Alleviating adverse effects of salt stress in pot marigold (Calendula officinalis L.) by foliar spray of silicon and nano-silicon under greenhouse and field conditions

Purpose: In order to assay the impact of silicon (Si) and nano-Si on morphological and physiological traits of pot marigold (Calendula officinalis L.) under salt stress conditions, an experiment was conducted under greenhouse and field conditions. Research Method: The experiment was based on a completely randomized design including two levels of saline water (1.1 (control) and 6.1 dS m-1) and three levels of foliar spray (0, 2.5 mM Si and nano-Si) with 4 replications. Findings: Salinity stress decreased the vegetative and flowering parameters of pot marigold in the both conditions. Supplemental Si and nano-Si increased the dry weight of flowers under salt stress in the greenhouse (47 and 71%) and field (86 and 94%) conditions, respectively. Foliar application of nano-Si enhanced the flower total phenols of salt-stressed plants by 76% (greenhouse) and 50% (field), respectively. Under saline conditions, the use of nano-Si increased the flower antioxidant activity in the field by 17% in comparison to the control. Supplemental Si and nano-Si could reduce the negative impacts of salinity through increasing enzymatic and non-enzymatic antioxidants, accumulating soluble sugars, improving water relations, and enhancing chlorophyll content. Research limitations: No limitations were found. Originality/value: Based on the results of present study, the use of Si and nano-Si improved the growth and physiological characteristics of pot marigold under saline conditions.