Influence of sowing time on the modern grain sorgo hybrids adaptive capacity in Donbass

The purpose of the study is to establish the optimal sowing time for grain sorghum, which ensures the maximum adaptation of modern hybrids, the annual consistently high yield in the Donbass. Field experiments were carried out in 2008-2017 on the basis of the experimental field of the Luhansk State Agrarian University. The objects of study are the early-ripening hybrid of grain sorghum Dash E and the mid-early hybrid Sprint W. Six sowing dates were studied: April 25, May 5, May 15, May 25, June 5 and June 15. Analysis of variance was used for evaluation; coefficients of ecological plasticity (bi), stability (S2d) and yield variation (CV); general adaptive capacity of the genotype (GCA); drought resistance (IR), intensity (II) and stability (SI) indices; indicators of stress resistance, genetic flexibility, variety stability level (Puss). The index of conditions of the year had the greatest impact on the harvest (53.8-47.3 %), and the sowing time had a slightly smaller effect (35.2-38.8 %). Over 10 years of experiment, the maximum yield of the Dash E hybrid was obtained at I and II sowing terms, with reduced plasticity (bii2 = 0.397-0.245) and the highest stress resistance (-3.41…-3 .81 t/ha), drought resistance index (56.6-51.3 %), genetic flexibility (6.16-5.92 t/ha), general adaptive capacity (0.98-0.84 t/ha), stability index (0.30-0.28) and variety stability level (176.4-160.7 %). The hybrid Sprint W provided the maximum yield and adaptation parameters at the first sowing term (plasticity (bi ≈ 1.0), stability (Si2 = 0.667), genetic flexibility (6.58 t/ha), general adaptive capacity (1.25 t/ha). ha), stability level (169.6 %)).