Drought stress on electrolyte leakage, H2O2 concentration, relative water and chlorophyll content and leaf area in Carthamus tinctoriusL.

Water deficit is the most important abiotic limiting factor for plant growth and performance. Drought induces oxidative stress and improves oxygen free radicals such as hydrogen peroxide in plants. Reactive oxygen species combine with lipids and cause membrane injuries via lipid peroxidation. Membrane injuries affect selective permeability and electrolytes leak to the outside of the cell. In this research, safflower plants were irrigated up to 100, 80, 60, 40, 20% field capacity after three leaves stage for 14 days in a greenhouse based on complete randomized block design with three replications. For measuring water value needing for the pots, was used from the weightingmethod. Physiological parameters of plants were measured after plant harvesting. Results showed that drought stress had a significant effect on all traits. Electrolyte leakageand H2O2 concentration enhanced in leaves and roots with increasing of stress levels, but RWC, chlorophyll a and b contents and leaf area reduced compared with the control. The highest electrolyte leakage, H2O2 concentration in safflower plants observed under the irrigation regime of 20% field capacity. Decreasing water potential in the severe stress of 20% field capacity can induce osmotic stress, decrease chlorophyll content and by increasing membrane damages cause the death of safflower plants