Legume Genomics and Genetics 2025, Vol.16, No.6, 297-312 http://cropscipublisher.com/index.php/lgg 300 the podding process may be disturbed. Secondly, temperature affects pollen vitality and fertilization. The suitable flowering temperature for peas is generally in the range of 15 ℃~25 ℃. If continuous rain is accompanied by low temperatures, the activity of flower organs will decrease, which is not conducive to normal pollination and fertilization. Thirdly, soil moisture conditions also play an important role in root function and pod development. When the soil is too wet, the root respiration is restricted and the absorption capacity is reduced, and the plant may experience physiological hypoxia and nutrient absorption disorders. Excessive water can also easily cause root rot and other diseases, weakening the plant's ability to supply pods and leading to a decrease in the pod setting rate. Continuous rain is usually accompanied by air humidity close to saturation, which is conducive to the germination of pathogen spores and infection of floral organs. In particular, moisture-loving diseases such as gray mold are easy to spread during the flowering period, directly infecting flowers and causing rot, which seriously hinders fertilization and pod formation. Therefore, external environmental factors often affect pea pod setting in combination: rainy and low light not only reduce photosynthetic products but also breed diseases, and the dual effects of low temperature and high humidity make the pea reproductive process face multiple stresses. In actual research and production, it is necessary to comprehensively consider these environmental factors and improve the pod setting rate of peas in adverse weather by improving cultivation conditions (such as supplementary light, moisture drainage, etc.). 3 Effects of Continuous Rain on Pod Set Rate 3.1 Light deficiency and limitations on photosynthetic capacity The first direct impact of continuous rainy weather is severe lack of light. Continuous cloudy days and cloud cover cause a sharp decrease in solar radiation, and the photosynthesis level of pea plants is significantly reduced. The assimilates produced by photosynthesis are the material basis for the growth of pods and seeds. When the supply of photosynthetic products is insufficient, the plant will give priority to its own nutritional growth, and the allocation to reproductive organs will be relatively reduced (Naveed et al., 2024). Experiments have shown that under weak light conditions, plants often change the proportion of photosynthetic product distribution, with more allocated to nutritional organs such as stems and leaves, while the proportion allocated to fruits is reduced, which will directly lead to a decrease in pod setting rate and a decrease in the number of grains per pod. Specifically for peas, the number of sunshine hours during continuous rainy periods is relatively small. If it coincides with the flowering period of peas, the nutrients produced by the plant will not be able to meet the development needs of all young pods. Many surveys have recorded the phenomenon of a large number of pea flowers and pods falling due to rainy weather. Insufficient light can also cause morphological changes in pea plants, such as elongated stems and leaves, thinning leaves, and increased plant height, which indirectly affects pod setting. For example, under low light, the internodes of pea plants elongate and become tall and thin, and they are prone to lodging and shading. The lower part of the plant lacks light, forming a vicious cycle (Zhao et al., 2019). Due to limited light, the lower flower position often blooms but cannot pod, or the small pods that are produced quickly turn yellow and fall off. These factors work together to significantly reduce the pod setting rate of peas under continuous rainy and low-light conditions. Studies have pointed out that under shading stress, the flowering and fruiting of different crops are generally affected. For example, reduced light will delay the flowering of peas by about 9% to 15%, delay the pod setting time, and reduce the number of effective pods. Therefore, insufficient light caused by continuous rain is one of the primary reasons for the decline in the pod setting rate of peas. To address this problem, measures such as supplementary light and reasonable dense planting need to be taken to minimize the limitation of weak light on pea photosynthesis. 3.2 Excessive soil moisture and suppression of root function Long-term precipitation during continuous rainy periods can lead to excessive soil moisture in the field, and even waterlogging, which seriously affects the normal function of the pea root system. Peas are taproot crops, and their roots are very sensitive to soil aeration. When the soil is close to saturation, the oxygen content in the pores decreases, the root respiration is restricted, and the root absorption of water and mineral nutrients is inhibited (Zaman et al., 2025). Especially in the flowering and pod-setting stage, peas require more water and fertilizer. If the root vitality decreases due to waterlogging stress, the aboveground part of the plant is prone to nutrient
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