PEG-induced drought stress effects on soybean germination parameters

As a result of global climatic changes, water deficiency is threatening food production for the increasing population worldwide, especially drought-sensitive crops, to which soybean belongs, by suppressing yield potentials. Drought stress can inhibit sown seeds' germination and manipulate germination parameters. A controlled, two-stage experiment was conducted to investigate the effects of drought stress, induced by PEG (polyethylene glycol), on some germination parameters of two soybean cultivars; 'ES Mentor' and 'Pedro', in Debrecen, Hungary in 2018. At the first stage, 5 PEG concentrations; 10, 15, 20, 25, and 30%, besides control (0% PEG), were applied to each cultivar in 3 replicates. Results showed that both cultivars could not germinate when 25 and 30% of PEG were applied. Significant differences among PEG concentrations, between cultivars and their interaction were recorded. Based on these results, the second stage consisted of 6 PEG concentrations; 2.5, 5, 7.5, 10, 12.5 and 15% (besides control), also in three replicates. For both cultivars, germination ratio (GR) and root elongation (RE) decreased as the PEG concentration increased. Both germination energy (GE) and ultimate germination (UG) decreased, whereas mean period of altimate germination (MPUG) and percentage inhibition increased with increasing water stress. 'ES Mentor' could maintain higher (GR) than 'Pedro' under all PEG concentrations except 15%, whereas (RE) was lower under all concentrations. It was concluded that 'ES Mentor' can germinate better under different water deficiency levels; however, germinated seeds of 'Pedro' can tolerate relative water stress better, as the roots could elongate deeper searching for available water.