INFLUENCE OF DROUGHT ON THE QUALITY OF SOYBEAN GRAIN IN THE CONDITIONS OF SOUTH-EAST OF KAZAKHSTAN

Central Asia and Kazakhstan are at risk of drought and are particularly vulnerable to climate change. The main threats are associated with an arid climate and an increase in average annual temperatures. Water scarcity is a key abiotic factor affecting soybean yields. World soybean production is mainly aimed at obtaining vegetable protein and oil. In this regard, the aim of our study was to investigate the effect of drought stress on the protein and oil content of soybean seeds of different maturity groups in order to find genotypes that can minimize protein and oil losses under irrigation deficit in the conditions of southeastern Kazakhstan. In the conditions of southeastern Kazakhstan, 19 soybean genotypes of 5 soybean maturity groups were studied against contrasting backgrounds of irrigation and without irrigation. The studies were carried out over four years (2020-2023). In our studies, we noted that the protein content in the early maturity groups MG 00 (43.8-44.1%) and MG 0 (43.7-44.9%) was significantly higher than that of the MG II - MG III samples (39.3-41.3%), both under irrigation and in the drought experiment. It was found that in the experiment with irrigation deficit, the protein content on average for all maturity groups was significantly higher by 3% than under irrigation, and the oil content decreased by 3.1% compared to the experiment with irrigation. The study of the protein and oil content in soybean grain under drought conditions allowed us to record weak positive correlations between grain yield values and protein (r = 0.12) and oil (r = 0.26) content. Soybean genotypes with high protein (4) and oil (4) content were identified, which did not reduce their values under the influence of drought stress. Selection of drought-resistant genotypes adapted to irrigation deficit, not reducing protein and oil accumulation will minimize crop losses, increase the profitability of soybean cultivation when unfavorable conditions of insufficient irrigation occur.