Characterization of Salt-Tolerant Cultivars of Date Palm Based on Morphological and Biochemical Responses Under Salinity Stress

Abiotic stress, especially salinization, is considered a major soil problem in arid and semiarid regions. To combat salinization, halophytes such as date palms are grown in these areas. However, less information is available on the morphological and biochemical responses of different date palm cultivars under high salinity. In this regard, eight cultivars of date palm were selected and treated with different salinity levels to check the adaptive capabilities of these cultivars against salt stress in terms of morphological and biochemical attributes. The objective of the current study was to screen these cultivars for tolerance or susceptibility to salt stress (0, 50, 100, and 200 mM NaCl). The results of the morphological parameters revealed the negative impact of salt stress on the morphology. Higher concentrations of salt reduced the plant height (Haleemi, Dahakki, Sanduri, Saghoi, Tarwali, and Hamanwali), the number of leaves (Haleemi, Basrawali, Dhakki, Sanduri, Saghoi, and Gajjar),leaf length (Haleemi, Dhakki, Sanduri, Saghoi, and Hamanwali), leaf width (Sanduri), leaf area (Haleemi, Sanduri, Saghoi, Tarwali, and Hamanwali), fresh weight (Halimi, Dhakki, Sanduri, Saghoi, and Tarwali), dry weight % (Halimi, Basrawali, Dhakki, Sanduri, Saghoi, Tarwali, Hamanwali, and Gajjar) and root length (Haleemi, Basrawali, Dhakki, Sanduri, and Gajjar) in most of the cultivars. Generally, it was observed that leaf tissues showed a significant ( p <= 0.05) increase in the superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) activities with the increasing salt concentrations. Current analysis showed that salinity significantly ( p <= 0.05) decreased the accumulation of total phenolic contents (TPC) in the leaf tissues of Haleemi, Basrawali, Dhakki, Sanduri, Saghoi, Tarwali, Hamanwali, and Gajjar. However, a reduction in the carotenoid contents in cultivars (Haleemi, Basrawali, Dhakki, Sanduri, Saghoi, Tarwali, Hamanwali, and Gajjar) was noted with an increase in the salt concentration. Salt stress significantly reduced the anthocyanin contents in some cultivars (Haleemi, Basrawali, Sanduri, Saghoi, Tarwali, Hamanwali, and Gajjar). This species is highly adapted to salt stress conditions by the evolution of an osmoregulation mechanism. These results suggest that although date palm is tolerant of high salinity, there is variation in tolerance among different cultivars. Based on the recorded parameters, it is concluded that Saghoi was the most salt -tolerant cultivar out of the test ones, followed by Sanduri, Tarwali, and Hamanwali, respectively.