Effects of Penconazole and Nitric Oxide Application on Some Physiological and Biochemical Responses of Narcissus tazetta under Drought Stress

In this research, the impact of penconazole (PEN, 15 mg/L) and nitric oxide (NO, 100 µM) pretreatment was evaluated on some physiological and phytochemical characteristics of Narcissus tazetta plants under different drought levels (0, 5, 10 and 15%). Drought stress diminished plant growth and caused oxidative stress by introducing hydrogen peroxide (H2O2) and malondialdehyde (MDA) as oxidative stress markers. The results showed that PEN and NO relieved the drought-induced inhibitory impacts on the plant growth and regulated defense responses in N. tazetta plants. Our data suggested that PEN and NO alleviated drought-induced damages by reduction in H2O2 and MDA level in stressed N. tazetta plants. NO and PEN augmented superoxide dismutase, peroxidase and polyphenol oxidase, total phenolic content, flavonol content and flavonoid content under drought conditions, thus contributing to the improvement of the antioxidant defense system. NO and PEN induced proline accumulation as a compatible osmolyte in N. tazetta plants under drought stress. It is proposed that PEN and NO were beneficial to protect lipid peroxidation, proline accumulation and the promotion of antioxidant defense systems with imposition to drought stress.