Effects of salinity and drought stress on germination and seedling Datura innoxia Mill.

Seed germination is first critical and the most sensitive step in the life cycle of plants. In order to study the effects of environmental factors on germination characteristics Datura innoxia, four completely randomized design with 6 replication were conducted at Agricultural Research Bahar University, Hamedan, Iran. Salinity stress was induced by using sodium chloride (NaCl) and drought stress by using Polyethylene Glycol (PEG-6000). Five ml NaCl solution and PEG6000 (-0.2, -0.4, -0.6, -0.8, -1 MPa) were added in different petri plates. To study the effect of pH on germination, pH solutions with acidity of 4 to 9, and depth effect on seeds cultivated at depths of 0, 2, 4, 6, 8 and 10 cm. Analysis of variance of the effects of salinity and drought stress on seed germination of D. innoxia suggested that these treatments made significant changes at (P<0.05). The reduction in seed germination was proportional to the increasing concentration of NaCl and PEG. With the increasing intensity of drought and salinity from 0 to -1 MPa D. innoxia germination percentage of 100 percent respectively compared to control was reduced. Fitting of three-parameter logistic model, showed that salinity and drought stress at - 0.39 and –0.27 MPa, respectively caused 50% reduction in maximum germination percentage of D. innoxia. In addition 50% decrease in germination speed caused by salinity and drought stress, were observed in -0.33 and -0.28 MPa, respectively. The optimum pH for germination was 7 and the pH increased by decreasing the germination percentage. The highest percentage of emergence of in surface soil seeds was 73.33% and with increasing soil depth the percentage of seedling emergence decreased. Only 3% of the seeds are able to germinate from a depth of 8 cm.