The aim of the research is to study the variability of protein and fat content in soybean seeds of early cultivar ‘VNIIOZ 76’, very early cultivar ‘VNIIOZ 86’, and mid-early cultivar ‘Volgogradka 1’. The research was fulfilled on the materials of field experiment conducted in 2007-2012 at the irrigated lands of the dry steppe zone of light-chestnut soils in the Volgograd region. The variability of protein and fat content in soybean seeds was studied assessing the impact of such factors as cultivar, seeding technique, and conditions of water and nutrient supply. The primary impact had a cultivar factor (factor proportion of the total variance – 60.0 % for protein and 71.5 % for fat) and the factor of water supply conditions (factor proportion of the total variance – 14.3 % for protein and 28.9 % for fat). Protein content increases proportionately to the increase of nutrient supply (Pearson correlation – 0.29) and declines while the threshold of pre-irrigation soil moisture elevating (Pearson correlation – 0.38). The most stable quality of soybean seeds in the climate conditions of Lower Volga were under applying the dose of mineral fertilizers less N95P160K150 and maintaining pre-irrigation threshold at flowering and bean forming phases higher than 80 % FC. Variation coefficient for protein and fat content doesn’t exceed 2.0-3.2 %. The conditions mentioned above enable to get seeds of the cultivars ‘Volgogradka 1’ and ‘VNIIOZ 86’ with protein content up to 37.1 %. The same combination of factors for cultivar ‘VNIIOZ 76’ provides fat content about 24.8 %, what is thoroughly sufficient for the requirements of fats and oils production industry.
Keywords: soybean, grain quality, protein, fat, components of variance, correlations, variability, factor analysis.
