Salt sensitivity in chickpea is determined by Na(+) toxicity, whereas relatively high leaf tissue concentrations of Cl(-) were tolerated, and the osmotic component of 60-mM NaCl was not detrimental. Chickpea (Cicer arietinum L.) is sensitive to salinity. This study dissected the responses of chickpea to osmotic and ionic components (Na(+) and/or Cl(-)) of salt stress. Two genotypes with contrasting salt tolerances were exposed to osmotic treatments (-0.16 and -0.29 MPa), Na(+)-salts, Cl(-)-salts, or NaCl at 0, 30, or 60 mM for 42 days and growth, tissue ion concentrations and leaf gas-exchange were assessed. The osmotic treatments and Cl(-)-salts did not affect growth, whereas Na(+)-salts and NaCl treatments equally impaired growth in either genotype. Shoot Na(+) and Cl(-) concentrations had markedly increased, whereas shoot K(+) had declined in the NaCl treatments, but both genotypes had similar shoot concentrations of each of these individual ions after 14 and 28 days of treatments. Genesis836 achieved higher net photosynthetic rate (64-84 % of control) compared with Rupali (35-56 % of control) at equivalent leaf Na(+) concentrations. We conclude that (1) salt sensitivity in chickpea is determined by Na(+) toxicity, and (2) the two contrasting genotypes appear to differ in 'tissue tolerance' of high Na(+). This study provides a basis for focus on Na(+) tolerance traits for future varietal improvement programs for salinity tolerance in chickpea.
Keywords: Chloride; Cicer arietinum L.; Ion ‘exclusion’; NaCl stress; Photosynthesis; Salt tolerance; Specific ion or osmotic stress; ‘Tissue tolerance’ of Na+.