Legume Genomics and Genetics 2025, Vol.16, No.6, 297-312 http://cropscipublisher.com/index.php/lgg 298 for a long time, local continuous rain is prone to occur (Lee et al., 2023). In recent years, extreme precipitation events have increased under the background of climate change, and the frequency and duration of continuous rainy weather in some areas have shown an upward trend. For example, the Sichuan Basin and Jiangnan region have experienced continuous rain for more than ten days, which has had a serious impact on agricultural production. Continuous rain usually leads to reduced light, near-saturated relative humidity, and may cause low temperature and low light. The combination of these meteorological conditions is extremely unfavorable for crop growth (Bai et al., 2025). This study will explain the main physiological mechanisms of pea pod setting, including key physiological processes, endogenous hormone regulation and environmental factors, analyze the specific manifestations and causes of reduced pea pod setting rate under continuous rain conditions, and compare the response differences of different pea varieties under continuous rain from three aspects: insufficient light, excessive soil moisture, and increased pathogens. The characteristics and practical application value of highly sensitive and shade-tolerant varieties are clarified, and the indirect agronomic effects of continuous rain, such as outbreaks of pests and diseases, disordered fertilization management rhythm, and poor field ventilation, are discussed. Through typical cases in Qiubei, Yunnan, Dingxi, Gansu, and the central mountainous areas of Guizhou, the practical experience of coping with continuous rain disasters is introduced and analyzed. By revealing the physiological and ecological mechanism of changes in pea pod setting rate under continuous rainy conditions, this study hopes to improve the stable yield capacity of pea and other grain and bean crops, and ensure my country's food security and sustainable agricultural development. 2 Physiological Mechanisms of Pea Pod Setting 2.1 Key physiological processes during pod set stage The pod setting stage of pea refers to the process in which the ovary develops into pods after the flower organs are fertilized, including continuous links such as flowering, pollination, fertilization, and the development of young pods and seeds. First, pea is a closed-pollinated crop, and its flowers can complete self-pollination before opening; successful pollination and fertilization are necessary conditions for starting pod development. After fertilization occurs, the division and elongation of ovary cells are activated, and the ovary begins to expand rapidly to form young pods, at which time the ovules also develop into seeds. Studies have shown that in most angiosperms, if the ovules are not fertilized, the ovary usually does not develop further, and the plant will actively terminate the organ growth of the flower to avoid wasting resources. The same is true for peas. Unfertilized pea flowers are prone to fall off or stop developing, so the pod setting rate depends largely on the success rate of pollination and fertilization. Secondly, during the young pod formation stage, there is a close exchange of substances and signals between the pods and the seeds inside (Figure 1) (Bal and Østergaard, 2022). Developing seeds can generate growth signals to promote pod development, and pods provide nutrients for seeds and regulate their growth. The two work together to ensure the normal formation of pea fruits. If environmental stress causes any of these links to be blocked, such as pollination and fertilization failure or lack of nutrient support for young pods, it may cause pod development to stagnate or young pods to fall off, thereby reducing the pod setting rate. It can be seen that the pea pod setting stage is a process that is very sensitive to the internal and external environment. It requires not only the coordinated supply of internal hormones and substances, but also relies on suitable external conditions to ensure the smooth progress of pollination, fertilization and young pod development. 2.2 Influence of hormonal regulation on pod formation Plant hormones play an important regulatory role in the pea pod setting process. Studies have shown that hormones such as auxin (IAA) and gibberellin (GA) accumulate rapidly after pollination and fertilization, which helps ovary expansion and pod growth (Miryeganeh, 2022). Especially in pea and other Fabaceae crops, seeds will produce a large number of auxin signals after fertilization, including a special chlorinated auxin (4-Cl-IAA), which is abundant in pea fruit and seed tissues and is believed to be related to the promotion of pod elongation. Auxin releases the inhibition of growth-related genes through signaling pathways, thereby triggering cell division and elongation, and plays a key role in pod formation (Bal and Østergaard, 2022). In addition to auxin,
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