DROUGHT EFFECTS ON PHYSIOLOGICAL PARAMETERS OF DURUM AND BREAD WHEAT

The present research discusses the dynamics of changes in the surface of assimilation organs of different durum and bread wheat genotypes differing in the maturation period due to drought conditions. Under drought conditions, the soil water potential decreases, and in the later stages of the plants, the turgor pressure decreases, the stomata close, and a sharp decrease in photosynthetic activities. The situation creates stress in the crop plant, and various biochemical, physiological, and molecular reactions arise to overcome and protect itself from stress, allowing the plant to develop resistant mechanisms to adapt to the external environment. The existent research aimed to determine drought effects on assimilating surface areas and productivity traits of durum and bread wheat genotypes differing in their maturation periods grown under various climatic and soil conditions, with the comparison of the physiological indices. The experiments proceeded on wheat genotypes with contrasting maturation periods (early, medium, and late) during 2021-2022 at the Research Institute of Crop Husbandry, Absheron, Azerbaijan. The assimilating surface area of various organs underwent comparative studies in two durum (Garagylchyg-2 and Alinja-84) and two bread wheat (Nurlu-99 and Gobustan) cultivars under normal water supply and drought conditions. Post anthesis water stress caused a 34% and 27% reduction in grain yield and 1000-grain weight, respectively, while no significant effect on the grains per spike and spikes per m2. The averages of grain yield and 1000grain weight of different wheat cultivars in the controlled condition showed 696 +/- 36 g/m2 and 43.1 +/- 0.8 g/m2, respectively, while under water-stress conditions, these values significantly decreased to 452 +/- 57 g/m2 and 31.6 +/- 1.4 g. The significant reduction in grain yield due to post-anthesis water stress might be due to a reduction in photo-assimilates production.