots, improving the physiological activity of root nitrogen metabolic enzymes [48]. Additionally, during the wet–dry alternation, water molecules are easily adsorbed in soil aggregates due to capillarity and hydrogen bonding. This process promotes the decomposition of soil organic matter by microorganisms [49], enabling them to break down fertilizers more effectively and release essential nutrients into the soil. As a result, root absorption improves, increasing dry matter accumulation and potentially enhancing rice yields.
In rice production, water management, seedling transplantation and fertilization methods significantly contribute to rice growth. Machine transplantation is a sustainable alternative to manual transplantation and has certain advantages in operational efficiency compared to manual planting [50]. Moreover, machine transplantation guarantees more uniform spacing between plants, which promotes ventilation and light exposure, thereby improving leaf growth and promoting photosynthesis. Research by Hossen et al. [51] indicates that machine transplantation provides an optimal planting depth and density for rice seedlings, increasing their survival rate and ultimately increasing rice yields. Additionally, side deep fertilization is an innovative method that applies fertilizers deep into the soil near the rice roots during machine transplantation. This technique guarantees close contact between nutrients and rice root systems, increasing the concentration of nutrients in the rhizosphere [52] and promoting the growth of beneficial microorganisms such as nitrogen-fixing bacteria, phosphate-solubilizing bacteria, and root-promoting bacteria, which promotes the decomposition of organic matter in the soil, thereby strengthening the roots’ ability to absorb water and nutrients. Research by Chatterjee et al. [53] indicates that side deep fertilization technique allows nitrogen to remain in the soil longer in the form of non-exchangeable ammonium (NH4+), thus supporting nutrient availability during the rice growing season.
The above results indicate that adopting water-saving irrigation with deep storage and a controlled drainage pattern under side deep fertilization conditions promotes root absorption of nutrients and water, improving various growth and physiological indicators of rice and ultimately increasing rice yields. In this study, soil temperature shows a negative correlation with the root volume. This negative correlation may be primarily due to lower soil temperatures in the later stages, which can hinder microbial activity. However, methods such as side deep fertilization and tailwater reuse can provide better access to nutrients for the root system. Additionally, tailwater contains certain nutrients such as nitrogen, phosphorus, and potassium, as well as microbial communities [54]. These microorganisms can decompose the nutrients in both tailwater and soil to synthesize organic matter, thereby promoting rice growth and grain filling and ultimately increasing rice yields.
Although the water-saving irrigation with deep storage and controlled drainage pattern has a positive impact on the growth physiology of rice under side deep fertilization conditions, this study also requires further investigation into the mechanism by which this pattern affects agricultural non-point source pollution.

4.2. Effects of Water-Saving and Controlled Drainage on Water Resource Utilization Under Side Deep Fertilization Conditions

Nutrients and water interact with each other, and excessive fertilization can lead to increased water consumption during the early growth stages of rice. Under side deep fertilization conditions, rice roots develop well and have a strong ability to absorb both water and nutrients. Therefore, in situations with limited water resources, roots can absorb moisture from deeper soil layers, which helps reduce irrigation water usage.
Compared with traditional flooding irrigation, water-saving irrigation technology reduces water consumption in the paddy while improving the efficiency of water and nitrogen utilization [55]. Research by Chaurasiya et al. [56] indicates that compared with conventional flooding irrigation, water-saving irrigation technology reduces irrigation water usage by 26% to 52%, improving water resource utilization while maintaining rice yields. Additionally, research by Yan et al. [46] indicates that utilizing an alternate wetting and drying technique to increase the rainfall retention capacity of the paddy reduces the number of irrigation events by three to four times and decreases total irrigation amount by 41.6% to 45.6%.
The water-saving irrigation with deep storage and controlled drainage pattern employed in this study integrates controlled irrigation technology, deep rainwater storage, and dry-farming tailwater reuse. This controlled irrigation not only reduces irrigation water, seepage, and evapotranspiration but also provides a larger water retention capacity for the paddy. Moreover, utilizing deep rainwater storage and reusing dry-farming tailwater in the paddy promotes rainwater utilization and further reduces water resource consumption, thereby improving water resource efficiency.
The above results indicate that under side deep fertilization conditions, adopting water-saving irrigation with a deep storage and controlled drainage pattern can reduce the total irrigation water usage and improve water resource utilization. However, due to the shallow groundwater depth in the Erhai Lake Basin, future research can further explore the influence of groundwater on the growth and physiological indicators of rice under side deep fertilization conditions with this water-saving pattern.

5. Conclusions

At the Erhai Lake Basin, the implementation of the water-saving irrigation with deep storage and controlled drainage water management (CCD) under side deep fertilization conditions for machine-transplanted rice can guarantee high rice yields and improve water productivities.
The CCD pattern significantly improves the growth indicators of rice, such as the root volume, root-to-shoot ratio, stem node spacing, stem diameter, leaf area index, and yield.
The soil temperatures in the CCD pattern are higher than the value of the CKCD pattern. There is a linear positive correlation between the soil temperature and stem diameter, while there is a linear negative correlation between the soil temperature and root volume. Additionally, the root volume has a linear positive correlation with plant heights and dry matter accumulation.

Author Contributions

All authors contributed to the study conception and design. Y.W.: data curation, investigation, methodology, project administration, writing—original draft. Q.L. (Qingsheng Liu) and L.C.: conceptualization, funding acquisition, investigation, methodology, project administration, supervision, writing—review and editing. Q.L. (Qilin Lu), S.L., N.H., S.Q. and S.W.: writing—review and editing. All authors have read and agreed to the published version of the manuscript.

Funding

This work was supported by the Major Science and Technology Projects of the Yunnan Provincial Department of Science and Technology (202202AE090034), the Joint Special Project for Agricultural of Yunnan Province (202401BD070001-062), the Yunnan Talent Support Program (XDYC-QNRC-2022-0107), and the Joint Special Project for Agriculture of Yunnan Province (202101BD070001-121).

Institutional Review Board Statement

Not applicable.

Data Availability Statement

The data presented in this study are available upon request from the corresponding author.

Acknowledgments

We would like to thank all the members who participated in these experiments, and we appreciate the resources provided by our teachers. We also thank the anonymous reviewers and the editor for their suggestions, which substantially improved the manuscript.

Conflicts of Interest

The authors declare no conflicts of interest.

References

  1. Yu, Q.; Dai, Y.; Wei, J.; Wang, J.; Liao, B.; Cui, Y. Rice yield and water productivity in response to water-saving irrigation practices in China: A meta-analysis. Agric. Water Manag. 2024, 302, 109006. [Google Scholar] [CrossRef]
  2. Li, S.-h.; Yang, C.-h.; Yi, X.-x.; Zheng, F.-x.; Du, X.-z.; Sheng, F. Influence of γ-PGA on greenhouse gas emissions and grain yield from paddy rice under different rice varieties. Sci. Total Environ. 2024, 948, 174649. [Google Scholar] [CrossRef]
  3. Liu, W.; Yao, B.; Xu, Y.; Dai, S.; Wang, M.; Ma, J.; Ye, Z.; Liu, D. Biogas digestate as a potential nitrogen source enhances soil fertility, rice nitrogen metabolism and yield. Field Crops Res. 2024, 318, 109568. [Google Scholar] [CrossRef]
  4. Zou, T.; Meng, F.; Zhou, J.; Ying, H.; Liu, X.; Hou, Y.; Zhao, Z.; Zhang, F.; Xu, W. Quantifying nitrogen and phosphorus losses from crop and livestock production and mitigation potentials in Erhai Lake Basin, China. Agric. Syst. 2023, 211, 103745. [Google Scholar] [CrossRef]
  5. Zhao, H.; Wang, Y.; Dong, Y.; He, Z.; Wang, P.; Zheng, H.; He, J.; Zeng, W. Modeling the response of agricultural non-point source pollution to planting structure and fertilization level in Erhai Lake Basin under low-latitude plateau climate. Ecol. Indic. 2023, 154, 110829. [Google Scholar] [CrossRef]
  6. Wang, H.; Zhang, Y.; Zhang, Y.; McDaniel, M.D.; Sun, L.; Su, W.; Fan, X.; Liu, S.; Xiao, X. Water-saving irrigation is a ‘win-win’ management strategy in rice paddies–With both reduced greenhouse gas emissions and enhanced water use efficiency. Agric. Water Manag. 2020, 228, 105889. [Google Scholar] [CrossRef]
  7. Cheng, H.; Shu, K.; Zhu, T.; Wang, L.; Liu, X.; Cai, W.; Qi, Z.; Feng, S. Effects of alternate wetting and drying irrigation on yield, water and nitrogen use, and greenhouse gas emissions in rice paddy fields. J. Clean. Prod. 2022, 349, 131487. [Google Scholar] [CrossRef]
  8. Jiang, Z.; Yang, S.; Smith, P.; Abdalla, M.; Pang, Q.; Xu, Y.; Qi, S.; Hu, J. Development of DNDC-BC model to estimate greenhouse gas emissions from rice paddy fields under combination of biochar and controlled irrigation management. Geoderma 2023, 433, 116450. [Google Scholar] [CrossRef]
  9. Zhu, K.; Zhou, T.; Li, Z.; Zhang, W.; Wang, Z.; Gu, J.; Yang, J. Controlled irrigation can mitigate the greenhouse effects of rice paddy fields with long-term straw return and stimulate microbial necromass carbon accumulation. Field Crops Res. 2024, 317, 109571. [Google Scholar] [CrossRef]
  10. Zhuang, Y.; Zhang, L.; Li, S.; Liu, H.; Zhai, L.; Zhou, F.; Ye, Y.; Ruan, S.; Wen, W. Effects and potential of water-saving irrigation for rice production in China. Agric. Water Manag. 2019, 217, 374–382. [Google Scholar] [CrossRef]
  11. Chen, P.; Xu, J.; Zhang, Z.; Nie, T. ‘Preferential’ ammonium uptake by rice does not always turn into higher N recovery of fertilizer sources under water-saving irrigation. Agric. Water Manag. 2022, 272, 107867. [Google Scholar] [CrossRef]
  12. Ali, M.A.; Hassan, M.R.; Islam, Z.A.; Barman, S.C.; Khan, B.; Khatun, R.; Hiya, H.J.; Islam, M.T. Development of Environment Friendly Paddy Ecosystem for Sustainable Rice Farming through Soil Amendments with Biochar and Alternate Wetting-Drying Irrigations. Am. J. Clim. Chang. 2021, 10, 581–596. [Google Scholar] [CrossRef]
  13. Li, T.; Feng, Y.; Zhu, A.; Huang, J.; Wang, H.; Li, S.; Liu, K.; Peng, R.; Zhang, H.; Liu, L. Effects of Main Water-saving Irrigation Methods on Morphological and Physiological Traits of Rice Roots. Chin. J. Rice Sci. 2019, 33, 293–302. (In Chinese) [Google Scholar] [CrossRef]
  14. Cao, X.C.; Wu, L.L.; Lu, R.H.; Zhu, L.F.; Zhang, J.H.; Jin, Q.Y. Irrigation and fertilization management to optimize rice yield, water productivity and nitrogen recovery efficiency. Irrig. Sci. 2021, 39, 235–249. [Google Scholar] [CrossRef]
  15. Wang, Z.; Shao, G.; Lu, J.; Zhang, K.; Gao, Y.; Ding, J. Effects of controlled drainage on crop yield, drainage water quantity and quality: A meta-analysis. Agric. Water Manag. 2020, 239, 106253. [Google Scholar] [CrossRef]
  16. Yu, S.; Li, S.; Gao, S.; Wang, M.; Meng, J.; Tang, S. Effect of controlled irrigation and drainage on water saving, nitrogen and phosphorus loss reduction with high yield in paddy field. Trans. Chin. Soc. Agric. Eng. 2018, 34, 128–136. (In Chinese) [Google Scholar]
  17. Xiao, M.H.; Hu, X.J.; Chu, L.L. Experimental study on water-saving and emission-reduction effects of controlled drainage technology. Water Sci. Eng. 2015, 8, 7. [Google Scholar] [CrossRef]
  18. He, Y.; Jianyun, Z.; Shihong, Y.; Dalin, H.; Junzeng, X. Effect of controlled drainage on nitrogen losses from controlled irrigation paddy fields through subsurface drainage and ammonia volatilization after fertilization. Agric. Water Manag. 2019, 221, 231–237. [Google Scholar] [CrossRef]
  19. Wang, K.; Yuan, X.; Cao, X.; Gao, Z.; Jiang, S.; Li, J.; Wang, Y. Variation in Paddy Soil Nitrogen as Impacted by Combination of Deep Rainfall Storage and Controlled Drainage. J. Irrig. Drain. 2022, 41, 40–48. (In Chinese) [Google Scholar] [CrossRef]
  20. Li, L.; Wang, Y.; Nie, L.; Ashraf, U.; Wang, Z.; Zhang, Z.; Wu, T.; Tian, H.; Hamoud, Y.A.; Tang, X.; et al. Deep placement of nitrogen fertilizer increases rice yield and energy production efficiency under different mechanical rice production systems. Field Crops Res. 2022, 276, 108359. [Google Scholar] [CrossRef]
  21. Chen, L.; Yi, Y.; Wang, W.; Zeng, Y.; Tan, X.; Wu, Z.; Chen, X.; Pan, X.; Shi, Q.; Zeng, Y. Innovative furrow ridging fertilization under a mechanical direct seeding system improves the grain yield and lodging resistance of early indica rice in South China. Field Crops Res. 2021, 270, 108184. [Google Scholar] [CrossRef]
  22. Shan, S.; Jiang, P.; Fang, S.; Cao, F.; Zhang, H.; Chen, J.; Yin, X.; Tao, Z.; Lei, T.; Huang, M.; et al. Printed sowing improves grain yield with reduced seed rate in machine-transplanted hybrid rice. Field Crops Res. 2020, 245, 107676. [Google Scholar] [CrossRef]
  23. Cheng, S.; Xing, Z.; Tian, C.; Liu, M.; Feng, Y.; Zhang, H. Optimized tillage methods increase mechanically transplanted rice yield and reduce the greenhouse gas emissions. J. Integr. Agric. 2024, 23, 1150–1163. [Google Scholar] [CrossRef]
  24. Zhong, X.; Peng, J.; Kang, X.; Wu, Y.; Luo, G.; Hu, W.; Zhou, X. Optimizing agronomic traits and increasing economic returns of machine-transplanted rice with side-deep fertilization of double-cropping rice system in southern China. Field Crops Res. 2021, 270, 108191. [Google Scholar] [CrossRef]
  25. Zhao, C.; Huang, H.; Qian, Z.-h.; Jiang, H.-x.; Liu, G.-m.; Xu, K.; Hu, Y.-j.; Dai, Q.-g.; Huo, Z.-y. Effect of side deep placement of nitrogen on yield and nitrogen use efficiency of single season late japonica rice. J. Integr. Agric. 2021, 20, 1487–1502. [Google Scholar] [CrossRef]
  26. Liu, T.Q.; Fan, D.J.; Zhang, X.X.; Chen, J.; Li, C.F.; Cao, C.G. Deep placement of nitrogen fertilizers reduces ammonia volatilization and increases nitrogen utilization efficiency in no-tillage paddy fields in central China. Field Crops Res. 2015, 184, 80–90. [Google Scholar] [CrossRef]
  27. Zhong, X.; Zhou, X.; Fei, J.; Huang, Y.; Wang, G.; Kang, X.; Hu, W.; Zhang, H.; Rong, X.; Peng, J. Reducing ammonia volatilization and increasing nitrogen use efficiency in machine-transplanted rice with side-deep fertilization in a double-cropping rice system in Southern China. Agric. Ecosyst. Environ. 2021, 306, 107183. [Google Scholar] [CrossRef]
  28. Gui, R.; Wang, Z.; Pan, S.; Zhang, M.; Tang, X.; Mo, Z. Effects of Nitrogen-Reducing Side Deep Application of Liquid Fertilizer at Tillering Stage on Yield and Nitrogen Utilization of Fragrant Rice. Sci. Agric. Sin. 2022, 55, 1529–1545. (In Chinese) [Google Scholar]
  29. Ding, H.; Jiang, Y.; Cao, C. Deep rice root systems reduce methane emissions in rice paddies. Plant Soil 2021, 468, 337–352. [Google Scholar] [CrossRef]
  30. Liao, S.; Deng, F.; Zhou, W.; Wang, L.; Li, W.; Hu, H.; Pu, S.-l.; Li, S.-x.; Chen, Y.; Tao, Y.-f.; et al. Polypeptide urea increases rice yield and nitrogen use efficiency through root growth improvement. Field Crops Res. 2024, 313, 109415. [Google Scholar] [CrossRef]
  31. Xu, G.-w.; Lu, D.-K.; Wang, H.-Z.; Li, Y. Morphological and physiological traits of rice roots and their relationships to yield and nitrogen utilization as influenced by irrigation regime and nitrogen rate. Agric. Water Manag. 2018, 203, 385–394. [Google Scholar] [CrossRef]
  32. Lan, C.; Zou, J.; Xu, H.; Qin, B.; Li, J.; Chen, T.; Weng, P.; Lin, W.; Shen, L.; Wang, W.; et al. Enhanced strategies for water and fertilizer management to optimize yields and promote environmental sustainability in the mechanized harvesting of ratoon rice in Southeast China. Agric. Water Manag. 2024, 302, 108956. [Google Scholar] [CrossRef]
  33. Shao, Z.; Gu, J.; He, L.; Xu, Y.; Shang, B.; Feng, Z. Effects of elevated ozone, warming, and their interactions on the stem lodging resistance of rice under fully open-field conditions. Agric. Ecosyst. Environ. 2024, 376, 109249. [Google Scholar] [CrossRef]
  34. Sasi, M.; Awana, M.; Samota, M.K.; Tyagi, A.; Kumar, S.; Sathee, L.; Krishnan, V.; Praveen, S.; Singh, A. Plant growth regulator induced mitigation of oxidative burst helps in the management of drought stress in rice (Oryza sativa L.). Environ. Exp. Bot. 2021, 185, 104413. [Google Scholar] [CrossRef]
  35. Zhang, X.; Xing, R.; Ding, Y.; Yu, J.; Wang, R.; Li, X.; Yang, Z.; Zhuang, L. Overexpression of gibberellin 2-oxidase 4 from tall fescue affected plant height, tillering and drought tolerance in rice. Environ. Exp. Bot. 2023, 205, 105118. [Google Scholar] [CrossRef]
  36. Fukuda, S.; Koba, K.; Okamura, M.; Watanabe, Y.; Hosoi, J.; Nakagomi, K.; Maeda, H.; Kondo, M.; Sugiura, D. Novel technique for non-destructive LAI estimation by continuous measurement of NIR and PAR in rice canopy. Field Crops Res. 2021, 263, 108070. [Google Scholar] [CrossRef]
  37. Huang, M.; Tao, Z.; Lei, T.; Cao, F.; Chen, J.; Yin, X.; Zou, Y.; Liang, T. Improving lodging resistance while maintaining high grain yield by promoting pre-heading growth in rice. Field Crops Res. 2021, 270, 108212. [Google Scholar] [CrossRef]
  38. Shao, G.C.; Deng, S.; Liu, N.; Yu, S.E.; Wang, M.H.; She, D.L. Effects of controlled irrigation and drainage on growth, grain yield and water use in paddy rice. Eur. J. Agron. 2014, 53, 1–9. [Google Scholar] [CrossRef]
  39. Hou, R.-j.; Li, T.-x.; Fu, Q.; Liu, D.; Li, M.; Zhou, Z.-q.; Yan, J.-w.; Zhang, S. Research on the distribution of soil water, heat, salt and their response mechanisms under freezing conditions. Soil Tillage Res. 2020, 196, 104486. [Google Scholar] [CrossRef]
  40. Tian, Y.; Shi, C.; Malo, C.U.; Kengdo, S.K.; Heinzle, J.; Inselsbacher, E.; Ottner, F.; Borken, W.; Michel, K.; Schindlbacher, A. Long-term soil warming decreases microbial phosphorus utilization by increasing abiotic phosphorus sorption and phosphorus losses. Nat. Commun. 2023, 14, 864. [Google Scholar] [CrossRef]
  41. Munir, R.; Jan, M.; Muhammad, S.; Afzal, M.; Jan, N.; Yasin, M.U.; Munir, I.; Iqbal, A.; Yang, S.; Zhou, W.; et al. Detrimental effects of Cd and temperature on rice and functions of microbial community in paddy soils. Environ. Pollut. 2023, 324, 121371. [Google Scholar] [CrossRef]
  42. Yin, Z.; Ma, L.; Li, Z.; Feng, H.; Jiang, X. Impact of high temperature on soil water, heat and salt in purple paddy fields under different tillage patterns. Acta Prataculturae Sin. 2024, 33, 80–91. (In Chinese) [Google Scholar]
  43. Johnson, J.-M.; Becker, M.; Dossou-Yovo, E.R.; Saito, K. Improving rice yield and water productivity in dry climatic zones of West Africa: Season-specific strategies. Field Crops Res. 2024, 316, 109519. [Google Scholar] [CrossRef]
  44. Pang, G.; Xu, Z.; Yang, S.; Xu, J. Influence Factors Analysis of Rice Leaf Water Use Efficiency under Controlled Irrigation. Trans. Chin. Soc. Agric. Mach. 2017, 48, 233–241. (In Chinese) [Google Scholar]
  45. Zhang, Z.; Chen, P.; Zheng, E.; Nie, T.; Chen, S.; Li, W. Effect of Different Water and Nitrogen Managements on Rice Leaf Water Use Efficiency Based on Δ13C. Trans. Chin. Soc. Agric. Mach. 2018, 49, 303–312. (In Chinese) [Google Scholar]
  46. Yan, J.; Wu, Q.; Qi, D.; Zhu, J. Rice yield, water productivity, and nitrogen use efficiency responses to nitrogen management strategies under supplementary irrigation for rain-fed rice cultivation. Agric. Water Manag. 2022, 263, 107486. [Google Scholar] [CrossRef]
  47. Majumdar, A.; Dubey, P.K.; Giri, B.; Moulick, D.; Srivastava, A.K.; Roychowdhury, T.; Bose, S.; Jaiswal, M.K. Combined effects of dry-wet irrigation, redox changes and microbial diversity on soil nutrient bioavailability in the rice field. Soil Tillage Res. 2023, 232, 105752. [Google Scholar] [CrossRef]
  48. Alhaj Hamoud, Y.; Shaghaleh, H.; Guo, X.; Zhang, K. pH-responsive/sustained release nitrogen fertilizer hydrogel improves yield, nitrogen metabolism, and nitrogen use efficiency of rice under alternative wetting and moderate drying irrigation. Environ. Exp. Bot. 2023, 211, 105376. [Google Scholar] [CrossRef]
  49. Akter, J.; Islam, M.T.; Jahan, N.; Rahman, M.M.; Amin, M.G.M.; Hossain, M.T.; Adham, A.K.M. Impact of dairy wastewater on paddy rice cultivation, leachate microbes, and soil health under alternate wetting and drying irrigation. Paddy Water Environ. 2025, 23, 179–195. [Google Scholar] [CrossRef]
  50. Lyu, T.; Shen, J.; Ma, J.; Ma, P.; Yang, Z.; Dai, Z.; Zheng, C.; Li, M. Hybrid rice yield response to potted-seedling machine transplanting and slow-release nitrogen fertilizer application combined with urea topdressing. Crop J. 2021, 9, 915–923. [Google Scholar] [CrossRef]
  51. Hossen, M.A.; Hossain, M.M.; Haque, M.E.; Bell, R.W. Transplanting into non-puddled soils with a small-scale mechanical transplanter reduced fuel, labour and irrigation water requirements for rice (Oryza sativa L.) establishment and increased yield. Field Crops Res. 2018, 225, 141–151. [Google Scholar] [CrossRef]
  52. Zhang, M.; Yao, Y.; Zhao, M.; Zhang, B.; Tian, Y.; Yin, B.; Zhu, Z. Integration of urea deep placement and organic addition for improving yield and soil properties and decreasing N loss in paddy field. Agric. Ecosyst. Environ. 2017, 247, 236–245. [Google Scholar] [CrossRef]
  53. Chatterjee, D.; Mohanty, S.; Guru, P.K.; Swain, C.K.; Tripathi, R.; Shahid, M.; Kumar, U.; Kumar, A.; Bhattacharyya, P.; Gautam, P. Comparative assessment of urea briquette applicators on greenhouse gas emission, nitrogen loss and soil enzymatic activities in tropical lowland rice. Agric. Ecosyst. Environ. 2017, 252, 178–190. [Google Scholar] [CrossRef]
  54. Yang, F.; Zhang, X.; Li, J.; Zhao, H.; Jin, F.; Zhou, B. Analysis and evaluation of the treatment and reuse of tailwater: A case study in Erhai Lake. J. Clean. Prod. 2021, 327, 129435. [Google Scholar] [CrossRef]
  55. Crézé, C.M.; Madramootoo, C.A. Water table management and fertilizer application impacts on CO2, N2O and CH4 fluxes in a corn agro-ecosystem. Sci. Rep. 2019, 9, 2692. [Google Scholar] [CrossRef]
  56. Chaurasiya, A.; Dutta, S.K.; Singh, A.K.; Kumar, S.; Kohli, A.; Homa, F.; Kumar, A.; Gathala, M.K.; Laing, A.M. Layering smart management practices to sustainably maintain rice yields and improve water use efficiency in eastern India. Field Crops Res. 2022, 275, 108341. [Google Scholar] [CrossRef]
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Figure 1. Site location (Gusheng Village, China).
Figure 1. Site location (Gusheng Village, China).
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Figure 2. Precipitation in the rice season (May to October), precipitation and daily average temperature during the rice growth periods in 2023 and 2024 (Gusheng Village, China). (a) Precipitation during the rice season (May to October); (b) precipitation and daily average temperature during the rice growth periods in 2023 and 2024.
Figure 2. Precipitation in the rice season (May to October), precipitation and daily average temperature during the rice growth periods in 2023 and 2024 (Gusheng Village, China). (a) Precipitation during the rice season (May to October); (b) precipitation and daily average temperature during the rice growth periods in 2023 and 2024.
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Figure 3. Schematic diagram of side deep fertilization technology for rice.
Figure 3. Schematic diagram of side deep fertilization technology for rice.
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Figure 4. Schematic diagram of water regulations and reductions of emission (Gusheng Village, China).
Figure 4. Schematic diagram of water regulations and reductions of emission (Gusheng Village, China).
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Figure 5. Schematic diagram of water regulations. RS, Pre-TS, Mid-TS, Post-TS, PIS, HFS, and MRS represent recovery, pre-tillering, mid-tillering, post-tillering, panicle initiation, heading and flowering, and milk-ripe stages, respectively. I, P, TR, and H represent irrigation, precipitation, tailwater reuse, and plant height, respectively.
Figure 5. Schematic diagram of water regulations. RS, Pre-TS, Mid-TS, Post-TS, PIS, HFS, and MRS represent recovery, pre-tillering, mid-tillering, post-tillering, panicle initiation, heading and flowering, and milk-ripe stages, respectively. I, P, TR, and H represent irrigation, precipitation, tailwater reuse, and plant height, respectively.
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Figure 6. Root volume and root-to-shoot ratio at each growth stage. TS, PIS, HFS, MRS, and RS represent the tillering stage, panicle initiation stage, heading and flowering stage, milk-ripe stage, and ripening stage. “*” indicates that the significance test at the 0.05 level passed. “**” indicate that the significance test at 0.01 level passed.
Figure 6. Root volume and root-to-shoot ratio at each growth stage. TS, PIS, HFS, MRS, and RS represent the tillering stage, panicle initiation stage, heading and flowering stage, milk-ripe stage, and ripening stage. “*” indicates that the significance test at the 0.05 level passed. “**” indicate that the significance test at 0.01 level passed.
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Figure 7. Stem node spacing at different stages. (a–d) represent the stem node spacing during the panicle initiation stage, heading and flowering stage, milk-ripe stage, and ripening stage, respectively. “*” and “**” indicate that significance test at 0.05 and 0.01 levels passed, respectively. “n.s” indicates that the differences between treatments are not significant.
Figure 7. Stem node spacing at different stages. (a–d) represent the stem node spacing during the panicle initiation stage, heading and flowering stage, milk-ripe stage, and ripening stage, respectively. “*” and “**” indicate that significance test at 0.05 and 0.01 levels passed, respectively. “n.s” indicates that the differences between treatments are not significant.
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Figure 8. Stem diameters at different stages of growth. RS, TS, PIS, HFS, MRS, and RIS represent the recovery stage, tillering stage, panicle initiation stage, heading and flowering stage, milk-ripe stage, and ripening stage. “*” indicates that the significance test at the 0.05 level passed. “**” indicate that the significance test at 0.01 level passed. “n.s” indicates that the differences between treatments are not significant.
Figure 8. Stem diameters at different stages of growth. RS, TS, PIS, HFS, MRS, and RIS represent the recovery stage, tillering stage, panicle initiation stage, heading and flowering stage, milk-ripe stage, and ripening stage. “*” indicates that the significance test at the 0.05 level passed. “**” indicate that the significance test at 0.01 level passed. “n.s” indicates that the differences between treatments are not significant.
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Figure 9. Dynamics of plant height and tillering. (a) Plant height dynamics; (b) tillering dynamics.
Figure 9. Dynamics of plant height and tillering. (a) Plant height dynamics; (b) tillering dynamics.
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Figure 10. Dynamic changes in the leaf area index and dry matter accumulation. TS, PIS, HFS, MRS, and RS represent tillering stage, panicle initiation stage, heading and flowering stage, milk-ripe stage, and ripening stage. “*” and “**” indicate that the significance test at the 0.05 and 0.01 levels passed, respectively. “n.s” indicates that the differences between treatments are not significant. (a) Leaf area index of rice in 2023; (b) leaf area index of rice in 2024; (c) dry matter accumulation in 2023; (d) dry matter accumulation in 2024.
Figure 10. Dynamic changes in the leaf area index and dry matter accumulation. TS, PIS, HFS, MRS, and RS represent tillering stage, panicle initiation stage, heading and flowering stage, milk-ripe stage, and ripening stage. “*” and “**” indicate that the significance test at the 0.05 and 0.01 levels passed, respectively. “n.s” indicates that the differences between treatments are not significant. (a) Leaf area index of rice in 2023; (b) leaf area index of rice in 2024; (c) dry matter accumulation in 2023; (d) dry matter accumulation in 2024.
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Figure 11. Paddy soil temperature during the growth period. (a) Soil temperature in 2023; (b) soil temperature in 2024.
Figure 11. Paddy soil temperature during the growth period. (a) Soil temperature in 2023; (b) soil temperature in 2024.
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Figure 12. The correlations between soil temperature and stem diameter and root volume. Subfigures (a,c) represent the correlations between soil temperature and stem diameter, and soil temperature and root volume under the 2023 CKCD treatment, respectively; subfigures (b,d) show the corresponding correlations for the 2023 CCD treatment; subfigures (e,g) illustrate the relationships between soil temperature and stem diameter, and soil temperature and root volume under the 2024 CKCD treatment, respectively; subfigures (f,h) demonstrate these correlations for the 2024 CCD treatment.
Figure 12. The correlations between soil temperature and stem diameter and root volume. Subfigures (a,c) represent the correlations between soil temperature and stem diameter, and soil temperature and root volume under the 2023 CKCD treatment, respectively; subfigures (b,d) show the corresponding correlations for the 2023 CCD treatment; subfigures (e,g) illustrate the relationships between soil temperature and stem diameter, and soil temperature and root volume under the 2024 CKCD treatment, respectively; subfigures (f,h) demonstrate these correlations for the 2024 CCD treatment.
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Figure 13. The correlations between the rice root volume and plant height and dry matter accumulation. Subfigures (a,c) represent the correlations between root volume and plant height, and root volume and dry matter accumulation under the 2023 CKCD treatment, respectively; subfigures (b,d) show the corresponding correlations for the 2023 CCD treatment; subfigures (e,g) illustrate the relationships between root volume and plant height, and root volume and dry matter accumulation under the 2024 CKCD treatment, respectively; subfigures (f,h) demonstrate these correlations for the 2024 CCD treatment.
Figure 13. The correlations between the rice root volume and plant height and dry matter accumulation. Subfigures (a,c) represent the correlations between root volume and plant height, and root volume and dry matter accumulation under the 2023 CKCD treatment, respectively; subfigures (b,d) show the corresponding correlations for the 2023 CCD treatment; subfigures (e,g) illustrate the relationships between root volume and plant height, and root volume and dry matter accumulation under the 2024 CKCD treatment, respectively; subfigures (f,h) demonstrate these correlations for the 2024 CCD treatment.
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Table 1. Fertilization plans and nutrient inputs.
Table 1. Fertilization plans and nutrient inputs.
Fertilization Date (MM/DD)Fertilization TypeFertilizers and Application AmountsNutrient Inputs/(kg ha−1)
NP2O5K2O
9 May 2023Base fertilizer(1) Green source organic fertilizer (N-P2O5-K2O = 2.84%-4.96%-2.02%), 1200 kg ha−1;
(2) Jiuyuan organic bio-fertilizer (N-P2O5-K2O = 3%-1%-1.7%), 1500 kg ha−1;		39.5474.5249.74
20 May 2023Base fertilizerGreen intelligent rice special fertilizer (compound fertilizer: N-P2O5-K2O = 15%-11%-14%), 525 kg/ha;78.7557.7573.5
31 May 2023Tillering fertilizerUrea (TN ≥ 46.5%), 225 kg ha−1;104.54//
20 July 2023Panicle fertilizerPotassium chloride (K2O ≥ 60%), 45 kg ha−1;//27
19 May 2024Base fertilizer(1) Green intelligent rice special fertilizer (compound fertilizer: N-P2O5-K2O = 15%-11%-14%), 600 kg ha−1;
(2) Yuyuanwo biological bacterial fertilizer (N-P2O5-K2O = 3.22%-3.67%-3.05%), 600 kg ha−1		109.3288102.3
9 June 2024Tillering fertilizerUrea (TN ≥ 46.5%), 225 kg ha−1;104.54//
25 July 2024Panicle fertilizerPotassium chloride (K2O ≥ 60%), 75 kg ha−1;//45
Table 2. Water regulation thresholds.
Table 2. Water regulation thresholds.
TreatmentDepth of Water Rice Growth Stages
Recovery StagePre-Tillering StageMid-Tillering StagePost-Tillering StagePanicle Initiation StageHeading and Flowering StageMilk-Ripe StageRipening Stage
CKCDUpper limit (mm)25505050505050Natural drying
Lower limit (mm)5100% θs100% θs100% θs100% θs100% θs100% θs
Storage depth (mm)251/3 H1/3 H501/4 H1/4 H1/4 H
CCDUpper limit (mm)25100% θs100% θs100% θs100% θs100% θs100% θs
Lower limit (mm)580% θs70% θs65% θs80% θs85% θs75% θs
Storage depth (mm)251/3 H1/3 H501/3 H1/3 H1/3 H
Storage duration/d 222333
Root observation depth (mm) 0–2000–2000–2000–3000–4000–400
Note: θs indicates the saturated moisture content of soil (volumetric water content); H stands for the rice plant height, cm.
Table 3. Rice yields and water productivity under different irrigation patterns.
Table 3. Rice yields and water productivity under different irrigation patterns.
YearTreatmentsIrrigation Amounts (mm)Yields (kg ha−1)Irrigation Productivity (kg m−3)
2023CKCD773.311,574.21.5
CCD562.212,322.72.2
2024CKCD889.611,121.21.3
CCD422.111,542.22.7
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Wang, Y.; Liu, Q.; Chen, L.; Lu, Q.; Li, S.; Hu, N.; Qiu, S.; Wang, S. Effects of Water-Saving and Controlled Drainage Water Management on Growth Indices of Mechanically Transplanted Rice Under Side Deep Fertilization Conditions. Agriculture 2025, 15, 803. https://doi.org/10.3390/agriculture15080803

AMA Style

Wang Y, Liu Q, Chen L, Lu Q, Li S, Hu N, Qiu S, Wang S. Effects of Water-Saving and Controlled Drainage Water Management on Growth Indices of Mechanically Transplanted Rice Under Side Deep Fertilization Conditions. Agriculture. 2025; 15(8):803. https://doi.org/10.3390/agriculture15080803

Chicago/Turabian Style

Wang, Ying, Qingsheng Liu, Lihong Chen, Qilin Lu, Shiwei Li, Neng Hu, Shitong Qiu, and Shufang Wang. 2025. "Effects of Water-Saving and Controlled Drainage Water Management on Growth Indices of Mechanically Transplanted Rice Under Side Deep Fertilization Conditions" Agriculture 15, no. 8: 803. https://doi.org/10.3390/agriculture15080803

APA Style

Wang, Y., Liu, Q., Chen, L., Lu, Q., Li, S., Hu, N., Qiu, S., & Wang, S. (2025). Effects of Water-Saving and Controlled Drainage Water Management on Growth Indices of Mechanically Transplanted Rice Under Side Deep Fertilization Conditions. Agriculture, 15(8), 803. https://doi.org/10.3390/agriculture15080803

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