Search Results (177)

Astragalus sinicus, a key leguminous green manure widely cultivated in Southern China’s rice-based cropping systems, plays a pivotal role in sustainable agriculture by enhancing soil organic matter sequestration, improving rice yield, and elevating grain quality. The symbiotic nitrogen-fixing association between A. sinicus and its matching rhizobia is fundamental to its agronomic value; however, suboptimal inoculant efficiency and field application methodologies constrain its full potential. To address these limitations, we conducted a multi-phase study involving (1) rhizobial strain screening under controlled greenhouse conditions, (2) an optimized lyophilization protocol evaluating cryoprotectant (trehalose, skimmed milk powder and others), and (3) seed pelleting trails with rhizobial viability and nodulation assessments over different storage periods. Our results demonstrate that Mesorhizobium huakuii CCBAU 33470 exhibits a superior nitrogen-fixing efficacy, significantly enhancing key traits in A. sinicus, including leaf chlorophyll content, tiller number, and aboveground biomass. Lyophilized inoculants prepared with cryoprotectants (20% trehalose or 20% skimmed milk powder) maintained >90% bacterial viability for 60 days and markedly improved nodulation capacity relative to unprotected formulations. The optimized seed pellets sustained high rhizobial loads (5.5 × 10³ cells/seed) with an undiminished viability after 15 days of storage and nodulation ability after 40 days of storage. This integrated approach of rhizobial selection, inoculant formulation, and seed coating overcomes cultivation bottlenecks, boosting symbiotic nitrogen fixation for A. sinicus cultivation. Full article

Mushroom production is a sustainable practice but requires improvements, such as in Lentinula edodes (Berk) Pegler cultivation, which has high water and labor demands. In this context, this study proposed replacing the traditional primordia induction method by submersion with a water injection method. Two primordia induction methods (submersion and injection) and two cultivation block formats were compared: rectangular cube (2 kg) and cylindrical (3.5 kg). The substrate, composed of eucalyptus sawdust (72%), wheat bran (12.5%), rice bran (12.5%), CaCO₃ (1%), and CaSO₄ (2%), was inoculated with strain LED 19/11 and incubated for 80 days at 26 ± 5 °C and 85 ± 15% humidity. After this period, the blocks were washed and transferred to the production environment. Fruiting was induced either by submersion or water injection, and production was evaluated over four harvest flushes. The 2 kg blocks had higher yields with submersion (16.62%), while the 3.5 kg blocks responded better to injection (13.01%), showing more homogeneous production. Increasing the substrate quantity contributes to greater harvest stability across production cycles. Water injections proved to be a viable alternative, reducing handling and facilitating large-scale production. The use of this technique demonstrates great importance in reducing water use and also the need for labor in cultivation. Full article

This study presents an integrated spatiotemporal assessment of drought conditions in the Thung Kula Ronghai region of Northeastern Thailand from 2001 to 2023. Multiple satellite-derived drought indices, including SPI, SPEI, RDI, and AI, together with NDVI anomalies, were used to detect seasonal and long-term drought dynamics affecting rainfed Hom Mali rice production. The results show that dry season droughts now affect up to 17 percent of the region’s agricultural land in some years, while severe drought zones persist across more than 2.5 million hectares over the 20-year period. In the most recent 5 years, approximately 50 percent of cultivated areas experienced moderate to severe drought conditions. The RDI showed the strongest correlation with NDVI anomalies (r = 0.22), indicating its relative value for assessing vegetation response to moisture deficits. The combined index approach delineated high-risk sub-regions, particularly in central Thung Kula Ronghai and lower Surin, where drought frequency and severity have intensified. These findings underscore the region’s increasing exposure to dry-season water stress and highlight the need for site-specific irrigation development and adaptive cropping strategies. The methodological framework demonstrated here provides a practical basis for improving drought monitoring and early warning systems to support the resilience of Thailand’s high-value rice production under changing climate conditions. Full article

The high water demand of rice cultivation is mainly due to flood irrigation, which requires large volumes not only to meet evapotranspiration needs, but also due to losses from percolation, lateral seepage, and surface runoff. In addition to lowering water use efficiency, surface runoff may transport nutrients. This study aimed to calibrate and validate a daily water balance model to estimate surface runoff losses across three rice-growing seasons. During the first two seasons, different model components were calibrated by comparing simulated and observed water depths. In the final season, the calibrated model was validated using direct runoff measurements obtained from weirs and flowmeters. Results showed strong agreement between model estimates and direct measurements of water depth and surface runoff. Linear regression models showed good fit, with coefficients of determination (R²) above 0.80 for water depth and 0.79 for runoff. A validated daily water balance model, combined with periodic monitoring of water depth, proved to be a reliable tool for estimating surface runoff during the rice-growing season. Total runoff—from irrigation, rainfall, and final drainage—represented between 7.5% and 18% of the total water input. This approach offers a practical tool for improving irrigation water management and understanding runoff-driven nutrient transport. Full article

Biodegradable mulch films not only provide similar field benefits to conventional mulch films but also degrade naturally, rendering them an effective alternative to traditional polyethylene mulch films for mitigating “white pollution”. However, recent studies have focused on the material selection and soil ecological impacts of biodegradable mulch films, while their effects on soil water temperature regulation and root architecture in drip-irrigated rice cultivation remain unclear. To address this research gap, in this study, various treatments including no mulch (NM), conventional plastic mulch (PM), and four types of biodegradable mulch films (BM-W₁, BM-B₁, BM-B₂, and BM-B₃) were established, and their effects on the soil hydrothermal flux, root architecture, biomass accumulation, and resource use efficiency of drip-irrigated rice were analyzed at different growth stages. The results indicated the following: (1) Compared with the NM treatment, film mulching increased the soil hydrothermal fluxes and water retention capacity, thereby promoting root growth and biomass accumulation, ultimately increasing the effective panicle number and grain yield. (2) Among the biodegradable film treatments, BM-B₃ (with a degradation period of 105 days) maintained relatively higher soil temperature for a longer duration, which increased surface root distribution in the mid-to-late growth stages, further improving fine root growth and biomass accumulation, consequently enhancing both yield and water use efficiency. In contrast, BM-B₁ and BM-B₂ exhibited excessively rapid degradation rates, leading to significant fluctuations in soil moisture and temperature, thereby negatively affecting water supply and nutrient uptake and ultimately restricting root growth and development. (3) The entropy weight (EW) technique for order of preference by similarity to ideal solution (TOPSIS) model results revealed that although the PM treatment was more advantageous in terms of soil temperature, root dry weight, and soil moisture content, BM-B₃ provided a slightly higher yield than the PM treatment did and offered the advantage of biodegradability, making it a preferred alternative to conventional mulch film. In summary, this study revealed the mechanism by which biodegradable mulch films enhanced biomass accumulation and yield formation in drip-irrigated rice production by optimizing soil hydrothermal dynamics and root architecture, thereby exploring their potential as replacements for conventional mulch films. These findings provide a theoretical basis for the efficient and sustainable production of drip-irrigated rice in arid regions. Full article

The contamination of paddy soils with arsenic (As) and cadmium (Cd), coupled with the depletion of soil organic carbon (SOC), poses significant threats to rice yields and quality. There is an urgent need to identify a suitable soil additive capable of achieving simultaneous heavy metal remediation and promotion of organic matter enrichment. The current study introduced two novel iron (Fe)/magnesium (Mg)-based bimetal-oxide-modified rice straw biochar (RSB), namely RSB-Fe/Mn and RSB-Fe/Mg. It evaluated their effectiveness in As/Cd immobilization and SOC preservation. An 8-week cultivation experiment was carried out in sequential drying–flooding moisture fluctuation conditions, with the soil pore water As/Cd (PWAs/Cd) and SOC fractions monitored. The mechanisms of As/Cd immobilization were investigated using Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), and X-ray Photoelectron Spectroscopy (XPS) characterizations. Results revealed that PWAs and PWCd were reduced by up to 67.1% and 80.2% during the drying period and by 27.0% and 76.5% during the flooding period, respectively. Additionally, SOC content increased by 16.3% and 33.9% with RSB-Fe/Mn addition during the drying and flooding period, respectively, with an increase in the mineral-associated organic carbon (MAOC) fraction. The study proves that RSB-Fe/Mn and RSB-Fe/Mg are effective for soil As/Cd passivation and SOC stabilization, offering a promising solution to mitigate As and Cd pollution in paddy soils while maintaining soil quality. Full article

Flooding in Tempe Lake, Indonesia, poses ongoing socioeconomic challenges, mainly affecting food security, agricultural output, and household livelihoods. The recurrent and unpredictable floods disrupt planting and harvesting periods, resulting in significant food production deficits and posing complex adaptive challenges for residents. This study examines the socioeconomic adaptation strategies employed by rice farmer households to mitigate the adverse effects of flooding. The study analyzed a random sample of 160 people, utilized descriptive–analytical methodologies, and displayed the findings through graphs and matrix tables. Research reveals that fishing and rice farming serve as the primary revenue sources for households in the region. Despite financial challenges, households maintain security due to dependable food sources and proximity to the lake. The study emphasises the importance of efficient rice cultivation management owing to its short growth cycles and vulnerability to flooding. Moreover, freshwater aquaculture presents a sustainable strategy for mitigating flood risks in climate change, mainly when supported by microcredit, training, and improved market access. The findings highlight the necessity of social and structural adjustments in reducing vulnerability and enhancing community resilience, offering substantial recommendations for improving long-term resilience and food security in flood-prone regions. Full article

Accurate mapping of rice planting areas is of great significance in terms of food security and market stability. However, the existing research into high-resolution rice mapping has relied heavily on fine-scale temporal remote sensing image data. Due to cloud occlusion and banding problems, data extraction from Landsat series remote sensing images with medium spatial resolution is not optimal. Therefore, this study proposes a rice mapping method (LR) using Google Earth Engine (GEE), which uses Landsat images and integrates automatic generation of training samples and a machine learning algorithm, with the assistance of phenological methods. The proposed LR method initially generated rice distribution maps based on phenology, and 300 sample points were selected for meta-identification of rice images via an enhanced pixel-based phenological feature composite method (Eppf-CM) utilizing high-resolution imagery. Subsequently, the inundation frequency (F) and an improved sample point statistical feature, i.e., the ratio of change amplitude of LSWI to NDVI (RCLN), were introduced to combine Eppf-CM with combined consideration of vegetation phenology and surface water variation (CCVS) methods, to automate the generation of training data with the aid of phenology. The sample data were optimized by an alternate iterative method involving extraction of neighborhood information. Finally, a random forest (RF) probabilistic model trained by integrating data from different phenological periods was used for rice mapping. To test its performance, we mapped rice distribution at 30 m resolution (“LR_Rice”) across Heilongjiang Province, China from 2010 to 2022, with annual overall accuracy (OA) and Kappa coefficients greater than 0.97 and 0.95, respectively, and compared them with four existing rice mapping products. The spatial distribution characteristics of rice cultivation extracted by the LR algorithm were accurate and the performance was optimal. In addition, the extracted area of LR_Rice was highly consistent with the agricultural statistical area; the coefficient of determination R² was 0.9915, and the RMSE was 22.5 kha. The results show that this method can accurately obtain large-scale rice planting information, which is of great significance for food security, water resource management, and environmentally sustainable development. Full article

The “enzyme latch” and “Fe gate” mechanisms are crucial factors influencing soil carbon sequestration capacity, playing a key role in understanding the dynamic changes in soil organic carbon (SOC). However, there is a lack of research regarding polyphenol oxidase (PPO) activity and the concentration of iron oxides in paddy soils under varying incubating temperatures and cultivation practices. This study was conducted over three years in a double-cropping rice area in southern China, incorporating systematic soil sampling to measure PPO activity, Fe oxide concentration, and basic physicochemical properties. The results showed that temperature did not significantly affect either PPO activity or the concentration of Fe oxides. Additionally, compared to conventional management (CK), organic management led to a decrease in Fe oxides (Fe bound to organic matter, reactive Fe, and total free Fe) by 19.1%, 16.2%, and 13.7%, respectively (p < 0.05). At the same time, PPO activity did not show any significant changes. Our results indicated that short-term (5 weeks) incubation temperature did not affect PPO activity or Fe oxides, while organic farming decreased Fe oxides without influencing PPO activity. PPO activity increased with the length of the incubation period. Full article

The cultivation of Chinese milk vetch (CMV) during the winter fallow season and the return of rice straw are important practices for increasing the soil fertility of paddy fields in southern China. In order to provide data-based evidence for the scientific strategy of nitrogen (N) fertilizer reduction through the incorporation of rice straw and CMV, a three-year field trial was conducted. The treatments included the three N application rates of 0%, 60%, and 100% of the local conventional rate (165 kg ha⁻¹), with the incorporation of CMV alone (MN0, MN60, and MN100) or with both CMV and rice straw (SMN60 and SMN100). The rice grain yield, N uptake, and dynamic changes in inorganic N in the soil and surface water were determined for the period from 2019 to 2021. The results show that both the rice grain yield and plant N uptake of the MN60 and SMN60 treatments were not significantly different from those of the treatment with only conventional N application (N100). Although the SMN100 treatment significantly increased the uptakes of N in the aboveground part in the tillering and shooting stages compared with SMN60, no significant differences were found between the grain yields in 2021. Meanwhile, the SMN60 treatment significantly increased the soil microbial biomass N and NH₄⁺-N contents during the maturity stage in 2020 and 2021, respectively, compared with MN60. Furthermore, the SMN100 treatment resulted in higher NO₃⁻-N concentrations in the surface water at days 3 and 6 after transplantation in 2020 than those under SMN60. In conclusion, the incorporation of CMV and rice straw with an application rate of 60% of conventional N fertilizer is an essential approach to reducing the risk of N loss while maintaining rice grain yields in the Jianghan Plain of China. Full article

In recent years, there has been widespread cultivation of high-quality rice along the southeast coast of China, particularly in Shanghai. However, the specific changes in the yield and quality performance of rice in the Shanghai region have not been well understood. A study conducted on 194 rice varieties in the Shanghai region from 1994 to 2023 focused on yield, growth characteristics, and quality. The findings revealed significant increases in rice yield (+16.8%) and spikelets per panicle (+45.4%) in the Shanghai region over the past 30 years, along with a decrease in amylose content (−27.9%). However, parameters such as grain filling, 1000-grain weight, plant height, panicle length, chalkiness, and gel consistency showed no significant changes over the same period. Additionally, the study found that the yield, nitrogen application amount, growth period, and head rice rate of japonica rice and indica-japonica hybrid rice were higher than those of indica rice, although the panicle length was lower in comparison. Japonica inbred rice exhibited the lowest amylose content and superior taste. Correlation analyses suggested that the breeding of japonica rice varieties in the Shanghai region should focus on balancing nitrogen absorption and high chalkiness, plant biomass, and amylose content, and yield and the appearance and taste quality of rice. In addition, the potential rice yield per unit area in the Shanghai region in the future depends on the promotion of hybrid japonica rice planting and developing best management practices. Full article

In response to increasing global food demand and the significant water requirements of rice cultivation, this study aims to enhance water use efficiency in rice farming. Focusing on Jiayu County, a subtropical humid region in China, where rice is grown as a single crop every year, we investigated temporal variations in rice water requirements and the influence of effective rainfall on irrigation strategies. Data were collected from an experimental station within the Sanhulianjiang Reservoir in Jiayu County. Utilizing the Mann–Kendall trend test and the Seasonal–Trend Decomposition using the LOESS (STL) method, we analyzed historical data on rice water requirement (ET_c) and effective rainfall ($R_e$ ). Our findings reveal that annual water requirements for rice range between 432 mm and 746 mm, with peaks corresponding to critical growth stages such as tillering and jointing–booting. Effective rainfall contributes significantly to meeting these needs, providing 27–35% of the total water requirement during specific periods. Developed water-saving irrigation strategies, including optimized irrigation scheduling and the introduction of drought-resistant rice varieties, demonstrate a potential reduction in irrigation demands by approximately 33.84%. This study underscores the importance of integrating effective rainfall data into irrigation practices to enhance water use efficiency and promote sustainable rice production amidst climate variability challenges. Full article

Previous studies have shown that a one-time application of polymer-coated urea (PCU) can increase rice yield and nitrogen (N) uptake. However, the connection between rice root morphology and physiological traits and grain yield and N absorption has still not been well understood. The objective of this study was to explore whether one-time application of PCU could enhance shoot growth, improve plant physiological activity, and ultimately boost rice yield and NUE by optimizing root morphological and physiological traits. In this study, a super-large-panicle indica-japonica hybrid rice variety, Yongyou1540, was cultivated under three N treatments during 2022 and 2023: (1) 0N, throughout the entire growth period, no N fertilizer was applied; (2) LFP, local farmers’ N management practices were followed, using urea as the N source, and N fertilizer management was carried out according to the local farmers’ customary fertilization practices; and (3) PCU, a one-time application of PCU was performed at one day before transplanting. PCU is a controlled-release fertilizer in which urea granules are coated with a synthetic polymer layer; it has been widely used in rice cultivation. In both LFP and PCU treatments, N was applied at a rate of 200 kg N ha⁻¹. PCU is a type of controlled-release fertilizer in which urea granules are coated with a layer of synthetic polymer. Compared to LFP, PCU significantly improved several root morphological traits, including increased deep-root proportion and specific root length (SRL), throughout the entire growth period; increased root length and root length density at heading and maturity; and increased root biomass growth rate from jointing to heading and reduced reduction rate after heading. Additionally, PCU enhanced root oxidative activity (ROA) and increased zeatin and zeatin riboside (Z+ZR) content in both roots and root bleeding sap at the middle and late grain-filling stages. Furthermore, PCU markedly increased the flag-leaf net photosynthetic rate, Z+ZR content in leaves, and activities of key enzymes involved in sucrose-to-starch conversion in grains during the middle and late grain-filling stages. Correlation analysis indicated that root and shoot biomass growth rate showed a significant positive correlation before heading, and that root biomass reduction rate was significantly negatively correlated with shoot biomass growth rate after heading. ROA and Z+ZR content in both roots and root bleeding sap were significantly associated with flag-leaf photosynthetic rate, Z+ZR content in leaves, and the activities of key enzymes involved in the sucrose-to-starch conversion in grains. On average, PCU increased rice yield by 10.0% and agronomic NUE by 46.2%, compared to LFP. These findings suggest that PCU could optimize root morphological and physiological traits, and thereby promote shoot growth, enhance physiological activity, and ultimately increase both rice yield and NUE. Further research could also investigate the potential for combining PCU with other agronomic practices to enhance both rice yield and NUE. Full article

Rice is one of the most extensively cultivated food crops in Northeast China. Estimating pre-harvest rice yield is important for accurately formulating field management strategies and swiftly assessing overall rice production. This can be achieved using a pixel-scale model, which estimates crop yield based on information from each pixel. Previous studies predominantly employed remote sensing indices, climatic data, and yield statistics of rice across either single or all growth periods for yield estimation. These approaches are limited by a delay in yield estimation and are insufficient in the exploration of time-series feature variables at the pixel scale. This study presents the development of a novel deep-learning framework designed for the early estimation of rice yield in Qian Gorlos County, Northeast China. The framework utilizes a long short-term memory neural network integrated with an attention mechanism (ALSTM). In this framework, the heading stage–milk ripening stage is the time window for early yield estimation, and the vegetation indices Normalized Difference Red Edge (NDRE), Green Chlorophyll Vegetation Index (GCVI), and Normalized Difference Water Index (NDWI) from the rice transplanting to the milk ripening stage are time-series feature variables. The yield estimation precision is R² = 0.88, RMSE = 341.82 kg/ha, MAE = 280.29 kg/ha, outperforming LASSO (R² = 0.71, RMSE = 567.10 kg/ha, MAE = 487.38 kg/ha), RF (R² = 0.79, RMSE = 506.70 kg/ha, MAE = 418.90 kg/ha), and LSTM (R² = 0.83, RMSE = 451.11 kg/ha, MAE = 326.31 kg/ha). The ALSTM introduced in this paper demonstrates its robustness after being generalized to the 2022 growing season. It can forecast the current-year rice yield two months prior to harvest, providing a valuable reference for developing field management strategies to enhance rice productivity. Full article

Due to the limited availability of high-quality optical images during the rice growth period in the Lingnan region of China, effectively monitoring the rice planting situation has been a challenge. In this study, we utilized multi-temporal Sentinel-1 data to develop a method for rapidly extracting the range of rice fields using a threshold segmentation approach and employed a U-Net deep learning model to delineate the distribution of rice fields. Spatio-temporal changes in rice distribution in Leizhou City, Guangdong Province, China, from 2017 to 2021 were analyzed. The results revealed that by analyzing SAR-intensive time series data, we were able to determine the backscattering coefficient of typical crops in Leizhou and use the threshold segmentation method to identify rice labels in SAR-intensive time series images. Furthermore, we extracted the distribution range of early and late rice in Leizhou City from 2017 to 2021 using a U-Net model with a minimum relative error accuracy of 3.56%. Our analysis indicated an increasing trend in both overall rice planting area and early rice planting area, accounting for 44.74% of early rice and over 50% of late rice planting area in 2021. Double-cropping rice cultivation was predominantly concentrated in the Nandu River basin, while single-cropping areas were primarily distributed along rivers and irrigation facilities. Examination of the traditional double-cropping areas in Fucheng Town from 2017 to 2021 demonstrated that over 86.94% had at least one instance of double cropping while more than 74% had at least four instances, which suggested that there is high continuity and stability within the pattern of rice cultivation practices observed throughout Leizhou City. Full article