Effects of Nano-Zinc Oxide, Salicylic Acid, and Sodium Nitroprusside on Physiological and Enzymetic Traits of Sweet Violets Under Different Water Regims

The effects of Nano-zinc oxide (ZnO), salicylic acid (SA), and sodium nitroprusside (SNP) were studied on sweet violets under different irrigation water regimes in a factorial experiment. The factors were drought stress at three levels including irrigation at 85 (control), 65 (moderate stress) and 55 (severity stress) percent of field capacity (FC) soil water depletion and foliar application of ZnO, SA, SNP, and distilled water as a control. Means comparison showed that the best resutls was obtained from interaction 200 mg L-1 SA, with irrigation and 85 % FC,  the treatment that influenced most traits positively. Also, 300 mg L-1 SA and both SNP rates significantly outperformed the control and Nano-ZnO. The lowest stomatal conductance was related to the 200 µM SNP at 55% FC. The lowest malondialdehyde (MDA) content was observed in 200 mg L-1 SA and 85 % FC treatment. The highest relative water content (RWC) was associated with the application of 1500 mg L-1, Nano-ZnO at 85% FC. The control plants at 55% FC recorded the highest proline (46.62 μg g-1 FW). The highest peroxidase (POD) enzyme activity was related to the treatment of 1000 mg L-1 Nano-ZnO and the highest ascorbate peroxidase (APX) to the treatment of 1500 mg L-1 Nano-ZnO at 55% FC.