THE EFFECT OF DROUGHT ON THE WATER REGIME IN THE LEAVES OF SOYBEAN SAMPLES

The research work was aimed at determining the characteristics of the parameters of the water regime and the content of free proline in soybean samples in drought conditions. The seeds of soybean varietal crops used in the study were provided by the Genbank of the Institute of Genetic Resources and grown at the experimental field site of the Institute. The parameters of the water regime in plant leaves were determined under conditions of irrigation and drought. Based on the results of the water-holding capacity obtained on control plants, the content of free proline in the leaves of the experimental varieties Chu-4, Chu-12 and Antonia was determined. Changes in the values of deficiency and relative water content, water retention capacity, and free proline content were observed. Under conditions of water stress, a low level of water deficiency, but a high relative water content was noted in samples of varieties Chu-3, Chu-7, Canada-4, Canada-6, Antonia, Angelica. According to the values of the water-holding capacity, it is possible to judge whether plants withstand drought. In control plants, the water- holding capacity varied in the range of 27.3% (Chu-3) - 50.6% (Antonia), in drought conditions - 33.34% (Chu-12) - 64.93% (Chu-3). Samples with water holding capacity values above 50% in drought conditions can be considered resistant: Chu-3, Canada-1, Canada-7, Antonia, Angelika. Despite the somewhat low value of water-holding capacity, the Chu-7 sample also distinguished itself by drought resistance. There is a certain relationship between the content of free proline and the water retention capacity of the leaves (by water loss within 4 hours), the relative water content and water deficiency. Thus, high indicators as free proline content and relative water content are accompanied by low values of water retention capacity and water deficiency, which indicates water retention in tissues