Document Type : Research Paper
Authors
Abstract
Despite the high resistance of black saxual (Haloxylon aphyllum) to environmental stress such as drought, there is the possibility of further resistance in different populations. This experiment was carried out to determine the drought tolerance in seven populations of black saxual(Yazd, Esfahan, Semnan, South Khorasan, Sistan va Blochestan, Kerman) under three moisture treatments (100%, 50% and 25% of field capacity) using small weighing lysimeters. The study was conducted in Yazd Shahid Sadoqi Research Station during 2010-2012 using a randomized complete block design with three replications. The effects of soil moisture treatments were studied on morphological traits such as shoot dry weight, root dry weight, root to shoot ratio and physiological traits such as leaf and root osmotic potential, relative water content, water use efficiency, total chlorophyll, chlorophyll a, chlorophyll b, Na+ and K+ accumulation in roots and shoots. According to the results, no significant differences were recorded among the populations in response to the moisture treatments except chlorophyll content (P<0.05). The effect of moisture treatments on water use efficiency and physiological traits such as leaf osmotic potential, relative water content of leaves, total chlorophyll, chlorophyll a, chlorophyll b and Na+ in the root were significant (P<0.01). In addition, the effect of moisture treatments on leaf potassium was significant (P<0.05). Drought stress had no significant effect on other traits, including root osmotic potential, leaf Na+ and root K+. Effects of drought stress on morphological traits including shoot dry weight, root dry weight, total dry weight, and root to shoot ratio were significant (P<0.001). The interaction effects of population and moisture treatments on morphological characteristics were not significant.
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