Effect of Salinity Stress on Some Growth Indices, Proline, Aldehydes and Soluble Sugars in Six Iranian Commercial Pomegranate Genotypes

In order to investigate the effect of salinity stress on the morphological and physiological characteristics of some Iranian commercial pomegranate cultivars and possible identification of salinity tolerant cultivar, a greenhouse experiment conducted in Agricultural College of Lorestan University in 2015. The experiment carried out as factorial based on randomized complete blocks design with five salinity levels and three replicates. The levels of salinity based on urban water was include 0, 25, 50, 75 and 100 mM sodium chloride (with EC equal to 0.66, 3.35, 6.21, 9.72 and 14.35 dS/m, respectively), and six pomegranate cultivars including Malas Dane Ghermez Esfahan, Malas Yazdi, Shirin Shahvar, Meykhosh Yazd, Malas Saveh and Malas Yousofkhani. After three months of salt stress, some morphological, physiological and biochemical characteristics of the plants were examined and measured. The results of this study showed that with increasing salinity, plant height, leaf size, the fresh and dry weight of leaf and root, and chlorophyll content of plants decreased, but leaf necrosis rate, the concentration of proline, malondialdehyde, other aldehydes, and soluble sugars increased. The research findings showed that in salinity conditions up to electrical conductivity of 6.21 dS/m, all cultivars showed acceptable tolerance to salinity. In higher salinity, Malas Saveh cultivar had superiority in salinity tolerance traits, including lower decrease in plant height, leaf fresh and dry weight, and chlorophyll and malondialdehyde concentrations along with lower leaf necrosis and therefore, for the traits evaluated in this experiment, than other cultivars had higher salinity tolerance.