Study of net photosynthetic productivity, nitrogenase activity and field germination for different soybean genotypes and their correlations with the main vegetacinon indices

The article presents part of the experience in the study of soybean breeding material in the fields of the Federal State Budgetary Scientific Institution «Federal Scientific Center of Legumes and Groat Crops». The studies were conducted in years characterized by contrasting (different) weather conditions, and the varieties and breeding numbers presented in the study differed among themselves in the traits of growth type, precocity and branching. The traits such as net photosynthetic productivity and nitrogenase activity investigated in the bean formation phase were depicted. The cultivars with the highest net photosynthetic productivity at the bean formation phase in 2022 and 2023 were identified, and breeding numbers with low net photosynthetic productivity were noted. Nitrogenase activity of the studied cultivars in the phase of bean formation in 2022 and 2023 was determined. Variety samples possessing the highest nitrogenase activity were identified, as well as selection numbers with low values of this indicator. Soybean genotypes with minimal annual variation of nitrogenase activity in the phase of bean formation were found, which can be used for further selection in the future. Correlations between net photosynthetic productivity, nitrogenase activity, field germination and vegetation indices (NDVI, NDRE, ClGreen, GNDVI, MCARI) were calculated, and the phase of soybean development at which vegetation indices are most optimally applicable for germination assessment was determined.