Interactive Influence of Silicon and Salicylic Acid on Physiological and Biochemical Responses of Cucumber Seedlings to Salt Stress

Document Type : Original Article

Authors

1 Department of Horticulture, Shahid Bahonar University of Kerman, Kerman, Iran

2 Department of Biology, Shahid Bahonar University of Kerman, Kerman, Iran

3 Department of Horticultural Sciences, Faculty of Agriculture, Vali-e-Asr University of Rafsanjan, Rafsanjan, Iran and Elemental Analysis Unit, Central Research and Experimental Laboratory, Shahid Bahonar University of Kerman, Kerman, Iran

Abstract
This study evaluated the interactive effects of silicon (Si; 1.5 mM) and salicylic acid (SA; 10 and 15 µM) on cucumber (Cucumis sativus L.) seedlings under non-saline and saline (80 mM NaCl) conditions using a factorial experimental design. In saline and non-saline condition, significant Si × SA interactions were detected for most growth, physiological, and biochemical traits. Under non-saline conditions, the Si + SA10 interaction increased leaf area, shoot dry mass, and total chlorophyll by 8–17% relative to the control, whereas Si + SA15 showed minimal effects. Under salinity, interaction effects were markedly amplified: compared with the control, Si + SA10 increased leaf area by 40%, shoot dry mass by 57%, total chlorophyll by 44%, carotenoids by 61%, and shoot K⁺ content by 62%, while reducing shoot Na⁺ accumulation by 36%. Oxidative stress markers were strongly suppressed by the interaction, with reductions of 61% in malondialdehyde, 50% in hydrogen peroxide, and 50% in ion leakage. Although antioxidant enzyme activities were not further enhanced by the interaction, Si + SA10 significantly increased non-enzymatic antioxidants, including phenolics (58%), flavonoids (30%), and anthocyanins (49%), and substantially elevated shoot Si accumulation. In contrast, the Si + SA15 interaction produced consistently weaker responses. These findings demonstrate that salt tolerance in cucumber is maximized through a concentration-dependent interaction between silicon and salicylic acid, with low-dose SA synergistically enhancing Si-mediated protection primarily via improved ion balance and non-enzymatic antioxidant defense.

Keywords


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Volume 3, Issue 1
Winter 2026
Pages 31-42

  • Receive Date 10 October 2025
  • Revise Date 20 December 2025
  • Accept Date 05 January 2026
  • First Publish Date 05 January 2026
  • Publish Date 01 March 2026