تأثیر شوری بر وضعیت آب برگ، غلظت پرولین، کل قندهای محلول و فعالیت آنتی‌اکسیدانی گیاه ارزن پادزهری

Evaluation of certain biochemical and physiological changes under stress can provide an appropriate approach for the study of hereditary factors influencing salt stress tolerance. In this greenhouse study, the changes in water status, osmotic regulators and activity of antioxidant enzymes in leaf tissue of panic blue grass (Panicum antidotale Retz) exposed to salinity were evaluated over five consecutive weeks. Five levels of salinity (0, 70, 140, 210 and 280 mM NaCl) were applied at the 4-leaf stage. Results showed that the highest leaf relative water content (RWC) in non-saline (control) treatment, as compared with the lowest RWC in 280 mM salinity treatment, was 8.67, 31, 25, 28 and 27% in the 1st to the 5th wee, respectively. Average leaf osmotic potential showed a decreasing trend in different salinity treatments over time and was reduced from -0.717 MP in the first week to -1.26 MP in the 5th week after exposure to salinity. Total soluble carbohydrates content of the leaves was reduced with increasing the salinity level. After 28 days of exposure to salinity, the activity of ascorbate peroxidase enzyme in non-saline treatment was 40% more than the 280 mM treatment although the highest activity of ascorbate peroxidase enzyme was observed in the 70 mM treatment. Leaf RWC (r=0.62**) and membrane stability index (r=0.52**) had the most positive correlation with dry matter production of blue panic grass. In addition, increasing the DPPH radical scavenging activity (r=-0.61**) and total phenol concentration (r=-0.69**) had effective role in survival of this salt-tolerant plant. The data analysis, using stepwise regression, indicated that total phenol concentration (β= -0.722) and leaf proline concentration (β= -0.265) were the main components of salinity tolerance of blue panic grass.