Nickel toxicity pretreatment attenuates salt stress by activating antioxidative system and ion homeostasis in tomato (Solanum lycopersicon L.): an interplay from mild to severe stress

Summary

This controlled experiment examined whether pre-activating the antioxidative defence system in tomato seedlings via mild nickel toxicity (0–30 mg L⁻¹ for three weeks) could improve adaptation to subsequent severe salt stress (75–150 mM NaCl in hydroponics; 7.5–15 dS m⁻¹ in soil). Nickel pretreatment significantly enhanced antioxidant enzyme activity and ion homeostasis (higher K+, lower Na+ retention), resulting in improved growth and yield under saline conditions, although fruit quality traits were not significantly affected. The genotype Riogrande demonstrated superior responses to nickel pretreatment compared to Green Gold, suggesting that genotypic variation influences the effectiveness of this stress-priming strategy.

Regional applicability

This study was conducted under controlled laboratory and greenhouse conditions and does not specify geographic location, limiting direct transferability to United Kingdom field conditions. The findings on salt stress tolerance in hydroponics and controlled soil systems may inform protected horticulture (glasshouse tomato production) in the UK where soil salinity is less common, but the nickel pretreatment strategy would require validation under UK climate and soil conditions before practical adoption.

Key measures

Antioxidant enzyme activities (SOD, CAT, APX, POX); Na+ and K+ uptake; plant growth metrics; fruit yield per plant; average fruit weight; fruit diameter; fruit dry matter percentage; total soluble solids; fruit juice pH; titratable acidity

Outcomes reported

The study measured antioxidant enzyme activities (SOD, CAT, APX, POX), ion homeostasis (Na+ and K+ uptake), plant growth, and yield characteristics in two tomato genotypes exposed to salt stress following nickel pretreatment. Results demonstrated that nickel pretreatment enhanced antioxidant defence mechanisms and improved growth and yield under both hydroponic and soil salinity conditions.

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