The effect of NaCl salinity stress and foliar application of Cerium oxide and Nano Fe on growth and some physiological characteristics of Lavandula officinalis L.

Salinity is one of the major environmental stressors limiting the growth and development of plant in the agricultural system. Salinity affects the plants from the physiological, biological and molecular point of view. Emphasizely, salinity influence the plants growth and productivity by the induction of water stress, ionic toxicity (Na+, Cl-) and nutrients imbalances. With stress goings on, ROS molecules is produced leading to membranes oxidation damage and hence deteriorate the membranes and adversely impact the plant growth and physiological response. Na high accumulation in the soil medium interferes the nutrient balance in the soil and plant cells, leading to disturbances in nutrients uptake deficiency symptoms, oxidative damage, growth reduction and eventually death of plants. In the saline soils, Na+/K+ and Na+/Ca2+ ratios, high above the standard levels and hence the absorption and essential amounts of K+ and Ca2+ is inhibited; membranes deteriorate and the enzymatic dynamics inside cells is interrupted which is called the induced secondary stress. ROS radicals influenced the activity of chloroplast and mitochondria and eventually the plant survival is affected. Considering the main idea with the present study was to assess the effects of salinity stress on the growth and some physiological traits of Lavandula treated with foliar application in hope that the possible promising data could be advisable to the extension section.

Two separate experiments were concluded to evaluate the effects of foliar application of nano-cerium oxide and nano-Iron (0, 2.5 and 5 mg.L-1) on Lavandula officinalis L. under saline (0, 50 and 100 mM) conditions as factorial based on Completely Randomized Design in the greenhouse. In the first experiment, the effects of magnetized Iron and in the second experiment, the effect of cerium oxide were assayed on Lavandula officinalis growth and some physiological traits under salinity stress.

The results obtained from the first experiment showed that, the plant dry weight, catalase activity and Fe content were independently affected by the salinity and Fe foliar treatment. H2O2 content (4.6 µmol. g-1FW), total phenolic content (36% increases compared to the control) and oil percent (41% increases compared to the control) were influenced by interaction effects of salinity and nano Fe foliar application. The top amounts of Na (8.9 g.Kg-1), proline (94 µg.g-1FW), malondialdehyde (82 nmol.g-1 FW) and H2O2 were recorded at 100 mM salinity stress. At the second experiment, plant dry weight (25% increases compared to the control) and total phenolic content (29% increases compared to the control) were influenced by interaction effects of cerium oxide foliar application and salinity stress. Catalase activity, H2O2 and K content were influenced by sole effects of salinity and cerium oxide foliar application. 2.5 and 5 mg L-1 cerium oxide treatment increased K content (43% compared to the control) and K/Na ratio. GC/MS analysis revealed that Linalool (10.3-27.1%) and 1-8-Cineol were the major constituent of oil at NaCl50 and 100 mM × 5 mg.L-1 cerium spray.

Our results revealed that cerium oxide and nano-Fe foliar application improved the plants physiological response under no-saline condition. Salinity adversely imposed the yield, some physiological traits and elemental content of plants. Under 50 and 100 mM salinity foliar treatment were not able to mitigate salinity adverse effects except for phenolic content (both experiment), essential oil content (first experiment) and plant dry weight (the second experiment). In total, lavender is a salt sensitive plant and the idea is that to overcome salinity depression, have to experience more concentration of foliar treatment.