Influence of Sowing Periods and Seeding Rates on Yield of Grain Sorghum Hybrids under Regional Climatic Transformations

Abstract

Field experiments were carried out on dark chestnut middle loamy slightly alkalinized soils in the non-irrigated conditions of the southern steppe of Ukraine in 2013-2015. The three-factor experiment: Factor A-grain sorghum hybrids: Sontsedar, Prime, Burggo, Sprint W, Dash E and Targga. Factor B-seeding rate, thousand pcs/ha: 100, 140, 180 and 220. Factor C-sowing time: early (when soil temperature at the depth of seeding is 8-10 C), which on average during the years of research coincided in time with the first decade of May; late-when soil temperature is 14-16 C or the third decade of May. In all cases, the early sowing show persistently higher yield of hybrid crops compared to late sowing. The early term of sowing grain sorghum hybrids provided average yield of certified seeds at 4,9 t/ha, which is 1.82 times higher than late sowing, the average yield of which was 2.69 t/ha. Significant variation in yield was observed with different seeding rates. The highest average yield was observed at the sowing rate 140 thousand pcs/ha followed by 180 and 220 thousand pcs/ha .