Analysis of photosynthetic characteristics of Glycine max (L.) Merr and screening of high-efficiency germplasms

Photosynthetic efficiency represents a primary physiological determinant of yield and quality in soybean (Glycine max (L.) Merr.), serving as the fundamental driving force behind growth and production. To elucidate the relationships between photosynthetic characteristics, yield, and quality, a comprehensive analysis was conducted on 52 soybean germplasms, encompassing photosynthetic gas exchange parameters, chlorophyll content, chlorophyll fluorescence indices, and yield- and quality-related traits. A multidimensional evaluation model of photosynthetic efficiency was established, and key photosynthetic parameters influencing performance were identified. Results indicated that net photosynthetic rate (P_n), stomatal conductance (G_s), relative chlorophyll content (SPAD), and relative electron transport rate (ETR) were critical indicators for assessing photosynthetic efficiency. Linear regression analysis indicated that SPAD, initial fluorescence (F₀), and leaf instantaneous water use efficiency (WUE) significantly impacted yield, while actual quantum yield of PSⅡ (Y(Ⅱ)), P_n, and intercellular CO₂ concentration (C_i) had significant effects on fat accumulation. C_i and transpiration rate (T_r) primarily affected protein synthesis. These findings provide a scientific basis for germplasm screening and breeding of high light-efficiency soybean cultivars, supporting sustainable agricultural development and enhancing competitiveness of the soybean industry.