Enhancement of yield and fruit quality of strawberry under deficit fertigation via sodium hydrosulfide and L-cysteine

Strawberry (Fragaria × ananassa) is a high-value crop whose yield and fruit quality are extremely susceptible to water and nutrient limitations, especially in greenhouse and soilless cultivation. Developing strategies to maintain productivity under reduced fertigation is therefore crucial. This study investigated whether applying sulfur-related compounds, specifically sodium hydrosulfide (NaHS) and L-cysteine (Cys), to the strawberry cv. Sabrina could counteract the detrimental effects of reduced nutrient supply. Plants were treated with NaHS (500 and 1000 µM) or Cys (500 and 1000 µM) under two fertigation levels (100 mL and 140 mL as control). Applying reduced fertigation alone resulted in physiological constraints, whereas NaHS and Cys significantly increased yield, improved fruit quality traits, and enhanced antioxidant capacity compared with untreated plants. Also, activities of phenylalanine ammonia lyase, catalase, and ascorbate peroxidase were significantly increased. The improvements were associated with higher levels of phenolics, anthocyanins, and vitamin C, indicating a coordinated strengthening of the enzymatic and non-enzymatic defense systems. Overall, foliar applications of 1000 µM NaHS and 1000 µM Cys under reduced fertigation schedules were most effective in improving strawberry productivity and fruit quality. This study highlights the potential of sulfur-based elicitors as practical, eco-friendly tools to improve stress tolerance, preserve nutritional value, and optimize water and nutrient use in controlled cultivation systems.