Effects of Salicylic Acid Application on Pollen Viability and Germination of Date Palm (Phoenix dactylifera L.) under Heat and Cold Stress

Résumé fourni par la source

Date palm (Phoenix dactylifera L.) reproductive success is highly vulnerable to temperature fluctuations, which impair pollen viability and germination. This study investigated whether exogenous salicylic acid (SA) enhances pollen performance under heat and cold stress in two male cultivars (‘Jarvis’ and ‘Ghanami Akhdar’). Pollen grains were exposed to four temperatures (12 ± 1 °C, 25 ± 1 °C, 35 ± 1 °C, and 40 ± 1 °C) and four SA concentrations (0, 1, 3, 5 mg L⁻¹) in a factorial experiment. At optimal temperature (25 °C), ‘Ghanami Akhdar’ exhibited higher pollen viability (53.6%) and pollen tube length (127.9 µm) than ‘Jarvis’ (49.9% and 111.0 µm, respectively). Moderate heat stress (35 °C) markedly reduced pollen viability, but SA at 1–3 mg L⁻¹ significantly improved performance, raising viability up to 86.2% and enhancing germination at 72 hours. Under prolonged heat exposure, 5 mg L⁻¹ SA maintained viability at 67.6% but did not fully restore germination. ‘Ghanami Akhdar’ showed stronger responsiveness to SA than ‘Jarvis’, recovering viability to 87.6% at 35 °C with 3 mg L⁻¹ SA. In contrast, extreme temperatures (12 °C or 40 °C) completely inhibited germination, and SA was ineffective under these conditions. Overall, SA was effective in alleviating moderate heat stress but ineffective under severe temperature extremes. These findings indicate that SA (1–3 mg L⁻¹) can enhance pollen performance under suboptimal temperatures up to 35 °C, with cultivar‑dependent variability in responsiveness.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.