Foliar Application of Nano Fe and Se Affected the Growth and Yield of Pelargonium graveolens under Salinity Stress

Introduction  NaCl Salinity is one of the major environmental stressors affecting agricultural production everywhere. Salinity impacts the plants by the osmotic stress, nutritional imbalance with plants cells and by reducing the nutrients absorption and reactive oxygen species over-generation, as well as by ionic competition for the absorption, translocation, distribution and ion toxicity inside plants. Under salinity stress, plants develop various physiological and biochemical mechanisms to overcome this conditions, like ion homeostasis and compartmentalization, ion uptake, biosynthesis of osmoprotectants, activation of antioxidant enzymeic (superoxide dismutase, catalase, ascorbate peroxidase and glutathione peroxidase) and nonenzymic compounds (proline) to overcome salinity stress. Optimum nutrition under stressful saline conditions is important to overcome the problem and to produce optimum yield. Pelargonium graveolens is a plant commonly used in food and pharmaceutical industries. Iran has favorable micro-climates for the Pelargonium graveolens, production, and since this plants is in common use with diverse industries, this experiments was conducted to study the effects of foliar spray with Se and nano Fe on growth and physiological traits Pelargonium graveolens under NaCl salinity depression Materials and Methods  Two separate experiments were concluded to evaluate the effects of foliar application of selenium and nano-Iron (0, 1.5 and 3 mgL-1) on pelargonium under saline (0, 50 and 100 mM) conditions as factorial based on Completely Randomized Design. In the first experiment, the effects of magnetized Iron and in the second experiment, the effect of selenium were assayed on pelargonium growth and physiological traits (plant dry weight, enzymic activity, elemental content, essential oil percent and oil constituents) under salinity stress. Results and Discussion  The results obtained from the first experiment showed that, the aerial parts dry weight, Na, Fe and H2O2 content, catalase activity and oil percent of Pelargonium graveolens were independently affected by the salinity and (1.5 and 3 mgL-1) Fe foliar treatment. At the first experiment the highest amount of K/Na ratio, flavonoid content, K content, malondialdehyde, proline and superoxide dismutase activity were influenced by salinity stress. The top amount amount of plant dry weight, Fe content, K/Na, Na and superoxide dismutase activity were recorded at control plants. The top amounts of Na, proline, malondialdehyde, H2O2 content were recorded at 100 mM salinity stress. control and 50 mM NaCl increased oil percent in plants. Foliar spray with 1.5 and 3 mgL-1 Fe increased catalase, yield, phenolic content and oil percent in plants. At the second experiment; aerial parts dry weight, proline and flavonoid content were influenced by salinity stress. Catalase activity, malondialdehyde, superoxide dismutase activity and H2O2 content were influenced by sole effects of salinity and Se foliar application. Under non saline condition, plant dry weight, superoxide dismutase activity, K content were increased in plant. With increasing salinity to 100 mM NaCl, proline, malondialdehyde and H2O2 content were increased. Se, Na content and K/Na ratio in the second experiment was influenced by the interaction effects of salinity and foliar spray. At the second experiment, the top amount of K/Na ratio were recorded at NaCl0 × 1.5 and 3 mgL-1 Se spray. The top amounts of Na were recorded at NaCl0 × no foliar application. The superoxide dismutase activity, malondialdehyde and K+ were responded to the individual effects of salinity and Se treatment. The highest amounts of total phenolic content was attained by (1.5 and 3 mgL-1) nano Fe and Se treatment in both experiment. With salinity of 50 and 100 mM, the flavonoids contend was increased at both experiments. Foliar spray with 1.5 and 3 mgL-1 Nano Fe and Se increased catalase activity in plants. 1.5 and 3 mgL-1 Se and nano Fe foliar application reduced H2O2 content in plant at both experiment. GC/MS analysis revealed that β-citronellol (12.5-20.5%) was the major constituent with control treatment Citronelly formate (10.75-25.2%) were the dominant constituents of oil control plants. Β-Thujone (12.61%), trans-Rose oxide (2.85- 9 %) and the highest amounts of Aromadendrene (5.42 %) only recorded at control plants. Salinity stress and foliar spray had negative effects on α-Pinene biosynthesis and the highest amounts of α-Pinene was recorded in control plants. The top amounts of Geranyl formate (0.7-7.8 %) was recorded at NaCl50 × 1.5 mgL-1 Fe spray. Y- muurolene (0.4 – 4.06 %) biosynthesis increased at NaCl50 × 1.5 mgL-1 Se. Conclusion  Salinity stress involves changes in metabolic processes and various physiological traits, controlled by salinity stress severity. In total, salinity had negative effects on the growth and physiological responses of plants, however, foliar treatment with Se and Fe improved some physiological traits of Pelargonium graveolens.