Effect of Drought Stress Induced by Polyethylene Glycol on Seed Germination of Four Wild Almond Species

Effects of drought stress induced by polyethylene glycol (PEG) on germination of four wild almonds were evaluated. The seeds of Prunus scoparia Spach, P. eleagnifolia Spach, P. lycioides Spach and P. dulcis Mill (No. 24 Zarghan) were collected and stratified at 4±1 °C for 4 weeks. Stratified seeds were incubated in PEG solution with various osmotic potentials (0, -0.05, -0.1 and -0.5 MPa). The experiment was arranged in a completely randomized design with 4 replications, and germination capacity, mean and time of germination, germination rate, length of hypocotyls and radicles and also fresh and dry weight of seedlings were determined. Germination capacity, germination rate and growth parameters of all species were decreased by increase in PEG concentration and germination onset was also delayed. Furthermore the results indicated that osmotic stress depressed the hypocotyls growth more than radicle; and root systems were more drought tolerant. Although PEG adversely affected the germination of all 4 species, they responded differently to drought stress. P. scoparia showing higher germination capacity, germination rate and seedling length had the highest tolerance to drought stress and P. eleagnifolia in early phase of its seedling growth could not completely cope with drought stress. The germination results revealed the presence of drought resistant almonds with rich germplasm in Iran