Rice yield and grain quality are highly sensitive to salinity stress. Salt-tolerant/susceptible rice cultivars respond to salinity differently. To explore the variation in grain yield and quality to moderate/severe salinity stress, five rice cultivars differing in degrees of salt tolerance, including three salt-tolerant rice cultivars (Lianjian 5, Lianjian 6, and Lianjian 7) and two salt-susceptible rice cultivars (Wuyunjing 30 and Lianjing 7) were examined. Grain yield was significantly decreased under salinity stress, while the extent of yield loss was lesser in salt-tolerant rice cultivars due to the relatively higher grain filling ratio and grain weight. The milling quality continued to increase with increasing levels. There were genotypic differences in the responses of appearance quality to mild salinity. The appearance quality was first increased and then decreased with increasing levels of salinity stress in salt-tolerant rice but continued to decrease in salt-susceptible rice. Under severe salinity stress, the protein accumulation was increased and the starch content was decreased; the content of short branched-chain of amylopectin was decreased; the crystallinity and stability of the starch were increased, and the gelatinization temperature was increased. These changes resulted in the deterioration of cooking and eating quality of rice under severe salinity-stressed environments. However, salt-tolerant and salt-susceptible rice cultivars responded differently to moderate salinity stress in cooking and eating quality and in the physicochemical properties of the starch. For salt-tolerant rice cultivars, the chain length of amylopectin was decreased, the degrees of order of the starch structure were decreased, and pasting properties and thermal properties were increased significantly, whereas for salt-susceptible rice cultivars, cooking and eating quality was deteriorated under moderate salinity stress. In conclusion, the selection of salt-tolerant rice cultivars can effectively maintain the rice production at a relatively high level while simultaneously enhancing grain quality in moderate salinity-stressed environments. Our results demonstrate specific salinity responses among the rice genotypes and the planting of salt-tolerant rice under moderate soil salinity is a solution to ensure rice production in China.

The number of effective rice tillers determines the number of effective panicles and then affects the final yield. Rice tillering ability shows great differences among cultivars and under different environmental conditions, but the underlying mechanisms are not clear. The present paper investigated the formation of rice tillers and examined its genetic regulation, the effects of plant hormones, several environmental factors affecting rice tillering, and nitrogen’s regulation of tillers. Finally, the utilization of the tillering ability of weedy and wild rice was investigated. We concluded that many genes are involved in manipulating rice tillering, including MOC1, MOC3, FON1, LAX1, LAX2, APC/C^TE, D3, D10, D14, D17, D27, and D53, by altering associated hormone contents or coding signal substances. The plant hormones auxin (IAA), gibberellin (GA), and strigolactone (SL) inhibit rice tillering, while cytokinin (CTK) promotes rice tillering. Weak light (light intensity is lower than 200 μmol m⁻² s⁻¹) and low and high temperatures (below 15 °C and above 38 °C) inhibit rice tillering, while optimized water management, such as alternate wetting and moderate drying irrigation, can greatly promote rice tillering. In addition, increasing plant nitrogen concentration can effectively improve rice tillers by adjusting multiple nitrogen metabolism enzymes. Weedy rice and some wild rice showed obvious superiority in tillering ability with respect to cultivated rice, but the underlying mechanisms are not clear and should be further explored. This study can provide theoretical guidance for the breeding and cultivation of high-yield and high-efficiency rice cultivars.

The number of maize seedlings is a key determinant of maize yield. Thus, timely, accurate estimation of seedlings helps optimize and adjust field management measures. Differentiating “multiple seedlings in a single hole” of maize accurately using deep learning and object detection methods presents challenges that hinder effectiveness. Multivariate regression techniques prove more suitable in such cases, yet the presence of weeds considerably affects regression estimation accuracy. Therefore, this paper proposes a maize and weed identification method that combines shape features with threshold skeleton clustering to mitigate the impact of weeds on maize counting. The threshold skeleton method (TS) ensured that the accuracy and precision values of eliminating weeds exceeded 97% and that the missed inspection rate and misunderstanding rate did not exceed 6%, which is a significant improvement compared with traditional methods. Multi-image characteristics of the maize coverage, maize seedling edge pixel percentage, maize skeleton characteristic pixel percentage, and connecting domain features gradually returned to maize seedlings. After applying the TS method to remove weeds, the estimated R² is 0.83, RMSE is 1.43, MAE is 1.05, and the overall counting accuracy is 99.2%. The weed segmentation method proposed in this paper can adapt to various seedling conditions. Under different emergence conditions, the estimated R² of seedling count reaches a maximum of 0.88, with an RMSE below 1.29. The proposed approach in this study shows improved weed recognition accuracy on drone images compared to conventional image processing methods. It exhibits strong adaptability and stability, enhancing maize counting accuracy even in the presence of weeds.

Six cultivated rice genotypes showing different stomatal conductance (g_s) values were used to investigate the influence of leaf vein traits on leaf gas exchange and leaf hydraulics. The results showed that g_s was the main determinant of the varietal difference in the net photosynthetic rate (P_N), whereas the area-based leaf nitrogen content (N_area) and mesophyll conductance (g_m) were not main factors. g_s and P_N were both positively correlated with leaf hydraulic conductance (K_leaf). A high density of leaf veins (vein length per leaf area, VLA), especially minor leaf veins (VLA_minor), was of benefit for improving the K_leaf. The proportion of the minor leaf vein length to the total leaf vein length did not impact the leaf hydraulics or leaf gas exchange. Overall, these findings suggested that a high density of leaf veins, especially minor leaf veins, enhances K_leaf and promotes g_s and P_N in cultivated rice genotypes and a high VLA can be regarded as a high photosynthetic capacity trait in rice plants.

Excessive nitrogen fertilization poses a threat to agricultural sustainability. Achieving high crop yield while improving soil health under reduced nitrogen (N) input is a global concern. This two-year rice-wheat rotation study was designed with two N fertilizer levels (conventional N level and reduced N level) and four controlled-release urea (CRU) application modes, along with a control CK (farmer’s conventional fertilization mode). Effects on yield, nitrogen use efficiency (NUE), and soil fertility were compared. Polymer-coated urea (PCU) was employed as the CRU material in this study. Significantly lower annual yields were observed under sole PCU. The PCU + U treatments increased yields by 9.16–15.00% over CK. The highest rice-wheat yield and nitrogen recovery efficiency occurred with 40% PCU + 30% U basal fertilizer + 30% U panicle fertilizer application mode. Nitrogen reduction decreased yield and plant nitrogen but improved nitrogen recovery efficiency. However, the RN-PCU + U mode achieved yields comparable to CK. RN-PCU + U treatments provided stable yields and higher economic benefits, with the latter increasing by 6.3-35.7% compared to CK. Soil nutrient content varied significantly among PCU application modes. The RN 70% PCU + 30% U basal fertilizer showed the best performance on soil fertility: organic matter content was 2.9% higher than CK, and total nitrogen was 9.3% higher than CK after two rice-wheat rotations. Panicle fertilizer enhanced nutrient uptake and reduced residual soil nutrient levels. Correlation analysis indicated that increased plant N and soil available phosphorus were associated with higher yields, whereas elevated soil alkali-hydrolyzed N content promoted organic matter accumulation. PCU + U application can compensate for the decrease of rice-wheat yield under nitrogen reduction and improve the activity of soil nutrients. Our results suggest that the 70% PCU + 30% U basal application mode optimizes nitrogen efficiency, sustains rice-wheat yields, and enhances soil fertility under reduced nitrogen input. These findings could inform future sustainable agricultural practices designed to reduce nitrogen use while maintaining crop yield.