Effect of Drought Stress by Polyethylene Glycol 6000 on Six Wheat (Triticum aestivum L.) Varieties at Germination and Seedling Stages

Six varieties of wheat (Triticum aestivum L.) Al-Mokhtar, Margawi, ACSAD901, Casy, Karim, and Salampoo were evaluated under 5 drought levels 0, 60, 120, 180 and 240 g/L (0.00 (control), -0.066, -0.201, -0.407, -0.682 MPa). To make drought stress conditions we used polyethylene glycol (PEG6000). Germinated seeds were counted daily for up to 14 days under laboratory conditions. Germination percentage and mean germination time, coefficients of germination, mean germination rate, and germination index as germination parameters. Seedling, shoot and root length; fresh, dry weight of shoot and root, seedling vigor index, and reduction percentage as seedling growth parameters were studied. Germination and growth of wheat seedling were affected significantly by changes in water stress levels between -4 and -8 MPa. Margawi variety had the highest germination percentage (78%) among the six varieties, followed by Karim. The two varieties of Salampoo and Casy showed the longest mean germination time. We also noticed that Margawi variety was the fastest at the average germination rate, followed by Al-Mukhtar, Karim, and ACSAD 901. The studied varieties showed a clear decrease in all the germination criteria studied at the high drought rates (-0.407 and -0.682 MPa). By studying growth parameters, the variety al-Mokhtar followed by ACSAD 901 and Margawi higher in shoot length; ACSAD 901, Margawi, and Al-Mokhtar sequentially in plant length.