Legume Genomics and Genetics 2025, Vol.16, No.6, 297-312 http://cropscipublisher.com/index.php/lgg 307 are also useful. Natural hormone analogs such as brassinolide (BR) can improve the photosynthetic efficiency and antioxidant capacity of crops and maintain a high metabolic level under low light and disease stress. Studies have found that BR treatment can reduce the inhibitory effect of low light on nitrogen fixation of leguminous crop nodules, increase leaf chlorophyll content and net photosynthetic rate, and thus alleviate the growth restriction caused by low light. Therefore, spraying low-concentration brassinolide before continuous rain can enhance the ability of pea plants to tolerate rain (Chen et al., 2024). Using fruit-setting regulators to prevent flower and pod drop is also one of the ideas. For example, anti-drop agents (to prevent abscission layer formation) have been used to increase cotton boll formation. They can also be sprayed as appropriate during the pea flowering period when there is continuous rain to help retain young pods. However, the use of plant growth regulators should be scientific and appropriate, and excessive doses may be counterproductive. In terms of nutrient compensation technology, continuous rain leads to insufficient photosynthetic products of peas and obstructed root absorption, which can be supplemented by foliar fertilization. Spraying foliar fertilizers such as urea and potassium dihydrogen phosphate in the intervals between rainy days can directly provide available nitrogen and phosphorus to the leaves and improve the nutritional level of the plants. Especially when spraying in the early sunny days after rain, high humidity opens the stomata of the leaves, which is conducive to nutrient absorption and has a better effect (McGuiness et al., 2020). After rainy days, the soil is often lacking in oxygen and the root activity is low. Some preparations containing active oxidants (such as calcium peroxide, etc.) can be applied to improve the rhizosphere environment. Microbial agents can also play a role: some rhizosphere growth-promoting bacteria can improve plant resistance to stress. Applying them to pea fields with root irrigation can help restore root function damaged after continuous rain. It is worth mentioning that there are cases of using photosynthetic bacterial fertilizers in greenhouse pea cultivation in Japan and Taiwan, my country, to supplement the soil microecology when light energy is insufficient on cloudy days and improve the photosynthetic efficiency of crops. This type of new nutritional compensation method deserves further research and promotion. The combined use of regulators and nutritional compensation can "escort" the growth of peas during continuous rainy days and play a positive role in improving the pod setting rate. 7 Case Studies 7.1 Adaptation strategies in the pea cultivation base of Qiubei, Yunnan Qiubei County, Yunnan Province is located in the plateau hilly area, with diverse climate and abundant rainfall. The local area is one of the important pea production areas, but continuous rainy and low-sun weather often occurs in spring, which poses a challenge to the pea pod setting rate. Taking the spring of 2022 as an example, the Qiubei pea planting base experienced 20 consecutive days of rainy weather in March, during which the sunshine hours decreased by more than 40% compared with the same period of previous years, and the peas generally grew weakly. In response to this continuous rainy process, the base took a series of response measures in time and successfully minimized the losses. First, before the continuous rain came, the technicians checked and cleared the field drainage ditches and reinforced the pea supports to prevent the plants from lodging due to excessive soil moisture. During the continuous rainy process, the base seized the short break and applied foliar fertilizer (0.5% urea + 0.3% potassium dihydrogen phosphate) once in mid-March to supplement nutrients for the plants. At the same time, a broad-spectrum fungicide was sprayed every 7 days to protect the pea inflorescence from gray mold infection. Since mechanical operations were not possible in the field, the base organized manual topping and thinning of the plots with severe canopy to improve ventilation. After these efforts, the pea pod setting rate of the base remained at around 70%, which was slightly lower than that in normal years (about 80% or more), but much higher than the 40% pod setting rate of nearby farmers' plots that did not take measures. Breeding rain-resistant varieties is also one of the key factors. The "Yunwan No. 7" variety mainly planted in the base is more resistant to moisture, has a shorter flowering period, and is highly resistant to gray mold. It showed good pod setting stability during this continuous rain (Semenova et al., 2025). The base also summarized the long-term strategy for developing pea production in Qiubei to cope with continuous rain: including improving soil to increase water permeability, promoting high-bed cultivation, and promoting small arch sheds for rain-sheltered seedlings. These experiences provide valuable reference for pea production in rainy mountainous areas.
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