Nowdays, one of the major environmental stresses challenging agricultural produce worldwide, is progressive soil salinity. The majority of the soils in the arid and semi-arid regions face salinity. This is a huge threat for agricultural sustainablitty. With salinity adding-up, plants growth and development greatly decline due to reduced osmotic potential, unbalanced nutrients available and the variations in the type and content of growth regulators which negatively influence the plant yield and productivity. Under salinity situations, using micronutrients plays a vital role in the tolerance of plant against ROS molecules. These nutrients motivate antioxidant enzymes and hence, improve plant responses to the ROS molecules generation. As a result, they improve the yield, quality and productivity of plants under stressful conditions.
Materials and Methods
An experiment was conducted to study the effects of NaCl salinity stress (0, 50, 100 and 150 mM) and Foliar application of common and Nono-form Zinc-oxide (0, 5 and 10 mg L-1) on Rosmarinus officinalis as factorial based on RCBD with three replications at 2017- 2018.
Results and Discussion
The results revealed the interaction effects of salinity levels and Zinc Foliar application on chlorophyll b content, N, P, K, Na and Zn content, leave relative water content as well as essential oil yield. The highest data for chlorophyll b was recorded with no stress × 10 mgL-1 Nono-zinc spray. Relative water content for both Zn forms (0, 5 and 10 mgL-1) was maximum with no salinity treatments. The greatest data for essential oil yield was traced with NaCl0 × 10 mgL-1 Nano-zinc and NaCl0× 10 mgL-1 Zinc Oxide. NaCl0× 5 mgL-1 Nano-Zinc increased K+content in plant. For Zn compositional content, the highest data was recorded with no-salinity × 5 and 10 mgL-1of Nano-Zinc as well as with no-salinity × 10 mg L-1 of common zinc source. Aerial parts dry weight and Fe and Mg content were affected by independent effects of salinity and Foliar application of Zn. Aerial parts dry weight and Mg content increased at no salinity stress and 50 mM salinity. Chlorophyll a and Fe content were influenced by the non salinity levels. Foliar application with 0 and 10 mg L-1nano-Zn increased Mg content in plants. Salinity is one of the predominant stressors influencing the plants throughout all their life cycle. The results revealed that salinity drastically influenced rosemary dry weight, photosynthetic pigments content, as well as Mn, Cu, and Fe content. Zn Foliar application improved aerial parts fresh weight and the content of Mg, Cu, and Fe. In general, rosmary is salinity tolerant up to 50 mM without significant reduction in yield component. Therefore, the Foliar application of Nano-Zinc as Oxide form improved yield and growth characteristics.
Salinity drastically influenced the growth and physiological responses of the plants. Using Foliar treatments was able to partially ameliorate the salinity adverse effects and, promoted the growth and productivity of rosemary. However, economical administration of Foliar treatments needs more in-depth studies.