Salinity tolerance and ion accumulation in chickpea (Cicer arietinum L.) subjected to salt stress

Chickpea (Cicer arietinum L.) is considered a salt sensitive species, but some genetic variation for salinity tolerance exists. The present study was initiated to determine the degree of salt tolerance among chickpea genotypes, and the relationship between salt tolerance and ion accumulation in leaves and reproductive tissues. Three experiments were conducted in a glasshouse in Perth, Western Australia, in which up to 55 genotypes of chickpea were subjected to 0, 40 or 60 mM NaCl added to the soil to determine the variation in salt tolerance, and the association between salt tolerance and reproductive success. Pod and seed numbers, seed yield and yield components, pollen viability, in vitro pollen germination and in vivo pollen tube growth, were used to evaluate reproductive success. Leaves, flowers and seeds were sampled in the reproductive phase to measure the concentrations of sodium, potassium and chloride ions in these organs. When grown in soil with 40 mM NaCl, a 27-fold range in seed yield was observed among the 55 chickpea genotypes. The increased salt tolerance, as measured by yield under salinity or relative yield under saline conditions, was positively associated with higher pod and seed numbers, and higher shoot biomass, but not with time to 50 % flowering nor with the number of filled pods in the non-saline treatment. Pod abortion was higher in the salt sensitive genotypes, but pollen viability, in vitro pollen germination and in vivo pollen tube growth were not affected by salinity in either the salt tolerant or salt sensitive genotypes. The concentrations of sodium and potassium ions, but not chloride, in the seed were significantly higher in the sensitive (106 mu mol g(-1) DM of sodium and 364 mu mol g(-1) DM of potassium) than in the tolerant (74 and 303 mu mol g(-1) DM, respectively) genotypes. Sodium and potassium, but particularly chloride, ions accumulated in leaves and in pod wall, whereas accumulation in the seed was much lower. Considerable genotypic variation for salt tolerance exists in chickpea germplasm. Selection for genotypes with high pod and/or seed numbers that accumulate low concentrations of salt in the seed will be beneficial.