Response of leaf morphology and photosynthetic characteristics to shading in wild and cultivated soybeans.

The selection of shade-tolerant and high-light-efficient soybean varieties is one of the important research elements of the maize-soybean ribbon complex cropping model. By analyzing the differences in leaf morphology and photosynthetic physiological responses between wild and cultivated soybean seedlings under normal and shaded conditions, we can reveal their shade-tolerance mechanisms and response differences, which can provide a theoretical basis for the breeding of new shade-tolerant and high-light-efficient soybean varieties. In this study, two types of cultivated soybean (Nandou 12 and Tianlong No.1) and two types of wild soybean (W1 and W2) were used as experimental materials to investigate their response to shade under two light environments: natural light and 50% shade. The results showed that the specific leaf weight, leaf thickness, fenestrated tissue thickness, net photo-synthetic rate, stomatal conductance, and photosynthetic pigment content of wild and cultivated soybean were significantly lower under shade stress than under natural light. In shade, cultivated soybean showed higher variation in net photosynthetic rate, photosynthetic pigment content, spongy tissue thickness, and leaf area than wild soybean, while specific leaf weight and ratio of fenestrated tissue to spongy tissue were significantly lower than wild soybean. Wild soybean can improve its adaptation to low light conditions by maintaining Chlb content, increasing the proportion of chlorophyll in photosynthetic pigments and stimulating potential maximum photosynthetic activity as a response. The differences in the response of wild and cultivated soybean to shade conditions could provide theoretical support for future breeding of shade-tolerant soybean. [ABSTRACT FROM AUTHOR]