Introduction Controlled-release fertilizers effectively improve crop yield and nitrogen use efficiency (NUE). However, their use increases the cost of crop production. Optimal management modes involving urea replacement with controlled-release N fertilizers to increase rice yield through enhanced NUE are not widely explored. Methods Field experiments were conducted from 2017 to 2018 to determine the effects of different controlled-release N fertilizers combined with urea [urea-N (180 kg ha -1 , N 1 )]. We used controlled-release N (150 kg ha -1 , N 2 ) as the base, and four controlled-release N and urea-N ratio treatments [(80%:0% (N 3 ), 60%:20% (N 4 ), 40%:40% (N 5 ), or 20%:60% (N 6 ) as the base with 20% urea-N as topdressing at the panicle initiation stage under 150 kg ha -1 ] to study their impact on the grain yield and NUE of machine-transplanted rice. Results and discussion Grain yield and NUE were positively correlated with increases in photosynthetic production, flag leaf net photosynthetic rate ( P n ), root activity, N transport, and grain-filling characteristics. The photosynthetic potential and population growth rate from the jointing to the full-heading stage, highly effective leaf area index (LAI) rate and P n at the full-heading stage, root activity at 15 d after the full-heading stage, and N transport in the leaves from the full-heading to mature stage were significantly increased by the N 4 treatment, thereby increasing both grain yield and NUE. Furthermore, compared with the other N treatments, the N 4 treatment promoted the mean filling rate of inferior grains, which is closely related to increased filled grains per spikelet and filled grains rate. These effects ultimately improved the grain yield (5.03-25.75%), N agronomic efficiency (NAE, 3.96-17.58%), and N partial factor productivity (NPP, 3.98-27.13%) under the N 4 treatment. Thus, the N 4 treatment with controlled-release N (60%) and urea-N (20%) as a base and urea-N (20%) as topdressing at the panicle-initiation stage proved effective in improving the grain yield and NUE of machine-transplanted hybrid indica rice. These findings offer a theoretical and practical basis for enhancing rice grain yield, NUE, and saving the cost of fertilizer.
Nitrogen (N) fertilizer management, especially postponing N topdressing can affect rice eating quality by regulating starch quality of superior and inferior grains, but the details are unclear. This study aimed to evaluate the effects of N topdressing on starch structure and properties of superior and inferior grains in hybrid indica rice with different tastes and to clarify the relationship between starch structure, properties, and taste quality.Two hybrid indica rice varieties, namely the low-taste Fyou 498 and high-taste Shuangyou 573, were used as experimental materials. Based on 150 kg·N hm-2, three N fertilizer treatments were established: zero N (N0), local farmer practice (basal fertilizer: tillering fertilizer: panicle fertilizer=7:3:0) (N1), postponing N topdressing (basal fertilizer: tillering fertilizer: panicle fertilizer=3:1:6) (N2).The starch granules of superior grains were more complete, and the decrease in small granules content and the stability of starch crystals were a certain extent less than those of inferior grains. Compared with N1, under N2, low-taste and high-taste varieties large starch granules content were significantly reduced by 6.89%, 0.74% in superior grains and 4.26%, 2.71% in inferior grains, the (B2 + B3) chains was significantly reduced by 1.61%, 0.98% in superior grains, and 1.18%, 0.97% in inferior grains, both reduced the relative crystallinity and 1045/1022 cm-1, thereby decreasing the stability of the starch crystalline region and the orderliness of starch granules. N2 treatment reduced the ΔHgel of two varieties. These changes ultimately contributed to the enhancement of the taste values in superior and inferior grains in both varieties, especially the inferior grains. Correlation analysis showed that the average starch volume diameter (D[4,3]) and relative crystallinity were significantly positively correlated with the taste value of superior and inferior sgrains, suggesting their potential use as an evaluation index for the simultaneous enhancement of the taste value of rice with superior and inferior grains.Based on 150 kg·N hm-2, postponing N topdressing (basal fertilizer: tillering fertilizer: panicle fertilizer=3:1:6) promotes the enhancement of the overall taste value and provides theoretical information for the production of rice with high quality.
Aims This study evaluated the impact of wheat straw return and microbial agent application on rice field environments. Methods Using Rice variety Chuankangyou 2115 and a microbial mix of Bacillus subtilis and Trichoderma harzianum . Five treatments were tested: T 1 (no straw return), T 2 (straw return), T 3 , T 4 , and T 5 (straw return with varying ratios of Bacillus subtilis and Trichoderma harzianum ). Results Results indicated significant improvements in rice root length, surface area, dry weight, soil nutrients, and enzyme activity across T 2 -T 5 compared to T 1 , enhancing yield by 3.81-26.63%. T 3 (50:50 microbial ratio) was optimal, further increasing root dry weight, soil enzyme activity, effective panicle and spikelet numbers, and yield. Dominant bacteria in T 3 included MBNT15 , Defluviicoccus , Ro kubacteriales, and Latescibacterota . Higher Trichoderma harzianum proportions (75% in T 5 ) increased straw decomposition but slightly inhibited root growth. Correlation analysis revealed a significant positive relationship between yield and soil microorganisms like Gemmatimonadota and Firmicutes at the heading stage. Factors like dry root weight, straw decomposition rate post-jointing stage, and elevated soil enzyme activity and nutrient content from tiller to jointing stage contributed to increased panicle and spikelet numbers, boosting yield. Conclusion The optimal Bacillus subtilis and Trichoderma harzianum ratio for straw return was 50:50, effectively improving soil health and synergizing high rice yield with efficient straw utilization.
Rice production is the agricultural activity with the highest energy consumption and carbon emission intensity. Water and fertilizer management constitutes an important part of energy input for rice production and a key factor affecting greenhouse gas emissions from paddy fields. Water–fertilizer integration management (AIM) is an automated water and fertilizer management system for large-scale rice production, which can effectively save water and fertilizer resources. At present, the energy utilization and environmental impact of AIM in rice production are not clear. To clarify whether AIM is a water and fertilizer management measure that combines energy conservation and carbon emission reduction, a comparative study between the widely used farmers’ enhanced water and fertilizer management (FEM) in China and AIM was conducted in this paper. Field experiments were conducted to evaluate the rice yield, carbon emission, energy utilization, and economic benefits of the two management methods. The results showed that AIM reduced water and fertilizer inputs, energy inputs, and economic costs by 12.18–28.57%, compared to FEM. The energy utilization efficiency, energy profitability, and energy productivity under AIM were improved by 11.30–12.61%. CH4 and N2O emissions and carbon footprint were reduced by 20.79%, 6.51%, and 16.39%, respectively. Compared with FEM, AIM can effectively improve the utilization efficiency of water and fertilizer resources and reduce carbon emissions. This study presents a mechanized water and fertilizer management approach suitable for large-scale rice production systems in China. By analyzing rice yield, resource utilization efficiency, and environmental benefits, AIM can serve as a crucial management strategy for enhancing productivity, economic returns, and environmental conservation within profitable rice production systems. In the future, further investigation into the impact of AIM on the microbial mechanisms underlying rice yield formation and greenhouse gas emissions is warranted.
Rice-rape, rice-wheat and rice-garlic rotations are common cropping systems in Southwest China and have played a significant role in ensuring ecological and economic benefits (EB) and addressing the challenges of China's food security in the region. But regionally, the crop yields in these rotation systems are 1.25%-14.73% lower than the national average. Intelligent decision-making with machine learning can analyze the key factors for obtaining better benefits, but it is rarely used to enhance the probability of obtaining such benefits of rotations in Southwest China. Thus, we used a data-intensive approach to construct intelligent decision-making with machine learning to provide strategies for improving the benefits of rice-rape, rice-wheat, and rice-garlic rotations in Southwest China. The results show that raising yield and partial fertilizer productivity (PFP) by increasing seed input under high fertilizer obtained optimal benefits with a 10% probability in rice-garlic system. Obtaining high yields and greenhouse gas (GHG) emissions by increasing N application and decreasing K application obtained suboptimal benefits with an 8% probability in rice-rape system. Reducing N and P to enhance PFP and yield obtained optimal benefits with the lowest probability (8%) in rice-wheat system. Based on the predictive analysis of a random forest model that decreases N by 25% and increases P and K by 8% and 74%, respectively, in rice-garlic system, that decreases N and K by 54% and by 36%, respectively, and increases P by 38% in rice-rape system, and that decreases N by 4% and increases P and K by 65% and 23% in rice-wheat system, these strategies could be further optimized by 17-34% for different benefits, all of these measures can improve the effectiveness of crop rotation systems to varying degrees. Overall, these findings provide insights into optimal agricultural inputs for higher benefits through an intelligent decision-making system with machine learning analysis in rice-rape, rice-wheat, and rice-garlic systems.
Introduction The use of controlled-release nitrogen (N) fertilizers has been shown to improve yield and N-use efficiency (NUE) in mechanical transplanted rice. However, the fertilizer requirements for mechanical direct-seeding rice differ from those for mechanical transplanted rice. The effects of controlled-release fertilizers on yield, NUE, and quality in mechanical direct-seeding rice are still unknown. Methods Hybrid indica rice varieties Yixiangyou 2115 and Fyou 498 were used as test materials, and slow-mixed N fertilizer (120 kg hm -2 ) as a base (N 1 ), N 1 +urea-N (30 kg hm -2 ) once as a base (N 2 ), N 1 +urea-N (30 kg hm -2 ) topdressing at the tillering stage (N 3 ), N 1 +urea-N (30 kg hm -2 ) topdressing at the booting stage (N 4 ) four N fertilizer management to study their impact on the yield, NUE and quality of mechanical direct-seeding rice. Results and discussion Compared with Yixiangyou 2115, Fyou 498 significantly increased photosynthetic potential, population growth rate, root vigor, and N transport rate by 3.34–23.88%. This increase further resulted in a significant improvement in the yield and NUE of urea-N topdressing by 1.73–5.95 kg kg -1 . However, Fyou 498 showed a significant decrease in the head rice rate and taste value by 3.34–7.67%. All varieties were treated with N 4 that significantly increase photosynthetic potential and population growth rate by 15.41–62.72%, reduce the decay rate of root vigor by 5.01–21.39%, promote the N transport amount in stem-sheaths (leaves) by 13.54–59.96%, and then significantly increase the yields by 4.45–20.98% and NUE of urea-N topdressing by 5.20–45.56 kg kg -1 . Moreover, the rice processing and taste values were optimized using this model. Correlation analysis revealed to achieve synergistic enhancement of high-yield, high-quality, and high-NUE in rice, it is crucial to focus on increasing photosynthetic potential, population growth rate, and promoting leaf N transport. Specifically, increasing the contribution rate of N transport in stem-sheaths is the most important. These findings offer an effective N management strategy for 4R nutrient stewardship (right source, right method, right rate and right timing) of mechanical direct-seeding hybrid indica rice.
'/%3e%3cuse xlink:href='%23a' transform='rotate(23.036 .093 25.536)'/%3e%3cuse xlink:href='%23a' transform='rotate(45.87 1.273 16.18)'/%3e%3cuse xlink:href='%23a' transform='rotate(69.945 .996 12.078)'/%3e%3cuse xlink:href='%23a' transform='rotate(20.66 -19.689 31.932)'/%3e%3c/svg%3e)