Rice Genomics and Genetics 2024, Vol.15, No.1, 36-47 http://cropscipublisher.com/index.php/rgg 38 Figure 1 Morphological and physiological characteristics of rice under heat stress (Adopted from Xu et al., 2021) High temperature stress has a negative impact on rice leaves, which are the main organs for photosynthesis. However, under high temperatures, leaves are damaged, manifesting as chlorosis, wilting, scorch, and necrosis. Damage to these leaves reduces the efficiency of photosynthesis, resulting in inefficient conversion of light energy into biomass, thereby affecting yields. At the same time, leaf damage also reduces leaf surface area, reduces photosynthetic potential, and exacerbates yield decline (Gautam et al., 2022). High temperature is usually accompanied by drought or high-temperature evaporation, which intensifies the degree of water stress. Under high-temperature conditions, rice is more likely to lose water, which increases the risk of dehydration of the plant. Dehydration affects the root system's ability to absorb water and nutrients, limiting plant growth. At the same time, under high temperature conditions, the transpiration rate of plants increases, resulting in a large amount of water loss. This water stress not only reduces yield, but also makes plants more susceptible to osmotic stress, adversely affecting cell stability. High temperature stress will also affect the absorption and transportation of nutrients in rice. Key nutrients, such as nitrogen, phosphorus and potassium, are crucial for the normal growth of rice. However, under high temperature conditions, the root structure and function of plants are damaged, limiting the absorption of these elements. In addition, high temperatures may interfere with the transport of these elements, resulting in uneven nutrient distribution, affecting plant health and yield. These effects further exacerbate the adverse effects of high temperature stress on rice yield. 2.2 Temperature-sensitive stages of rice and classification of high-temperature stress The growth and development of rice have different sensitivities to temperature at different growth stages. The seedling stage of rice is usually within the first few weeks after emergence. Seedlings at this stage are particularly sensitive to high temperatures because their growth points and reproductive organs have not yet been fully developed. development. Leaves are susceptible to sunburn in hot conditions, especially in full sunlight. When the
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