DYNAMICS OF RELATIVE CONTENT OF PHOTOSYNTHETIC PIGMENTS IN LEAVES OF PLANTS OF NEW SOYBEAN VARIETIES UNDER CULTIVATION IN THE CENTRAL BLACK EARTH REGION OF THE RUSSIAN FEDERATION

The quantitative content and qualitative composition of pigments, changes in their ratio in assimilatory organs are important and sensitive indicators of physiological processes that characterize plant homeostasis. Temperature regime and precipitation are among the main environmental factors influencing the state of the pigment complex, as well as the rate of carbon deposition and biocenosis productivity. The mechanisms of transformation at the level of primary photosynthetic reactions of energy conversion in soybean plants depending on temperature and moisture availability are insufficiently studied. In 2020-2022, soybean varieties Leader 1, L-10, L- 171 of the FSC LGC breeding and Canadian varieties Amadeus, Asuka, Nordica were studied in a field experiment. The content of chlorophylls and carotenoids in leaves was determined in the phase of flowering and bean filling. Under favorable conditions (high water availability and temperature), the photosynthetic apparatus of new soybean varieties shows high physiological activity, forming the maximum amount of Chla+b in leaves. In wet years with values of hydrothermal coefficient (HTC) = 2.1-2.3, the amount of the sum of chlorophylls and carotenoids is higher than in drier years with HTC = 1.4 by 83% and 38%, respectively. An increase in pigment content at low insolation promotes the efficient use of light energy, which is a manifestation of the adaptation of soybean plants to abiotic factors. A change in the ratio of pigments indicates compensatory mechanisms aimed at stabilizing the photosynthetic activity of plants. The photosynthetic apparatus of soybeans remains highly efficient during the bean filling period, which is confirmed by a significant (up to 10.6 mg/g dry matter) concentration of the total chlorophylls. Varietal differences in accumulation of photosynthetic pigments were revealed: according to 3-year data, the highest amount of green pigments was observed in the flowering phase in the Amadeus variety: Chla - 6.4 mg/g dry matter, Chlb - 5.3 mg/g dry matter, carotenoids - in the L-10 line 2.0 mg/g dry matter. Foreign breeding varieties surpass domestic varieties in Chla+b content by an average of 17%. Thus, the transformation of pigment complex depending on weather conditions allows soybean plants to maintain photosynthesis at the optimal level