Investigation of the physiological features of winter wheat varieties under the action of water stress

Abstract

Regarding the annual production of about 757 million tons (in 2017) (USDA, 2018), bread wheat (Triticum aestivum L.) occupied the first place as a major cereal crop in the world's trade. Winter wheat is not only a world's leading cereal crop but also the most important food crop in Ukraine, which has occupied a leading position in the national agriculture, talking about 48% area under cereals and contributing 38% of the total food grain production. However, obtaining stable and high yields of winter wheat is significantly limited by drought, high temperatures, waterlogging of the soil and other adverse environmental conditions. The subject of the article is the reaction of winter wheat to water-temperature stress. The research was carried out in laboratory and field conditions with five varieties of winter wheat - weakly drought-resistant Poliska 90,Zysk,Bohemia Sotnytsia, and Odesska 66. Soil moisture, the total water content in the leaves of plants were determined by thermal drying. The weight of 1000 grains was determined by weighing on an electronic scale to the nearest 0.1 g. The protein content in the grains was determined by the chloramine method, according to Pochinko. Repetition of biological experiments 3-4 times, analytical - 6-7 times. The research results were statistically processed. Based on the research result, the following conclusions can be drawn: Water supply conditions affected the total water content in the leaves of winter wheat varieties of different ecotypes. With optimal water supply of wheat, the total water content in the plant of different drought resistant varieties of wheat leaves did not differ significantly and was at the level of 81-83%. Water stress caused a significant decrease in leaf water content in the low-drought-resistant variety Poliska 90 compared to other varieties. With optimal water supply, a larger mass of grain yield was formed by the Bohemia, as evidenced by the greater mass of 1000 grains in this variety of wheat compared to the others. Water stress caused a significant decrease in yield in low-drought-resistant variety Poliska 90. The protein content in terms of weight of 1000 grains under the action of water deficit decreased significantly in Sotnytsia variety. The magnitude of water deficit in plant leaves varied according to the level of soil moisture. The decrease in soil moisture was accompanied by an increase in water deficit in the leaves, to a greater extent in the less drought-resistant winter wheat variety Poliska 90. Daytime water deficit in plant leaves was highest at noon, gradually decreasing in the evening. During the period of maximum stress of meteorological factors, the more drought-resistant winter wheat variety Odesska 66 was characterized by more economical use of water for transpiration, which is obviously genetically determined. After water deficiency chlorophyll concentration in leaves of Bohemia decreased more significantly than in other varieties. The length of the roots was related to decreasing the water content. The lower the soil humidity was, the longer roots appeared.