Evaluation of salicylic acid, zinc Nano-oxide and sodium nitroprusside pre-treatments on some physiologic parameters and enzymatic activity of sweet violet under water-deficit stress conditions

Sweet violet (Viola odorata) is a perennial herbaceous plant with ornamental and medicinal properties. The purpose of this study was to investigate the effect of different levels of water-deficit and spraying with salicylic acid, sodium nitroprusside and zinc Nano-oxide on physiological parameters, secondary metabolites and enzymatic activity of sweet violet. Factorial experiment in completely randomized design was performed with two factors; water-deficit stress at ۳ levels (۵۵, ۶۵ and ۸۵% of field capacity or FC of pot soil) and sprays including salicylic acid (۲۰۰ and ۳۰۰ mg/l), zinc Nano-oxide (۱۰۰۰ and ۱۵۰۰ mg/l) and sodium nitroprusside (۲۰۰ and ۳۰۰ μM) in three replications. The results showed that with increasing water-deficit stress, the amount of phenolic compounds, proline and phytol, as well as the percentage of secondary metabolites, antioxidant enzyme activity and plasma membrane stability increased. The highest phenolic compounds (۵۷.۰۷ mg/galic acid/g D.W.) and proline content (۵۲.۴۷ mg/kg F.W.) were obtained in the treatment of ۳۰۰ μM sodium nitroprusside at ۵۵% of field capacity. The highest activity of superoxide dismutase (۱.۹۴ EU/mg/pro./min), catalase (۰.۱۹۸ EU/mg/pro./min) and polyphenol oxidase (۰.۲۴۸ EU/mg/pro./min) were obtained in treatments of ۲۰۰ mg/l salicylic acid and ۲۰۰ and ۳۰۰ μM sodium nitroprusside, respectively, in ۵۵% FC. The highest amount of phytol (۲.۸۷%) belonged to the control treatment in ۵۵% of FC. The highest amount of sodium (۲۸.۶۰ mg/kg) and phosphorus (۰.۶۰ mg/kg) in control plants in ۵۵% stress and potassium (۴.۲۹ mg/kg), iron (۳۰۶ mg/kg F.W.) and dry matter percentage of shoots (۲۶.۲۳) and roots (۲۷.۶۰) was observes in spraying with ۱۰۰۰ mg/l of zinc nanoparticles in stress ۸۵%, ۱۵۰۰ mg/l zinc oxide in stress ۶۵%, ۲۰۰ μM salicylic acid in stress ۸۵% and ۱۰۰۰ mg/l of zinc Nano-oxide in ۵۵% stress, respectively. Totally, the use of ۲۰۰ mg/l of salicylic acid as spray, in addition to improving the growth and developmental conditions of sweet violet, decreased the negative effects of water-deficit stress and increased plant resistance to water-deficit.  

Keywords:

Salicylic acid , Sodium nitroprusside , Zinc oxide nanoparticle , Water stress , Sweet violet , Secondary metabolites , Antioxidant enzymes , آنزیم های آنتی اکسیدانی , ذرات نانو , گیاهان زینتی- دارویی , متابولیت های ثانویه