The aim of the present study is to determine the impact of the disturbed irrigation regime on the yield and the chemical composition of Sudan grass, grown as a second crop. To accomplish this goal, a trial was conducted in the experimental field of the Agricultural Institute – Stara Zagora with Sudan grass on meadow-cinnamon soil under irrigated conditions. The following variants have been studied: 1 – without irrigation (control variant); variant 2 – optimal irrigation, 75-80% of field capacity (FC); variant 3 – irrigation as in variant 2, but with the removal of the first watering; variant 4 – irrigation as variant 2, but with the removal of the second irrigation; variant 5 – irrigation as variant 2, but with the removal of the third watering. It was found that when growing Sudan grass as a second crop with optimal irrigation and disturbed irrigation regime done by canceling successive watering, the highest yield of dry biomass is obtained with optimal irrigation including three irrigations. Its yield increased by 24.2% compared to the control treatment. Irrigation of Sudan grass with only the second and the third irrigation in a row, without the first irrigation provided, leads to the lowest yield of dry biomass – 11290 kg / ha. Among the chemical composition indicators, the most significant change is observed in the content of the crude fat, followed by that of the crude fiber and crude protein, depending on the method of growing Sudan grass (with or without irrigation).
Keywords: Sudan grass, irrigation regime, yield, chemical composition