Comparative assessment of the work of photosystem II in the leaves of soybean varieties and hybrids

The efficiency of PS II of soybean leaves was shown depending on the genotype of the variety, the phase of plant growth and development, and the intensity of their illumination in the field. Purpose of the work: to study the intensity of photosynthetic processes in soybean leaves using a MINI-PAM fluorometer to isolate highly active ones. The object of research was early maturing and mid-maturing varieties, white-flowered soybean hybrids. The efficiency of PS II (Y) with a sequential increase in the illumination intensity was determined in the early ripening variety Sonata and the mid-ripening Oktyabr 70. The most stable efficiency of PS II was in the leaves of the varieties Sonata and Oktyabr 70 at an illumination degree of ≈ 800 to 1500 μmol quanta m-2 s-1. The Sonata cultivar had a higher potential in the restoration of the photochemical activity of PS II. The dependence of PS II activity on the phase of plant growth and development was revealed. A high level of effective quantum yield of PS II (0.84 ... 0.86 rel. units) during the growing season was noted in the leaves of new soybean varieties Kruzhevnitsa, Evgeniya, Persona and Kitrossa. Plants of the white-flowered collection had the maximum parameters of the quantum yield of PS II during the period of formation of reproductive organs. The data obtained allowed us to recommend the varieties Sonata, Kruzhevnitsa, Evgeniya, Persona, and Kitrossa, as well as hybrids KB (5) and KB (26) for inclusion in the breeding process, as they have a high level of PS II work, when creating varieties with increased photosynthetic activity.