The influence of moisture conditions on the yield of grain sorghum and millet in Donbass

In the steppe arid conditions of Donbass, millet and sorghum are the most thermophilic, drought-, heat-resistant, productive and adapted to the stress factors of weather conditions. The purpose of the research is to study the influence of various conditions of moisture supply during the growing season on the yield of millet and grain sorghum when sown within acceptable time limits (25.04; 15.05; 5.06). The research was conducted at the experimental field of the Lugansk State Agrarian University in 2015-2018. At the studied sowing dates, the pre-sowing reserves of productive moisture in the meter-long soil layer had no correlation with sorghum yield. During the period "shoots - full ripeness", the largest amount of precipitation (182.4 mm) fell on sorghum crops at the first sowing date (April 25), which exceeded their number by 24.1 % at the second (May 15) and by 21.4 % at the third (May 5) sowing dates. During the "flowering - full ripeness" period, sorghum plants of the first sowing period were also provided with a larger amount of precipitation (on average 60.0 mm), compared with later periods with later sowing dates. Due to this, at the first sowing period, the Selyaninov hydrothermal coefficient (GTK) was 0.76, at the second - 0.64, at the third - 0.63. For the early (April 25) sowing period of millet, a strong correlation (r = 0.92) was noted during the "tillering-flowering" period, and for later sowing periods (May 15 and June 5) - during the "flowering-full ripeness" period (r = 0.89-0.90). When sowing millet on April 25, the most favorable conditions of moisture supply were noted. At the same time, during the periods "shoots - full ripeness" and "flowering - full ripeness", precipitation totals were 182.9 mm and 103.0 mm, respectively. This provided a high correlation between yield and precipitation over the entire growing season (r = 0.77).