Wheat genotypes respond differently under polyethylene glycol (PEG) induced drought stress during germination and early seedling growth stages

Abstract

Water scarcity has emerged as one of a critical environmental constriction that negatively affect wheat growth, development and yield in Bangladesh. Identification of drought tolerant genotypes is crucial at drought sensitive initial stages of plant growth especially germination and seedling growth stages. To cater this issue, 30 wheat genotypes were subjected to polyehelene glycol (PEG 6000) induced drought stress levels of 0,-2.0 and-4.0 Mpa (osmotic stresses) and their response was tested at the germination and seedling growth stages. The experimental set up was Completely Ramdomized Design (CRD) with five replications. The results revealed that the rate of germination (RG) among the genotypes varied significantly with the different water potential levels, and the RG decreased with the advancement of stress. The stress tolerance index (STI) values based on RG were > 0.900 in wheat cultivars of Shatabdi, BARI Gom 25, BAW 1118, BAW 1151, BAW 1161, E 2, E 18, E 30, E 34 and E 38under severe water deficit stress, while the values were < 0.800 in wheat genotypes BARI Gom 26, BARI Gom 27, BARI Gom 28, BAW 1130, BAW 1140, BAW 1143, BAW 1168, E 28 and E 42. The co-efficient of germination (COG) was significantly decreased with increasing water potential stresses (-2 &-4 bars), and the genotypes Sourav, BARI Gom 25, BAW 1118, BAW 1135, BAW 1151, BAW 1157, BAW 1161, BAW 1163, BAW 1170, BAW 1171, E 2, E 18, E 23, E 29, E 34 and E 38showed > 0.980 STI values whereas, BARI Gom 26, BARI Gom 27, E 24, E 28, E 42, BAW 1130, BAW 1140 and BAW 1168 produced < 0.970 STI values under higher water potential. Higher STI values (> 0.920) regarding the germination vigour index (GVI) under higher water stress were observed in BARI Gom 25, E 18, E 23, E 34, E 38, BAW 1118, BAW 1161 and BAW 1170, and very lower STI values (< 0.800) were obtained in the Shatabdi, BARI Gom 26, BARI Gom 27, BAW 1130, BAW 1140, BAW 1168, E 3, E 24, E 28 and E 42 genotypes. The genotypes Shatabdi, BARI Gom 25, E 18, E 38, BAW 1118, BARI Gom 27, E 24, E 34, BAW 1143 and BAW 1170 showed higher STI values (> 0.550) indicating tolerant genotypes and the genotypes Sourav, BARI Gom 26, BARI Gom 28, BAW 1130, BAW 1151, BAW 1168, E 2, E 3, E 28 and E 29demonstrated lower STI values (< 0.450) designating susceptible genotypes. As water deficit stress increased, the shoot weight (g) of wheat genotypes decreased. Notably, genotypes Shatabdi, BARI Gom 25, E 18, E 34, E 38, and BAW 1118 exhibited Stress Tolerance Index (STI) values greater than 0.700. In contrast, genotypes BARI Gom 26, E 2, E 23, E 29, BAW 1130, BAW 1140, BAW 1151, BAW 1157, and BAW 1161 displayed STI values lower than 0.550. The genotypes showing higher and lower STI values denoted water stress tolerant and susceptible genotypes, respectively.