Drought stress effects on three cultivars of Eragrostis curvula:: photosynthesis and water relations

Water stress effects were studied on three cultivars of Eragrostis curvula. Leaf water potential, RWC, total plant leaf area, green dry weight mass percentage and CO2 gas-exchange were measured during the onset of stress and after recovery. After 3 days of water stress, RWC of cv Tanganyika plants was around 30-40% of controls, while RWC of cvs Ermelo and Consol was around 50-60% of controls. However midday and predawn water potentials were lower in cvs Tanganyka and Ermelo than in ev Consol. After re-watering, RWC and water potentials recovered only in Consol plants. A strong decrease of leaf area was recorded in cvs Ermelo and Consol during water stress (about 91-94% less than the leaf area of controls). Photosynthesis decreased as a function of the degree of water stress severity in all cultivars. Also, light saturated photosynthesis, CO2 quantum yield and light at which saturated photosynthesis occurred, were strongly reduced by water stress. Recovery of photosynthesis was found in cv Consol after five days re-watering. Cv Consol showed a better conservation of water and higher resistance to water stress than the other two cvs.