Organic priming strategies enhance antioxidant defense and suppress corm rot in saffron: role of Trichoderma and walnut leaf powder.

Abstract

Saffron (Crocus sativus L.) cultivation has declined sharply in traditional regions due to biotic and abiotic stresses, with Fusarium acuminatum-induced corm rot emerging as a major threat. Given saffron's genetic sterility and concerns over chemical fungicides, sustainable alternatives are essential. This study demonstrates that organic amendments, particularly Trichoderma bioformulation (T₃) and walnut leaf powder (T₇), effectively suppress corm rot, with lowest infection percentage recorded in T₇ (13.32%), followed by T₃ (19.89%). Notably, the chemical treatment T₆ (NPK) showed a comparatively higher disease percentage area (56.43%) than the untreated control (T₀) (47.55%). Trichoderma bioformulation activated jasmonic acid- and ethylene-mediated induced systemic resistance (ISR), regulated sugar metabolism, and enhanced antioxidant enzyme activity. Walnut leaf powder improved resistance by boosting antioxidant potential and osmotic balance, linked to its high phenolic content and osmolyte accumulation. Both treatments demonstrated complementary mechanisms, combining direct antifungal action with host defense activation, highlighting their potential as eco-friendly alternatives for integrated management of saffron corm rot. The study demonstrates that host-specific organic amendments can suppress pathogen development and reprogram host biochemical defences, highlighting the specificity of organic amendments for sustainable saffron health management.