SCREENING DATE PALM CULTIVARS FOR SALINITY TOLERANCE USING PHYSIOLOGICAL INDICES

Salinity is a major environmental constraint for plant growth and crop production worldwide. Selection of salt tolerant cultivars of date palm as a fruit crop of high salt tolerance and an extremely important strategic crop in arid and semi-arid regions of the world is quite necessary for the most economical use of salt affected soils in these regions. In present study, five commercial Iranian date palm cultivars were screened for salt tolerance using 10 physiological indices, in a pot experiment under greenhouse condition. Levels of 0, 60, 120, 180, 240 and 300 mM NaCl were hydroponically applied on 1-year old plants derived through tissue culture. Stress tolerance indices related to total fresh and dry weights, root fresh and dry weights, shoot fresh and dry weights, leaf area, collar growth, intact leaf and leaf water content were calculated. The data were subjected to analysis of variance and comparison of means. Then, calculation of total means and cluster analysis of the cultivars based on all tested indices and correlation between indices were performed. The results showed that the cultivars usually revealed different behaviors for reduction trend of each stress tolerance index in response to increase of salinity. Overall, the group of Zahidi, Piarom and Dayri cultivars exhibited more salt tolerance and better performance in saline conditions than the group of Kabkaab and Istamaran cultivars. Furthermore, all examined indices can be used in screening date palm cultivars for salt tolerance among which the indices related to root fresh and dry weights, shoot fresh and dry weights, leaf area and intact leaf percent are the most efficient ones.