Relationship of Inductional Changes in the Fluorescent Indices of Soybean (Glycine max (L.) Merr.) Leaves with their Biochemical Characteristics and Productivity

The impact of growth conditions on the fluorescent characteristics of the leaves of the vegetable and cultivated oilseed forms of soybean (Glycine max (L.) Merr.), which were introduced in central Russia for the first time, was studied. The following parameters of fluorescence induction were used: NPQ (nonphotochemical fluorescence quenching), qP (photochemical fluorescence quenching), Qy (actual quantum yield of photochemical reactions in photosystem II), Qymax (maximum quantum efficiency of photosystem II), and Rfd (vitality coefficient). Using soybean plants in the flowering and technical ripeness phases as an example a direct relationship between nonphotochemical quenching and the Rfd indicator (r = 0.95), as well as an inverse relationship between the Fv indicator with photochemical quenching (r = –0.89 and r = –0.78 in the flowering and technical ripeness phases, respectively) was shown. The biochemical parameters were studied and their correlation with the photosynthetic parameters of the leaves of vegetable forms of soybean was analyzed. As an example, the accumulation of antioxidants had approximately the same moderate degree of correlation (r = 0.40) with Qymax, Rfd, and qRstat. At the end of the growing season, the correlation of the vitality coefficient in the technical ripeness phase with the productivity of vegetable soybean in the phase of full biological ripeness, namely, the weight of the plant (including the underground part), the number of beans per plant, and the weight of seeds per plant, were analyzed. There was a stable positive correlation between these indicators from r = 0.78 (with the mass of the plant and the mass of seeds from the plant) to 0.90 (with the number of beans per plant). The vitality coefficient has practical significance, playing the role of a quantitative characteristic of plant productivity, which makes it possible to use PAM fluorimetry in the assessment of the physiological state of a plant organism and its economic efficiency. © 2021, Pleiades Publishing, Inc.