Effect of drought stress induced by altitude, on four wild almond species

Almond is one of the major shrub species with high ecological extent in Iran. Impact of climate change and drought stress on forest ecosystems، as well as the unsuitable conditions of Zagros forest ecosystem and importance of planting shrub species at such ecosystems، have brought the attentions to use the wild almond species in forest plantation programs. Awareness of the impact of habitat factors on tolerance to environmental stresses will guarantee success of most of the forest rehabilitation programs. For this reason، seeds of four wild almonds، including Amygdalus arabica، A. scoparia، A. haussknechtii and A. eleagnifolia، were collected from three altitude levels، including: 1600-1800، 1800-2000 and more than 2000 m. above sea level at Karebas site; (Chaharmahal and Bakhtiari province)، west of Iran. After cold stratification، the seeds were sown in nylon bags. Two months later، the seedlings were treated by four levels of drought stress (control، -0. 4، -0. 8 and -1. 2 MPa) induced by application of Polyethylene Glycol 6000 in irrigation water، using the factorial experiment under the completely randomized design with three replications (five seedlings per each replicate). Results showed that drought stress significantly reduced seedlings growth characteristics، including total height، shoot height and shoot wet and dry weight، except root wet weight which was increased. Furthermore it increased seedling''s nitrogen and calcium content، while the minimum levels belonged to control treatment. In addition، the seedlings from the lowest (1600-1800 m. a. s. l.) and the highest (above 2000 m a. s. l.) altitude origin، provided the highest and the lowest growth values، respectively. Overall، Amygdalus arabica showed the highest resistance to drought levels among the other species، due to its greatest growth values at these hard circumstances.