Study on effects of salicylic acid and nanosilicon on some morphophysiological characteristics and essential oil of Lallemantia iberica (M.B.) Fisch. & C.A. Mey. under salinity stress

Abstract

This study was conducted to investigate the effects of salicylic acid (SA) and nanosilicon (n-Si) on some morphophysiological characteristics and essential oil of Lallemantia iberica under salinity stress and uncontrolled greenhouse conditions as a factorial experiment based on the randomized complete block design in 2018. The experimental factors included sodium chloride (0, 50, and 100 mM), SA (0, 1, and 2 mM), and n-Si (0, 0.5, and 5 mM). The SA and n-Si treatments were applied at the four-leaf stage (once every seven days) and the salinity treatment was applied at the six-leaf stage of the plant (once every four days) until fully ripening seeds of the plant (yellowing 90% of the leaves and capsules). The results showed that under salinity stress, the plant traits including height, aerial parts dry weight, chlorophyll content, and seed yield decreased and proline and essential oil increased. The application of SA and n-Si improved these traits under salinity stress. The main constituents of L. iberica essential oil included linalool (25%), geraniol (16%), β-cubebene (10.6%), menthyl acetate (9.8%), valencene (3.5%), germacrene-D (2.4%), β-caryophyllene (2.3%), and limonene (1.3%), all of which increased in the salinity treatments compared to the control. The application of SA and n-Si under salinity stress conditions increased limonene, linalool, geraniol, β-cubebene, β-caryophyllene, and valencene and decreased menthyl acetate and germacrene D. In general, the results of this study showed that the application of SA and n-Si could increase the tolerance of L. iberica to salinity stress by creating the osmotic regulation, protecting the content of photosynthetic pigments, and reducing oxidant damage.