INFLUENCE OF HYDROTHERMAL CONDITIONS OF VEGETATION ON DRY MATTER ACCUMULATION BY BUCKWHEAT PLANTS IN THE MIDDLE VOLGA REGION

The studies were conducted in 2018-2023 in the Republic of Tatarstan to determine the patterns of synthetic processes in buckwheat genotypes created on the basis of fasciated forms (K-990) and Batyr variety, during critical periods of crop formation (flowering and fruiting) under conditions of varying hydrothermal availability, to identify promising breeding material. The soil of the experimental plot was grey forest medium loamy with a humus content (according to Tyurin) of 3.2…4.4%, potassium and phosphorus (according to Kirsanov) of 110…123 and 145…377 mg/kg, respectively, and a salt extract pH of 5.3…6.6. The dry biomass of plant organs was assessed during the flowering and fruiting phases. The data set was divided by year into two blocks: dry (hydrothermal coefficient (HTC) of the flowering and fruiting periods≤0.8) and favorable (HTC≥0.9). In the flowering phase, the stem biomass of the fasciated genotype was 36% less than that of Batyr variety, and in the fruiting phase, it was 31.6% higher, mainly due to the thickening and development of the stem, rather than its length. In dry years, the increase in the mass of fruit elements from the flowering phase to the fruit formation phase in the fasciated genotype was 2 times greater than in Batyr variety. In favorable conditions, the opposite situation developed: in Batyr variety, the increase was 1.5 times higher than in K-990. A close correlation was noted between the accumulation of dry biomass of fruit elements with the average daily air temperature in the budding phase (r =+0.75) and with the amount of precipitation in the fruit formation phase (in K-990, r =+0.98, in Batyr, r =+0.94). The features of biosynthesis in the organs of the fasciated form of K-990 in years with different hydrothermal conditions indicate its thermophilicity and drought resistance.