Effect of polyethylene glycol induced drought stress on photosynthesis in two chickpea genotypes with different drought tolerance.

Responses of parameters related with photosynthesis and the involvement of various factors in photosynthetic damage in two chickpea genotypes, Gokce (tolerant) and Kusmen (sensitive) under drought stress were assessed. Photosynthetic pigment content decreased under drought stress in two genotypes. Significant decreases in gs, Pn and E were determined in Kusmen. No significant change in these parameters was measured in Gokce under drought stress. Fv/Fm, ΦPS2 and ETR decreased in drought stressed plants of Kusmen as compared to control plants however Fv/Fm, ΦPS2 and ETR did not change in Gokce under drought stress. Increases in NPQ were determined under stress in both genotypes. Drought stress did not affect rubisco activity and rubisco concentration in Gokce while, the activity and the content declined in Kusmen. The drought tolerance of the Gokce genotype is a consequence of a balance among leaf water potential, stomatal conductance, photosynthesis, and transpiration. On the other hand, photosynthesis in Kusmen may be not only restricted by stomatal limitations but also by non-stomatal limitations under drought stress.