Effect of salinity stress on growth characteristics of selected almond (Prunus dulcis) genotypes

Almond (Prunus dulcis) is one of the most important crops consumed as dry fruit and mainly adaptable to arid and semiarid regions mostly suffering from salinity stress (8).use of rootstocks and cultivars tolerance to salinity as one of the influence factors tolerance to salinity of planted fruit trees including almond (8 and 11). Temperate fruit trees are generally rated and sensitive to soluble salts and particularly sensitive to chloride, and irrigation with saline water may significantly reduce their yields (10 and 26). Also, most of the stone fruit trees and almond are sensitive to salt stresses and their productivity gradually reduces at salt concentrations above 1.5 ds/m and down to 50% of normal yield at the salt concentration of 4 ds/m (6 and 16). However, as plant species and different cultivars within the same plant species vary considerably in their tolerance to salinity (10), selecting plants and/or cultivars that can be grown well under adverse conditions, created in the root zone by salinization, is the most efficient and environmentally friendly agricultural practice for a more permanent solving of the problem of salinity (10). Despite the presence of information on the effect of salinity on morphological, physiological and concentration of nutrition elements in almond genotypes leaves, should be investigated more rootstocks and cultivars for tolerance to salinity, finality, the most tolerant rootstocks and cultivars to salinity to be introduced. Therefore, the aim of the present study was to evaluate the effects of NaCl stress on growth characteristics and concentration of nutrition elements in selected almond genotypes leaves introducing most tolerant genotypes to it. To evaluate the effect of salinity stress on morphological and physiological traits as well as concentration of nutrition elements of almond leaves, an experiment was carried out based on completely randomized design (CRD), with two factors; genotype and irrigation water salinity with three replications. Studied Genotypes were Rabie, Perless, Super Nova, D99, 1-16 and 8-24 and irrigation water salinity were 0.5, 1.5, 3, 4.5 and 6 ds/m, respectively). Morphological traits such branch height, branch diameter, number of total leaves, percentage of green leaves, percentage of necrotic leaves, percentage of downfall leaves, aerial organs fresh and dry weight, aerial organs dry weight to aerial organs fresh weight ratio and physiological traits such SPAD, relative humidity content, relative ionic percentage, minimum fluorescence (FO), maximum fluorescence (Fm), variable fluorescence (Fv) and Fv to Fm ratio and nutrition elements such as K+, Na+ and Na+ to K+ ratio, was investigated in selected almond genotypes leaves then perform salinity stress. The results showed that type of genotype and level of salinity were affected on growth characteristics and concentration of leaves element nutrient. In all of the studied genotypes, with increasing levels of salinity, branch height, branch diameter, number of total leaves, green leaves percentage, aerial organs fresh and dry weight, relative humidity percentage, SPAD, maximum fluorescence (Fm), variable fluorescence (Fv) and K+ percentage were reduced. But, necrotic leaves percentage, downfall leaves percentage, aerial organs dry weight to aerial organs fresh weight ratio, relative ionic percentage Na+ percentage, Na+ to K+ ratio, minimum fluorescence (FO), and Fv to Fm ratio were increased. Overall, The results showed that type of genotype were effective in tolerance to salinity. D99 cultivar was recognized as the most tolerant cultivar to salinity stress. This cultivar could with keeping growth traits and the more absorption K+ against Na+ was tolerated salinity 4.5 ds/m