Salt Stress Delayed Flowering and Reduced Reproductive Success of Chickpea (Cicer arietinum L.), A Response Associated with Na+ Accumulation in Leaves

Salinity is known to reduce chickpea yields in several regions of the world. Although ion toxicity associated with salinity leads to yield reductions in a number of other crops, its role in reducing yields in chickpea growing in saline soils is unclear. The purpose of this study was to (i) identify the phenological and yield parameters associated with salt stress tolerance and sensitivity in chickpea and (ii) identify any pattern of tissue ion accumulation that could relate to salt tolerance of chickpea exposed to saline soil in an outdoor pot experiment. Fourteen genotypes of chickpea (Cicer arietinum L.) were used to study yield parameters, of which eight were selected for ion analysis after being grown in soil treated with 0 and 80mm NaCl. Salinity delayed flowering and the delay was greater in sensitive than tolerant genotypes under salt stress. Filled pod and seed numbers, but not seed size, were associated with seed yield in saline conditions, suggesting that salinity impaired reproductive success more in sensitive than tolerant lines. Of the various tissues measured for concentrations of Cl-, Na+ and K+, higher seed yields in saline conditions were positively correlated with higher K+ concentration in seeds at the mid-filling stage (R-2=0.55), a higher K+/Na+ ratio in the laminae of fully expanded young leaves (R-2=0.50), a lower Na+ concentration in old green leaves (R-2=0.50) and a higher Cl- concentration in mature seeds. The delay in flowering was associated with higher concentrations of Na+ in the laminae of fully expanded young leaves (R-2=0.61) and old green leaves (R-2=0.51). We conclude that although none of the ions appeared to have any toxic effect, Na+ accumulation in leaves was associated with delayed flowering that in turn could have played a role in the lower reproductive success in the sensitive lines.