The present study was aimed to biosynthesize selenium nanoparticles (SeNPs) and assess their foliar applications to improve the growth of wheat plants under controlled irrigation and drought stress. Bud aqueous extract of Allium sativum L. was used as a reducing and stabilizing agent of SeNPs followed by their optical and morphological characterization by using ultraviolet-visible spectroscopy, scanning electron microscopy, Fourier-transform infrared, and energy dispersive X-ray analysis. Various concentrations of SeNPs (10, 20, 30, and 40 mg/L) were applied exogenously to drought-tolerant (V1) and drought-susceptible (V2) wheat varieties at the trifoliate stage. Under the positive control conditions, plants were irrigated with 450 mL of water/pot (100% field capacity); and under water-deficit environment, plants were irrigated with 160 mL of water/pot (35% field capacity). Remarkable increase in plant height, shoot length, shoot fresh weight, shoot dry weight, root length, root fresh weight, root dry weight, leaf area, leaf number, and leaf length has been observed when 30 mg/L concentration of SeNPs was used. However, the plant morphological parameters decreased gradually at higher concentrations (40 mg/L) in both selected wheat varieties. Therefore, 30 mg/L concentration of SeNPs was found most preferable to enhance the growth of selected wheat varieties under normal and water-deficient conditions.

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It is imperative to understand the synergetic actions of melatonin (MET) and salicylic acid (SA) in counteracting the negative effects of drought. A pot experiment was performed to investigate the interactive effects of exogenously applied MET and SA on morphology, physiology, and biochemical characteristics of drought stressed canola (Brassica napus). METHODS:Two cultivars (Super canola and Faisal canola) were used. MET (0.1 µM) and SA (0.50 mM) were applied as seed priming, and as foliar spray. Plants were exposed to severe drought stress (45% eld capacity) at reproductive stage. RESULTS:Subjecting canola cultivars to drought caused signi cant reduction in shoot length (19%), plant fresh (15%) and dry (17%) biomass, yield (30%) and photosynthetic attributes (43%). Increased activity of free amino acids (20%), total soluble sugars (5%), and different antioxidant enzymes like catalase (27%), peroxidase (23%), superoxide dismutase (20%) and ascorbate peroxidase (35%) were recorded under drought. Seed priming, and foliar application of MET and SA increased growth and yield of canola cultivars. Priming of seeds with MET as well as synergetic application of MET priming and SA foliar spray were the most effective treatments among all, showing the greatest growth criteria (22% increase in plant height, 46% in fresh and 40% in dry biomass), yield components (49%) and endogenous MET (17%) and SA (16%) activity. Super canola cultivar showed better growth than Faisal canola. CONCLUSION:Study showed that synergetic application of MET and SA has the potential to induce stress resistance and enhance canola plants growth under drought.

Aims Understanding the interactive actions of melatonin and salicylic acid in counteracting the negative effects of drought is imperative for increasing growth and yield of canola. Here we discuss the interactive effects of exogenously applied melatonin (MET) and salicylic acid (SA) on morphology, physiology, and biochemical characteristics of drought stressed canola plants. Methods Two cultivars of canola (Super canola and Faisal canola) were used. MET (0.1µM) and SA (0.50mM) were applied in two ways, i.e., as seed priming and as foliar spray. Plants were exposed to severe drought stress of 45% field capacity at reproductive stage. Results Subjecting canola cultivars to drought caused significant reduction in shoot length (19%), plant fresh (15%) and dry (17%) biomass, yield (30%), photosynthetic attributes (43%), meanwhile enhanced free amino acids (20%), total soluble sugars (5%), and different antioxidant enzymes like catalase (27%), peroxidase (23%) and superoxide dismutase (20%) Seed priming, and foliar application of MET and SA resulted in significant increase in growth parameters and yield attributes of both canola cultivars via improving photosynthetic attributes and activity of compatible solutes and antioxidant enzyme systems. Priming of seeds with MET as well as MET priming combined with SA foliar spray were the most effective treatments of all, showing 22% increase in plant height, 46% in fresh and 40% in dry biomass and yield components (49%) of canola cultivars at either drought stress or normal irrigation. Conclusions The combined application of MET and SA has the potential to enhance canola plants growth under drought.