Effect of drought stress induced by polyethylene glycol (PEG-6000) on seed germinating traits of seven provenances of wild almond (Amygdalus scoparia Spach.) in the Fars Province, Iran

Wild almond (Amygdalus scoparia Spach.) is a drought resistant species with a wide spatial distribution that is extensively used in arid and semi-arid afforestation plans of Iran. Increasing the success of rehabilitation of deforested areas and classification of germplasms entail employing seed resources with good germination rate. To investigate the effect of drought stress on seed germination traits of wild almond populations in Fars province, a factorial experiment was conducted in a completely randomized statistical design. Almond populations were tested on 7 levels (Marvdasht, Pasargard, Arsanjan, Fasa, Kavar, Darab and Khonj), and osmotic stress of polyethylene glycol was studied in 4 levels (0, -0.05, -0.1 and -0.5 MPa). Results of analysis of variance (ANOVA) showed that the main effects of water stress, population and their interactions were significant on all indicators of germination at p ≤ 0.01. In addition, a diverse sensitivity of populations was observed to levels of drought stress. Increasing the water potential in the germination media had an adverse effect on most seed germination traits. At the highest drought stress levels, the average germination time in populations located in northern Fars was more than those in the southern populations. The population of Khonj showed the highest germination percentage, coefficient of velocity of germination, germination index, and germination rate index and germination value compared to the other studied populations. Using the seeds of this population is therefore recommended if approved in field trials.