Timing-dependent responses of Fusarium graminearum suppression and malting quality in barley following PSP1 elicitor...

Plant defence elicitors have emerged as promising tools and a sustainable alternative to enhance crop resilience. In barley, the potential benefits of elicitors on agronomic performance remain insufficiently understood. The present study aimed to evaluate the effects of the defence elicitor Plant Stimulator and Protector 1 (PSP1) on the Fusarium graminearum-barley pathosystem in the Argentine Pampas, considering application timing.

Field experiments were conducted in 2022 and 2023 using two contrasting commercial two-row spring barley genotypes. The PSP1 was applied at three phenological stages: tillering (T1), stem elongation (T2), and heading (T3), with plots artificially inoculated with F. graminearum (DC.55). Disease parameters, yield components, commercial grain traits and industrial malting quality variables were assessed.

The results showed that applications close to heading resulted in low, non-significant reductions in FHB incidence (≤10%) and severity (≤5%) relative to earlier applications. Grain yield components were largely unaffected by PSP1, whereas malting quality showed a clear change in response to defence activation. Late applications tended to negatively affect malt extract, friability, and the Kolbach index (≤5%), as well as FAN and filtration time (≤25%) compared to the control. In contrast, malt protein, grain size, and wort pH increased. Under low-moderate FHB pressure, PSP1 application timing was a key determinant of barley agronomic and technological outcomes, with earlier applications linked to better malting quality. These results provide novel field-based insights into elicitor use in barley, supporting the design of future multi-environment studies to optimize the deployment of elicitor-based strategies.