Temperature is a critical environmental factor affecting the growth and development of rice, especially under the backdrop of global climate change, where temperature fluctuations have become increasingly significant in influencing the growth cycle and development rate of rice. To comprehensively assess the impact of temperature variations on the different growth stages of rice, this study integrates data from multiple relevant studies published between 1980 and 2024. By selecting research focused on the influence of temperature changes on the rice development cycle, a meta-analysis is conducted to systematically evaluate the effects of temperature on the growth rates of rice during its six key developmental stages. The results indicate that increased temperatures significantly accelerate the development rate of rice during all growth stages, with a general acceleration in growth speed at different developmental phases. The study further found that when the temperature ranges from 28 °C to 32 °C, the growing conditions for rice are most favorable, exhibiting the optimal development rate. This study provides scientific evidence for understanding how temperature changes affect rice growth and development and offers valuable references for rice cultivation management and climate adaptation strategies.

Introduction: Oryza sativa is one of the most important cereal crops globally.Methods: The aim of this study was to map areas suitable for the growth and conservation of O. sativa under current and future climatic conditions, and to observe the effects of UV variables on the distribution area of O. sativa.Results: Based on species distribution records, we used the Biomod2 platform to combine climate data, future shared socioeconomic pathways, and elevation data. The ensemble model (EM) was constructed by screening multiple species distribution models (SDMs), including RF, GBM, ANN, and MARS. The ROC value of the joint model is greater than 0.95, indicating that the model has high reliability and accuracy. Mean annual temperature (bio01), temperature seasonality (bio04), minimum temperature in the coldest month (bio06), mean temperature of coldest quarter (bio11), human footprint and human activity impact index (hfv2geo1) and annual average ultraviolet radiation (uvb1annualmeanuv.b) were the most important environmental variables affecting the suitable distribution area of O. sativa. Under the current climate conditions, the suitable habitats of O. sativa are mainly distributed in the south of the Yangtze River. In the future climate scenario, the total suitable habitat area of O. sativa tended to decrease, but the suitable distribution area under the influence of UV was larger than that without UV.Discussion: Climate change will significantly affect the potential distribution of O. sativa in China and increase its extinction risk. Therefore, it is necessary to provide a reference for the conservation, management, introduction and cultivation of food crops in China.

Drought stress is a major environmental factor that adversely affects plant growth and development. Spermidine (SPD), a polyamine, plays a critical role in plant defense mechanisms against drought stress. PEG was used to simulate osmotic stress, which mimics drought conditions under controlled environments. This study investigated the effects of exogenous spermidine (SPD) on the physiological and biochemical responses of mango plants under drought stress and explored its potential mitigation mechanisms. Two-year-old ‘Renong 1’ mango seedlings were subjected to drought stress induced by polyethylene glycol (PEG 6000) at concentrations of 5%, 15%, and 25%, simulating mild, moderate, and severe drought conditions, respectively. Plants were subsequently treated with 1 mmol/L spermidine. After PEG 6000 treatment and spermidine application for 3 days, the leaf morphology, relative chlorophyll content, malondialdehyde (MDA) levels, antioxidant enzyme activities (superoxide dismutase [SOD], peroxidase [POD], catalase [CAT]), and osmotic regulators (proline, soluble sugars, and soluble proteins) were analyzed. The results demonstrated that drought stress caused leaf chlorosis, desiccation, reduced relative chlorophyll content, elevated MDA levels (indicating lipid peroxidation), enhanced antioxidant enzyme activities, increased proline and soluble sugar accumulation for osmotic regulation, and decreased soluble protein content. Exogenous spermidine treatment significantly alleviated drought-induced damage by reducing leaf chlorosis, delaying relative chlorophyll degradation (by 20.0–25.7% under moderate drought and 14.1–19.1% under severe drought), and decreasing MDA levels (by 4.8–9.5% under moderate drought and 0.8–23.7% under severe drought). Furthermore, spermidine enhanced antioxidant enzyme activities (e.g., SOD activity increased by 24.9–37.4% and POD by 74.0–104.0% under moderate drought), regulated osmotic substance accumulation (e.g., proline decreased by 21%, 26%, and 24% under mild, moderate, and severe drought, respectively), and mitigated the reduction in soluble protein content (by 6.6% under moderate drought and 10.3% under severe drought). In conclusion, exogenous spermidine mitigates drought-induced damage in mango by preserving photosynthetic capacity, enhancing the antioxidant defense system, and modulating osmotic balance. These results showed that SPD could significantly improve plant vigor or survival rate under stress. It provides a theoretical basis for water-saving cultivation of mango, improving the stress resistance of mango varieties and the application of spermidine in tropical fruit production.