Salinity is an obstacle for plant growth and the exploitation of means like cation foliar to soften the negative effects is of interest. The impacts of NaCl salinity (0, 75, 150, and 225 mM) and nano-Zn and Fe foliar applications (0 and 3 mg L −1) were examined on yield and physiological characteristics of Rosmarinus officinalis grown in an open soilless culture system. Salinity decreased root growth and above-ground plant growth (fresh and dry weight), chlorophyll a and total chlorophyll content, and zinc accumulation. Nano-Fe and Zn foliar application had positive influence on the above-ground plant growth. The results showed that Zn 2+ content was affected by the interaction between salinity and nano-Fe and Zn foliar application. The highest content of Zn 2+ was found at no saline Zn-sprayed plants. The content of Zn 2+ , hydrogen peroxide (H 2 O 2), malondialdehyde (MDA), and phenolics were affected by the independent effects of salinity or foliar application. Salinity increased the H 2 O 2 and MDA content but nano-zinc and iron spraying alleviated salinity impacts and both H 2 O 2 and MDA decreased. Nano-Fe and Zn foliar application increased total phenolics and total flavonoids content. Proline and chlorophyll a content, Na + , K + amounts, and K + /Na + ratio were affected by the salinity stress. Salinity decreased K + content and K + /Na + ratio but increased Na + and proline content with more pronounced effects at 225 mM NaCl. Overall, foliar application of both elements improved the growth and salt tolerance of rosemary and their application would be advisable to the cultivation practices.

Foliar application of micronutrients (both in common and nano-forms) to meet the nutritional demands of plants and even to overcome the stressful environments has gained great attention of agricultural systems. In our experiments, we tried to use the foliar nano-zinc and common zinc sources under salinity conditions and study their effects on some morpho-physiological traits of rosemary (Rosmarinus officinalis) as factorial experiment based on RCBD design. ANOVA results revealed the interaction effects of salinity and zinc foliar application on elemental content (K + , Na + and Zn 2+), as well as essential oil yield of the plants. Carotenoids were influenced by the salinity levels. Soluble sugars content, flavonoids, H 2 O 2 and MDA contents were influenced by individual levels of salinity and zinc foliar applications. Eventually, nano-zinc foliar spray was able to overcome the mild salinity effects on the plant growth and physiological parameters and it could be administered to the production systems and pioneer plant producers.

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