Legume Genomics and Genetics 2025, Vol.16, No.6, 297-312 http://cropscipublisher.com/index.php/lgg 302 drop in pod setting rate under continuous rain conditions, showing high sensitivity; while other varieties are relatively tolerant to low light and high humidity environments, and are called shade-tolerant or humidity-tolerant varieties (Zaman et al., 2025). Highly sensitive varieties often have the characteristics of fast growth and lush plant shape. They have high yields under normal conditions, but are prone to leggy growth and lodging, and serious flower drop when encountering insufficient light. For example, some high-yield pea varieties require sufficient sunlight for normal pollination and pod formation. Once they experience continuous rain, their pod setting rate drops significantly. Shade-tolerant varieties usually have relatively short and strong plants, thick and hard stems, thin leaves, and strong ability to utilize weak light. These varieties can still maintain relatively stable photosynthesis under low light, are not prone to leggy growth and lodging, and are less affected by pod formation in continuous rain. The experiment compared the performance of multiple pea varieties under low light treatment and found that the chlorophyll content of shade-tolerant varieties was less sensitive to changes in light intensity, and the photosynthetic efficiency decreased less, while the photosynthetic rate of sensitive varieties decreased significantly (Wu et al., 2020). In addition, the flower organs of shade-tolerant peas are also more adaptable to high humidity. Some varieties have smaller corollas and shorter flowering periods, which can reduce the chance of pathogen infection. On the contrary, highly sensitive varieties often have large and long-lasting corollas, and are more susceptible to gray mold and other diseases when it rains during flowering (Su et al., 2023). In addition to tolerance to low light, highly disease-resistant varieties also have an advantage in continuous rain. Even in a humid environment, the flower pods of some pea varieties resistant to gray mold are not easily infected, and the pod setting rate can be maintained. Shade-tolerant and humidity-tolerant varieties usually have: compact plant type, strong resistance to lodging, higher leaf photosynthetic efficiency and the proportion allocated to reproductive growth, and resistance to major flowering diseases. These characteristics give them a relatively stable pod-setting ability in adverse conditions such as continuous rain. Current breeding work also pays more and more attention to the stress resistance of peas, and some new strains suitable for planting under rainy conditions have been selected, which provides a possibility for increasing yields in adverse climates. 4.2 Correlation between varieties’ pod set rate and rainy periods Through field trials and multi-point monitoring, the differences in pod setting rate changes of different pea varieties under continuous rainy weather can be quantified. A study compared the pod setting performance of multiple pea varieties under continuous rainy conditions, and the results showed that there were extremely significant differences in the decline in pod setting rate among varieties: the pod setting rate of sensitive varieties decreased by more than 50% compared with normal weather, while the pod setting rate of shade-tolerant varieties only decreased by about 20% (Zaman et al., 2025). This shows that variety characteristics are highly correlated with the degree of damage caused by continuous rain. A study on waterlogging tolerance of leguminous crops also supports this point: after 14 days of flooding, the yield difference between the two pea varieties was more than twice, and the ability of the waterlogged variety to recover growth was significantly stronger than that of the sensitive variety. Although this study is aimed at waterlogging stress, the excessive soil moisture caused by continuous rain is similar to mild waterlogging, and its variety difference trend is of reference significance. Similarly, in terms of light stress, flowering and podding of different pea genotypes respond differently to reduced sunlight. It has been reported that under shading treatment, the flowering period of some pea varieties was delayed by 7 days and the pod setting rate was reduced by 30%, while the flowering period of another shade-tolerant variety was only delayed by 2 days and the pod setting rate was almost unaffected (Naveed et al., 2024). Through correlation analysis, it was found that the high-yield potential of varieties under normal conditions is not completely positively correlated with their relative yield under rainy conditions. Some high-yield varieties have obvious advantages in good weather, but they suffer serious yield reductions when encountering continuous rain; on the contrary, some stable varieties with medium yields usually perform relatively well in rainy weather. Therefore, for rainy and low-light climates, varieties with good stability should be selected. The interannual fluctuations in the pod setting rate of pea varieties are significantly correlated with the number of rainy days in the year: in years with many rainy days, the pod setting rate of sensitive varieties decreases significantly, while the
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