Response of Bulgarian and Indian Soybean Genotypes to Drought and Water Deficiency in Field and Laboratory Conditions

Drought is one of the limiting factors for better plant performance and higher yield. New variety selection is difficult due to the complex mechanism of drought resistance. Four Bulgarian soybean lines (selected after hybridization and mutagenesis), two Indian and one USA variety were used for field and laboratory experiments. Drought tolerance was estimated in irrigated and non-irrigated conditions. Bulgarian lines (compared to the world standard cv Hodson) had higher productivity by 17-44 kg/da in drought conditions. In laboratory experiments water deficiency was simulated by polyethyleneglycol (PEG) of MW 6000 in the following concentrations viz., 2, 4, 6, 8, 10 and 15 % (w/v) for seed germination. A linear and significant reduction in germination, shoot and root length, and their corresponding fresh and dry weight was observed for the genotypes as the concentration of PEG increased. The level of the negative effect of the osmoticum on developmental processes was genotype dependent with less damages for three Bulgarian lines, and especially for Line 5, which had highest seed yield under stress 240 Kosturkova et al.