Induction of multiple defense phytohormones enhances cucumber resistance against damping off pathogens via application of fortified composts

• Microorganisms’ fortified composts can suppress cucumber damping-off disease. • Fortified composts enhance cucumber growth under both the greenhouse and field condition. • Fortified composts treatments increased the defense phytohormones (Ethylene, Jasmonic acid, Salicylic acid) level in treated plants. Globally, cucumber damping-off disease is one of the most prevalent and detrimental soil-borne diseases, resulting in substantial crop yield losses. The purpose of this research is to examine the suppressive effect of fortified composts on disease suppression, induction of defense phytohormones, and improvement of fruit quality. Four types of compost were used; compost alone (C1); Bacillus subtilis fortified compost (C2), Trichoderma viride fortified compost (C3), and a combination of both microorganisms fortified compost (C4). In pots, the highest disease suppression was observed with C4 reached 68, 73, 74 % against Rhizoctonia solani, Pythium ultimum and pathogen consortium, respectively. Overall, C4 enhanced plant growth more effectively than all other types. Furthermore, the defense related phytohormones levels such as ethylene, salicylic acid and jasmonic acid were elevated one week post planting compared to the control. In field, alleviation of disease symptoms reached 15.5, 33, 44.5, 61.5 % for C1, C2, C3, C4, respectively. Moreover, there was a significant improvement in plant growth and yield. Evaluation of fruit profiles such as total soluble solids, sugar, vitamin C and protein revealed significant nutritional restoration and enhancement. Results indicated that incorporation of fortified compost may be a potential tool in integrated disease management.