Early view

Waleed Iqbal, Uzair Ahmed, Muhammad Zahir Afridi, Muhammad Ayaz, Hamza Azeem Khan

Abstract

Freshwater scarcity is increasing reliance on deficit irrigation, which reduces crop productivity. Foliar salicylic acid is a low-cost means of alleviating water-stress damage, but its effectiveness across levels of water availability remains unclear. A greenhouse pot experiment evaluated wheat cultivar Zincol-16 under four foliar salicylic acid concentrations (0, 0.5, 1.0 and 1.5 mmol L-1) and four irrigation regimes (40, 60, 80 and 100% of field capacity) in a factorial randomized complete block design with three replications. At 1.5 mmol L-1, salicylic acid increased grain weight per pot by 8.1% under severe deficit (40% of field capacity) and by 25.9% under full irrigation, with plant height and spike length also responding most under full irrigation. In contrast, the same concentration raised relative water content by 18.5% under severe deficit but by only 6.7% under full irrigation, and lowered proline and malondialdehyde by 28.4 and 27.1% under severe deficit, where peroxidase, catalase and ascorbate peroxidase activities were also highest. Multivariate and path analyses indicated that water availability dominated trait variation and associated salicylic acid positively with growth and yield. Foliar salicylic acid therefore mainly protected plants under severe water stress but gave its largest yield gains under adequate irrigation. The 1.5 mmol L-1 concentration was generally the most effective, although field validation is required.

Keywords

antioxidant enzymes, deficit irrigation, oxidative stress, path analysis, Triticum aestivum

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