Relationship of photosynthetic capacity and proline accumulation with the growth of differently adapted populations of two potential grasses (Cynodon dactylon (L.) Pers. and Cenchrus ciliaris L.) to drought stress

Response of two populations of each of two grass species viz., Cynodon dactylon (L.) Pers. and Cenchrus ciliaris L. to drought stress was assessed in a pot experiment. One population of each grass species was collected from the Salt Range which is known for high salt and drought stress. The other population was collected from a frequently irrigated soil in Faisalabad. Eighty eight days old plants of each population were subjected for 30 d to different water stress levels [control (maintained at field capacity), 75% or 50% of field capacity). Although growth of both grass species from two different habitats decreased with increase in water deficit conditions, the Salt Range populations of both grass species produced significantly higher shoot biomass than Faisalabad populations. A significant detrimental effect of water deficit conditions was observed on chlorophyll a, chlorophyll b, chlorophyll a/b ratio, proline contents, photosynthetic rate, transpiration rate, stomatal conductance, sub-stomatal CO2 concentration and also on C-i/C-a ratio, but not on water use efficiency. Although Populations of both species from the Salt Range were more drought tolerant as compared to those from Faisalabad, it was not possible to discriminate among the populations on the basis of biochemical and physiological parameters examined in this study.