Physiological and nutritional indicators of tolerance to salinity in chickpea plants growing under symbiotic conditions

Alterations of plant growth, nitrogenase activity and nutrient concentration as a consequence of salt treatments were studied in five chickpea (Cicer arietinum L.) cultivars from Spain and Syria. Plants, in symbiosis with Mesorhizobium ciceri ch-191 strain, were grown under controlled conditions for 32 days and subjected to salinity stress. Parameters of growth and nitrogen fixation were affected under salt stress in all cultivars tested; plant dry weight decreased by about 15% in ILC1919; and in Sirio and Lechoso about 50% with the highest salt dosage (100 mM NaCl). ILC1919 showed a less growth accompanied by a lower dry matter formation under low salt conditions compared with most of the salt sensitive cultivar. Nitrogenase activity decreased by about 60% in the salt-resistant cultivar (cv. ILC1919) and more than 90% in salt-sensitive cultivars (cv. Sirio and Lechoso) with the highest salt dosage during the reproductive growth. We show that the higher NaCl tolerance of the ILC1919 cultivar is supported by the less N2 fixation inhibition, a higher root-to-shoot ratio, normalized nodule weight and shoot K/Na ratio; and a reduced foliar accumulation of Na+. Moreover, our results reveal the effectiveness of these nutritional and physiological indicators in the selection of salinity-tolerant chickpea plants growing under symbiotic conditions.