Search Results (14)

Weak seedlings and poor growth uniformity affect the mechanical transplanting of densely sown rice seedlings. To address these issues, seedlings of the conventional japonica rice “Zhehexiang 2” were grown in a traditional flat tray (control), pot-mat tray (26 × 52 bowls; BT(26)), and pot-mat tray (30 × 58 bowls; BT(30)) to compare the effects of different specifications of pot-mat trays (BTs) on the growth and quality of mechanical transplanting of densely sown rice seedlings with 250 g/tray. The BT-raised seedlings showed improved seedling quality, with increases in the shoot and root dry weights by 7.44% and 20.11%, respectively, compared to the flat tray. Under the dense sowing rate, the plant height uniformity of the BT(26) and BT(30) treatments was significantly increased by 6.95% and 3.43%, and the root entwining force of the seedlings was 14.28% and 10.21% higher, respectively, compared with those of the control. The missing hill rate for BT-raised seedlings after mechanical transplanting was significantly reduced by 53.15%. The loss of roots during mechanical transplanting was reduced. Compared with the control, the root length, root surface area, and root number were increased, and a greater number of large roots were retained, which promoted the early development of seedlings after mechanical transplanting. The proportion of holes with two to five seedlings was higher after mechanical transplanting. The pot-mat tray divided the root growth area of seedlings, promoted the growth of the seedlings, and reduced the root loss and missing hill rate under the high sowing rate. Thus, the quality of mechanical transplanting of densely sown seedlings was improved. Full article

Vertical farming is gaining popularity as a sustainable solution to global food demand, particularly in urban areas where space is limited. However, optimizing key factors such as planting density remains a critical issue, as it directly affects light interception, energy efficiency, and crop yield. Lettuce and basil, the most commonly grown crops in vertical farms, were chosen for this study, with the aim of addressing the impact of planting density on light interception and overall productivity for improving the performance and sustainability of vertical farming systems. Plants were grown in an ebb-and-flow system of a fully controlled experimental vertical farm, where light was provided by light-emitting diode fixtures delivering a photoperiod of 16 h d⁻¹ and 200 µmol m⁻² s⁻¹ of photosynthetic photon flux density. Experimental treatments included three planting densities, namely 123 (low density, LD), 237 (medium density, MD), and 680 (high density, HD) plant m⁻². At the final harvest (29 days after sowing), the adoption of the highest planting density (680 plant m⁻²) resulted in greater fresh yield (kg FW m⁻²), leaf area index (LAI, m² m⁻²), light use efficiency (LUE, g DW mol⁻¹) and light energy use efficiency (L-EUE, g FW kWh⁻¹) for both lettuce (+207%, +227%, +142%, +206%, respectively), and basil (+312%, +316%, +291, +309%, respectively), as compared to the lowest density (123 plant m⁻²). However, the fresh and dry weights of the individual plants were lowered, probably as a result of the reduced light availability due to the highly dense plants’ canopy. Overall, these findings underscore the potential of increasing planting density in vertical farms to enhance yield and resource efficiency. Full article

To address the problems of the inaccurate seeding rate and uneven seeding in the process of dense planting of winter wheat in Xinjiang, according to the physical characteristics of the wheat seeds and the agronomic requirements of the high-yield cultivation techniques for the winter wheat “well” type, a double-hole wheel-type densely planted wheat hole sower was designed and produced. Through theoretical design and research, the structural design of the overall hole seeder and its key components was completed. The findings indicated that 5–7 wheat seeds could be planted in each hole at a 9.2 mm nest depth and 610 mm³ nest volume, which was consistent with the “well”-type high-yield dense-planting cultivation technology’s need for 400,000–500,000 basic seedlings per mu. The rotation speed and the quantity of the wave guide teeth were used as test factors and the qualifying index, replay index, and missed sowing index were used as test indicators to create the two-factor, three-level central composite design center combination test. It was possible to derive the mathematical model connecting the test factors and test indexes. The regression model underwent multi-objective optimization using the Design-Expert 13 program to determine the optimal parameters: the qualifying index was 91.24%, the replay index was 6.14%, and the missed seeding index was 2.62% when the wave guide rail had four teeth and the seed drill rotated at a speed of 40 revolutions per minute. The best parameter combinations were used for a bench verification test, and the test indicated that the qualified index was 90.25%, the replay index was 4.59%, and the missed broadcast index was 5.16%. The results demonstrated that the densely planted wheat hole seeder performs well, satisfies the requirements for winter wheat dense-planting and sowing operations, and serves as a model for the densely planted wheat hole seeders that will be optimized in the future. Full article

The key problem in the cultivation of densely planted dwarf orchards is the removal of weeds—trees’ competitors for habitat resources. There is an urgent need to look for ecological methods of weed control as an alternative to herbicides that are harmful to the environment. The use of living mulch (LM) in tree rows additionally improves soil quality but usually weakens tree growth and may reduce yield. The aim of this 11-year experiment was to assess the impact of the use of two different LMs in rows (Trifolium repens—Tr and Agrostis capillaris—Ac) on the growth, yield, and fruit quality of three pear cultivars on Quince S₁ rootstock compared to herbicide fallow. The presence of LM did not significantly affect tree growth. There was no significant effect of either mulch on the cumulative yield. However, for the first 4–6 years, the yield was clearly lower than in the control, which changed in the later years of the experiment. When LMs were used, pear trees showed a significantly lower tendency to alternate fruiting. The average fruit weight was significantly lower in Tr, but the other parameters of external fruit quality did not differ significantly. Furthermore, a smaller share of ultra-small fruit was found with LM compared to the control. The LM did not significantly affect such parameters as the content of soluble solids, vitamin C, Ca, Mg, and P. The use of Ac in dwarf pear orchards with sowing in tree rows is recommended in the 2nd or 3rd year after planting at the earliest. Full article

Fine dust can have serious effects on human health and crop growth. Fodder crops can reduce airborne dust by coagulating soil particles and reducing wind speed on the surface and have the effect of reducing fine dust by adsorbing it on the crop surface. In this study, the dust reduction coefficient of crops was derived through a self-manufactured wind tunnel experiment to quantitatively assess the dust reduction effect of crops by type and planting density. Additionally, a dust reduction formula considering crop growth and weather conditions during the cultivation period was derived. The dust reduction coefficient was measured by the gravimetric method and the real-time size distribution of dust concentration before and after the crop. The PM reduction coefficient showed triticale at PM-2.5 82.2 mg/m³, PM-10 120 mg/m³, and barley at PM-2.5 14.5 mg/m³, PM-10 26.9 mg/m³ under moderate planting density. During the general planting density cultivation period of triticale and barley, PM-10 was reduced by 37.8 kg/ha and 8.5 kg/ha, respectively, and PM-2.5 was reduced by 25.9 kg/ha and 4.6 kg/ha. The dust reduction effect during the cultivation period was up to 126.1 kg/ha in terms of PM-10 when triticale was cultivated with densely sowing planting density. Full article

In maize (Zea mays L.), rational root structure promotes high grain yield under dense sowing conditions. This study was conducted at Qitai Farm in Xinjiang, China, in 2019 and 2021. A traditional wide and narrow row planting method was adopted, with wide rows of 0.7 m and narrow rows of 0.4 m. The cultivars DH618 and SC704, which have grain yield potentials of 22.5 and 15 Mg ha⁻¹, respectively, were selected for study of the root structure and distribution characteristics under high-yield and high-density planting conditions. The highest yield (20.24 Mg ha⁻¹) was achieved by DH618 under a planting density of 12 × 10⁴ plants ha⁻¹. The root structure of DH618 was well developed at that planting density, and the root dry weight (RDW) was 17.49 g plant⁻¹ and 14.65 g plant⁻¹ at the silking and maturity stages, respectively; these values were 7.56% and 11.86% higher, respectively, than those of SC704. At the silking stage, the proportions of RDW at soil depths of 0–10, 10–20, 20–40, and 40–60 cm were 66.29%, 11.83%, 16.51%, and 5.38%, respectively, for DH618; over the 20–60 cm soil layer, this was an average of 4.04% higher than the RDW of SC704. At maturity, the proportions of RDW at soil depths of 0–10, 10–20, 20–40, and 40–60 cm were 61.40%, 11.19%, 17.19%, and 10.21%, respectively, for DH618, which was an average of 9.59% higher than that of SC704 over the 20–60 cm soil layer. At maturity, DH618 roots were mainly distributed in the narrow rows, accounting for 72.03% of the root structure; this was 9.53% higher than the roots of SC704. At silking and maturity, the root weight densities of DH618 were 471.98 g m⁻³ and 382.98 g m⁻³, respectively (5.18% and 5.97% higher, respectively, than the root weight densities of SC704). The root lengths of DH618 were 239.72 m plant⁻¹ and 199.04 m plant⁻¹ at the silking and maturity stages, respectively; these were 16.45% and 25.39% higher, respectively, than the root lengths of SC704. The root length densities were 0.58 cm cm⁻³ and 0.46 cm cm⁻³ at the silking and maturity stages, respectively, and these were 16.86% and 17.08% higher, respectively, than the root length densities of SC704. This study indicated that the maize hybrid DH618 had a more developed root structure with increased root distribution in the deep soil and narrow rows under high-density planting compared to cultivar SC704, contributing to high grain yield under dense planting. Full article

Currently, an agricultural method called Synecoculture^TM has been receiving attention as a means for multiple crop production and recovering from environmental degradation; it helps in regreening the environment and establishing an augmented ecosystem with high biodiversity. In this method, several types of plants are grown densely, and their management relies mainly on manual labor, since conventional agricultural machines and robots cannot be applied in complex vegetation. To improve work efficiency and boost regreening by scaling-up Synecoculture, we developed a robot that can sow, prune, and harvest in dense and diverse vegetation that grows under solar panels, towards the achievement of compatibility between food and energy production on a large scale. We adopted a four-wheel mechanism with sufficient ability to move on uneven terrain, and a two orthogonal axes mechanism with adjusted tool positioning while performing management tasks. In the field experiment, the robot could move straight on shelving slopes and overcome obstacles, such as small steps and weeds, and succeeded in harvesting and weeding with human operation, using the tool maneuver mechanism based on the recognition of the field situation through camera image. Full article

The belt uniform (BU) sowing pattern can improve the yield of winter wheat, but whether and how the BU sowing pattern can increase yield under different sowing densities is unknown. The field study was conducted in Guiyang (Guizhou province) during the growing season in 2017–2018, 2018–2019, and 2019–2020. Four winter wheat cultivars were used in field experiments to investigate the changes of the dry matter accumulation and partition, yield and yield components at maturity under five sowing densities (75, 150, 225, 300, and 375 plants per m²), and three sowing patterns: line and dense (LD) sowing with 33.3 cm row spacing (LDS); the belt uniform (BU) sowing with 15 cm (BUN), and 20 cm (BUW) row spacing. The BU sowing pattern significantly increases shoot dry matter and grain yield in all four winter wheat cultivars under all five sowing densities and in each growing season, particularly under the high sowing density of 300 and 375 plants m⁻². Harvest index was unaffected by the different sowing densities and sowing patterns. While spike number increased, grain weight per spike decreased with the increase in sowing density. The 1000-grain weight and grain number per spike were unaffected by the sowing patterns. The variation in the shoot dry weight can explain 94% variation in grain yield and 66% variation in spike number. Allometric analysis showed that more dry matter was partitioned to the spike than to the stem and leaf. We conclude that the BU sowing pattern can increase grain yield under high sowing densities associated with a high shoot dry matter accumulation and its partition to the spike. Full article

Relay intercropping is considered a valuable agroecological practice to increase and stabilize crop yields while ensuring the provision of several ecosystem services as well as sustainability and resilience to changing climatic conditions. However, farmers are still reluctant in the use of intercropping practices since there is a huge knowledge gap regarding the time of sowing, sowing ratio, crop stand density, and cultivar choice. In this study, we carried out a 3-year field experiment in Central Italy to assess the effect of relay intercropping on the agronomic performance and competitiveness of winter durum wheat (Triticum durum Desf. cv. Minosse) and spring lentil (Lens culinaris Medik. cv. Elsa) under a low-input management system, comparing different crop stand types (monocrop vs. intercrop) and target plant densities (350 plants m²—full dose vs. 116 plants m²—1/3 dose). The results revealed that intercropping increased grain yield compared to monocropping: significantly (p < 0.0001) against both monocrops in 2021 and non-significantly against durum wheat in 2019 and 2020. Yield advantage in both intercropping systems ranged between 164 and 648%. Durum wheat competitiveness was stronger in 2019 and 2021, while lentil was the most competitive component in 2020. Intercropping favored P accumulation in durum wheat shoots. There was no difference in grain yield of both crops between the highly- and lowly-dense system in 2020 and 2021. Both intercropping strategies were as effective as mechanical hoeing in controlling weeds and proved beneficial in stabilizing lentil productivity. Further economic analysis capturing the additional costs incurred in intercropping and mechanical weeding would highlight the magnitude of profitability of these systems. Full article

In order to explore the optimal cultivar × sowing date × plant density for summer maize (Zea mays L.) in the Northern Huang–Huai–Hai (HHH) Plain of China, field experiments were conducted over two consecutive years (2018–2019) on a loam soil in the Northern HHH Plain. A split–split plot design was employed in this study, and the main plots included three cultivars (HM1: early-maturing cultivar; ZD958: medium-maturing cultivar; DH605: late-maturing cultivar); subplots consisted of three sowing dates (SD1: June 10; SD2: June 17; SD3: June 24); sub-sub plots include two plant densities (PD1: 6.75 × 10⁴ plants ha⁻¹; PD2: 8.25 × 10⁴ plants ha⁻¹). The results showed that the effects of cultivar and plant density on grain yield of summer maize were not significant, and the sowing date was the major factor affecting the grain yield. Delayed sowing significantly decreased the grain yield of summer maize, this was due mainly to the reduced kernel weight, which is associated with the lower post-anthesis dry matter accumulation. Moreover, radiation use efficiency (RUE), temperature use efficiency (TUE), and water use efficiency (WUE) were significantly affected by cultivar, sowing date, and plant density. Selecting early- and medium-maturing cultivars was beneficial to the improvements in RUE and TUE, and plants grown at earlier sowing with higher plant density increased the RUE and TUE. The interactive analysis of cultivar × sowing date × plant density showed that the optimum grain yields of all tested cultivars were observed at SD1-PD2, and the optimum RUE and TUE for HM1, ZD958, and DH605 were observed at SD1-PD2, SD2-PD2, and SD2-PD2, respectively. The differences in the optimum grain yield, RUE, and TUE among the tested cultivars were not significant. These results suggested that plants grown at earlier sowing with reasonable dense planting had benefits of grain yield and resource use efficiency. In order to adapt to mechanized grain harvesting, early-maturing cultivar with lower grain moisture at harvest would be the better choice. Therefore, adopting early-maturing cultivars grown with earlier sowing with reasonably higher plant density would be the optimal planting pattern for summer maize production in the Northern HHH Plain of China in future. Full article

Anthropogenic activity has caused persistent and prominent losses of forest cover in dry tropical forests. Natural regeneration of forest trees in grazed areas often fails due to lack of seed sources and consumption by ungulates. To address this, the effective restoration of such sites often requires fencing and outplanting nursery-grown seedlings. In the degraded, dry forests of tropical Hawaii, USA, an additional challenge to restoration of native forest trees is the introduced kikuyu grass (Cenchrus clandestinus). This invasive, rapidly growing rhizomatous plant forms deep, dense mats. We studied the use of nursery cultural techniques to facilitate the establishment of koa (Acacia koa) seedlings outplanted amidst well-established kikuyu grass on a volcanic cinder cone on the dry, western side of Hawaii Island. Seedlings were grown four months in three container sizes (49, 164, 656 cm³) and with four rates (0, 4.8, 7.2, and 9.6 kg m⁻³) of 15–9–12 (NPK) controlled-release fertilizer incorporated into media prior to sowing. After 16 months in the field, seedling survival was > 80% for all treatments with two exceptions: the non-fertilized 49 cm³ (78%) and 164 cm³ (24%) containers. After 10 years, only these two treatments had significantly lower survival (35% and 10%, respectively) than the other treatments. One year following planting, none of the non-fertilized seedlings had transitioned to phyllodes from juvenile true leaves, regardless of container size. For the fertilized 656 cm³ container treatment, 78%–85% of seedlings had phyllodes, with mean values increasing by fertilizer rate. Phyllodes are known to confer greater drought resistance than true leaves in koa, which may help to explain the improved survival of fertilized trees on this relatively dry site. Overall, nursery fertilization was more influential on seedling height and diameter response than container size after outplanting. However, the largest container (656 cm³) with the addition of fertilizer, produced significantly larger trees than all other treatments during the early regeneration phase; early growth differences tended to fade at 10 years due to inter-tree canopy competition. Although koa is able to fix atmospheric nitrogen through rhizobium associations, our data confirm the importance of nursery fertilization in promoting regeneration establishment. Nursery cultural techniques may play an important role in forest restoration of dry tropical sites invaded by exotic vegetation. Full article

Manipulation of planting density and choice of variety are effective management components in any cropping system that aims to enhance the balance between environmental resource availability and crop requirements. One-time fertilization at first flower with a medium plant stand under late sowing has not yet been attempted. To fill this knowledge gap, changes in leaf structural (stomatal density, stomatal length, stomata width, stomatal pore perimeter, and leaf thickness), leaf gas exchange, and chlorophyll fluorescence attributes of different cotton varieties were made in order to change the planting densities to improve lint yield under a new planting model. A two-year field evaluation was carried out on cotton varieties—V₁ (Zhongmian-16) and V₂ (J-4B)—to examine the effect of changing the planting density (D₁, low, 3 × 10⁴; D₂, moderate, 6 × 10⁴; and D₃, dense, 9 × 10⁴) on cotton lint yield, leaf structure, chlorophyll fluorescence, and leaf gas exchange attribute responses. Across these varieties, J-4B had higher lint yield compared with Zhongmian-16 in both years. Plants at high density had depressed leaf structural traits, net photosynthetic rate, stomatal conductance, intercellular CO₂ uptake, quenching (qP), actual quantum yield of photosystem II (ΦPSII), and maximum quantum yield of PSII (F_v/F_m) in both years. Crops at moderate density had improved leaf gas exchange traits, stomatal density, number of stomata, pore perimeter, length, and width, as well as increased qP, ΦPSII, and F_v/F_m compared with low- and high-density plants. Improvement in leaf structural and functional traits contributed to 15.9%–10.7% and 12.3%–10.5% more boll m⁻², with 20.6%–13.4% and 28.9%–24.1% higher lint yield averaged across both years, respectively, under moderate planting density compared with low and high density. In conclusion, the data underscore the importance of proper agronomic methods for cotton production, and that J-4B and Zhongmian-16 varieties, grown under moderate and lower densities, could be a promising option based on improved lint yield in subtropical regions. Full article

High input costs combined with multiple management and material inputs have threatened cotton productivity. We hypothesize that this problem can be addressed by a single fertilization at flowering with late sowing in a moderately populated plant stand. Field experiments were conducted to evaluate the cotton biomass accumulation, phosphorus dynamics, and fiber quality under three planting densities (low, 3 × 10⁴; moderate, 6 × 10⁴; and dense, 9 × 10⁴ ha⁻¹) and two cultivars (Zhongmian-16 and J-4B). High planting density had 6.2 and 12.6% larger stems and fruiting nodes m⁻², while low density produced a 37.5 and 59.4% maximum height node ratio. Moderate density produced 26.4–15.5%, 24.7–12.6%, and 10.5–13.6% higher biomass accumulation rate at the peak bloom, boll set, and plant removal stages over low and high density in both years, respectively. J-4B produced a higher reproductive organs biomass yield when compared with Zhongmian-16 in both years. This higher biomass formation was due to both the higher average (0.8 V_T kg·ha⁻¹·d⁻¹) and maximum (1.0 V_M kg·ha⁻¹·d⁻¹) reproductive organ phosphorus uptake, respectively. Plants with low density had 5.3–18.5%, 9.5–15%, and 7.8–12.8% greater length, strength, and micronaire values over moderate and dense plants, respectively. Conclusively, moderate density with J-4B is a promising option for improved biomass, phosphorus acquisition, and fiber quality under a short season. Full article

Forest managers are often required to restore forest stands following natural disturbances, a situation that may become more common and more challenging under global change. In parts of Central Europe, particularly in mountain regions dominated by mixed temperate forests, the use of relatively low intensity, uneven-aged silviculture is a common management approach. Because this type of management is based on mimicking less intense disturbances, the restoration of more severe disturbance patches within forested landscapes has received little attention. The goal of this paper is to synthesize research on the restoration of forests damaged by disturbances in temperate forests of Slovenia and neighbouring regions of Central Europe, where uneven-aged silviculture is practiced. Research indicates that active management aimed at favouring mixed uneven-aged forest reduces the risk of disturbance and improves the resilience of stands. Salvage logging may have positive or negative effects on regeneration, much of which is due to the method applied and the quality of work. The most prominent factors that negatively affect restoration are: lack of advanced regeneration and decomposed woody debris, high altitude, steep slopes, dense ground vegetation, and overbrowsing. Planting or sowing should be applied in post-disturbance forests where many negative factors interact and where a high demand for sustainability of forest ecosystem services is present. Full article