Foliar application of salicylic acid enhances yield, oil quality and economic returns of Linum usitatissimum L. under different irrigation regimes

Background/Purpose Linseed ( Linum usitatissimum L.) is an important oilseed crop, but its productivity is frequently limited by water stress during critical growth stages. Salicylic acid (SA) has been reported to improve stress tolerance and crop performance. However, the interaction between irrigation regimes and SA application and their combined influence on yield, seed quality and economic returns of linseed under field conditions remain insufficiently explored. This study aimed to evaluate the effects of different irrigation regimes and foliar applications of SA on yield attributes, oil quality and economic profitability of linseed cultivation. Methods A field experiment was conducted during the rabi season of 2024-25 at the Research Farm of Chaudhary Sarwan Kumar Himachal Pradesh Krishi Vishvavidyalaya, Palampur, India. The experiment was arranged in a strip-plot design with three replications. Three irrigation regimes were evaluated: IR 1 (rainfed), IR 2 (two irrigations at branching and pre-flowering stages) and IR 3 (three irrigations at branching, pre-flowering and capsule development stages). Four foliar treatments of salicylic acid were applied at branching and pre-flowering: S 1 (water spray), S 2 (50 mg/L), S 3 (75 mg/L) and S 4 (100 mg/L). Yield attributes, seed yield, oil content, oil yield and economic returns were recorded and analysed statistically. Results Both irrigation and salicylic acid significantly influenced yield and quality traits of linseed. The highest seed yield (1557 kg ha -1 ), oil content (37.2%), oil yield (580 kg ha -1 ), net return (USD 980 ha -1 ) and benefit cost ratio (2.24) were obtained under IR 3 . Among SA treatments, 100 mg/L produced the highest seed yield (1467 kg ha -1 ), oil yield (547 kg ha -1 ), net return (USD 905 ha -1 ) and B:C ratio (2.11). The interaction of IR 3 × S 4 resulted in the maximum seed yield (1624 kg ha -1 ) and oil yield (618 kg ha -1 ). However, 75 mg/L SA showed nearly comparable performance to 100 mg/L, indicating that moderate concentrations can achieve efficient yield improvement. Conclusions Strategic irrigation at branching, pre-flowering and capsule development stages combined with foliar application of salicylic acid significantly improves linseed productivity, oil yield and farm profitability. Although 100 mg/L SA produced the highest yields, 75 mg/L was identified as the most efficient concentration due to comparable performance with potentially lower input requirements. These findings highlight the potential of integrating optimized irrigation scheduling with salicylic acid application as a climate-smart strategy for sustainable linseed production under variable moisture conditions.