Hassan Bayat - Department of Horticultural Science, College of Agriculture, University of Birjand, Birjand, Iran
Basireh Shahraki - Department of Horticultural Science, College of Agriculture, University of Birjand, Birjand, Iran
Mohammad Hossein Aminifard - Department of Horticulture and Special Plants Regional Research Centre, Faculty of Agriculture, University of Birjand, Iran
Farhad Azarmi-Atajan - Department of Soil Science and Engineering, College of Agriculture, University of Birjand, Birjand, Iran

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 (۱.۱ (control) and ۶.۱ dS m-۱) and three levels of foliar spray (۰, ۲.۵ mM Si and nano-Si) with ۴ 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 (۴۷ and ۷۱%) and field (۸۶ and ۹۴%) conditions, respectively. Foliar application of nano-Si enhanced the flower total phenols of salt-stressed plants by ۷۶% (greenhouse) and ۵۰% (field), respectively. Under saline conditions, the use of nano-Si increased the flower antioxidant activity in the field by ۱۷% 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.

Antioxidants, flowering, Growth, Total soluble sugar, Water relation