Much attention has shifted to the effects of temperature and solar radiation on rice production and grain quality due to global climate change. Meanwhile, lodging is a major cause of rice yield and quality losses. However, responses of the lodging resistance of rice to temperature and solar radiation are still unclear. To decipher the mechanisms through which the lodging resistance might be affected by temperature and solar radiation, 32 rice cultivars with different lodging resistance were grown at two eco-sites on three sowing dates over a period of three years. Based on the field observation, 12 indica rice cultivars which did not lodge were selected for analysis. Significant differences were found in the lodging resistance of the indica rice cultivars at different temperature and solar radiation treatments. The results showed that temperature was the main factor that affected the lodging resistance of indica rice cultivars under the conditions of this study. With the increased average daily temperature, the lodging resistance decreased rapidly, primarily due to the significant reduction in physical strength of the culm, which was attributed to the longer and thinner basal second internode. Among the 12 indica rice cultivars, the lodging-moderate cultivar Chuanxiang 29B was most sensitive to temperature, and the lodging-resistant cultivar Jiangan was least responsive to temperature. These results suggested that rice breeders could set the shorter and thicker basal internode as the main selection criteria to cultivate lodging-resistant indica cultivars to ensure a high yield at a higher ambient temperature.

Climate is the most important environmental factor influencing yield during rice growth and development. To investigate the relationships between climate and yield under different crop rotation patterns and planting methods, three typical rotation patterns (vegetable–rice (V), rape–rice (R), and wheat–rice (W)) and two mechanical planting methods (mechanical transplanting (T1) and mechanical direct seeding (T2)) were established. The results showed that compared to the V rotation pattern, the average daily temperature (ADT) during the sowing to heading stage increased under both R and W rotation patterns, which significantly shortened the growth period. Thus, the effective accumulated temperature (EAT), photosynthetic capacity, effective panicle (EP), and spikelet per panicle (SP) under R and W rotation patterns significantly decreased, leading to reductions in grain yield (GY). VT2 had a higher ratio of productive tillers (RPT), relative chlorophyll content (SPAD), leaf area index (LAI), and net photosynthetic rate (Pn) than those of VT1, which significantly increased panicle dry matter accumulation (DMA), resulting in an increase in GY. Although RT2 and WT2 had a higher RPT than those of RT1 and WT1, the GY of RT1 and WT1 decreased due to the significant reductions in EAT and photosynthetic capacity. Principal component analysis (PCA) showed that the comprehensive score for different rotation patterns followed the order of V > R > T with VT2 ranking first. The structural equation model (SEM) showed that EAT and ADT were the most important climate factors affecting yield, with total effects of 0.520 and −0.446, respectively. In conclusion, mechanical direct seeding under vegetable–rice rotation pattern and mechanical transplanting under rape–rice or wheat–rice rotation pattern were the rice-planting methods that optimized the climate resources in southwest China.

Potassium plays a critical role in improving rice yield and quality; however, the effects of delayed K application on grain protein metabolism and eating quality remain unclear. This study evaluated four potassium fertilizer management modes designed with basal fertilizer: panicle fertilizer, with ratios of 10:0 (K1, control), 8:2 (K2), 6:4 (K3), and 4:6 (K4). Grain protein and protein fractions, free amino acids (FAA), key protein synthesis enzyme activities, starch RVA profile, taste value, processing and appearance quality, and yield were measured. With the delayed application of potassium fertilizer, grain GS, and GOGAT activities decreased by 3.15–7.67% and 6.92–13.06%, while GOT and GPT activities declined by 3.72–13.99% and 2.94–3.32% compared with K1. Consequently, FAA, albumin, globulin, prolamin, and glutelin contents all decreased, and grain protein content was significantly reduced, by 0.18–0.44 percentage points. In contrast, peak viscosity and breakdown increased, setback decreased, and taste value improved by 4.35–10.14%. Meanwhile, head rice rate increased, chalky grain rate and chalkiness decreased, and yield under K4 treatment increased significantly by 3.48%. Delayed potassium fertilizer application (K4 treatment) helps to reduce the activity of key enzymes involved in protein synthesis, decrease protein and its component contents, while simultaneously improving yield and eating quality.