ÓLEOS ESSENCIAIS NA INDUÇÃO DE RESISTÊNCIA E NO MANEJO DO OÍDIO DA SOJA

Abstract

Soybean is one of the most consumed oil in the world and plant diseases are a major factor limiting production. As a way to control this disease is usual the use of fungicides. However, is increasing search for natural products that provide less risk to the health of the applicator and the end consumer, beside reduce environmental pollution and the selection of resistant strains. This work aimed to evaluate the potential of essential oils of lemongrass and rosemary in resistance induction and management of powdery mildewsoybean, as well as the physiological responses of culture. Essential oils of lemongrass and rosemary (1000, 2000, 4000 and 8000 üL L?¹), acibenzolar-S-methyl, fungicide controlwere studied. Two experiments were developed, the first evaluating the essential oils under the induction of resistance in sorghum and bean seedlings. Sorghum mesocotyls and bean hypocotyls were treated with essential oils, submitted in conditions of defense compounds synthesisand evaluated phytoalexin and peroxidase activities. In the second experiment the essential oils were applied in soybean growth stages in V9, R1, R2 and R3 and evaluated the severity of powdery mildew as well as the enzymatic activity, production factors and physiological factors of culture under such conditions. Essential oils of lemongrass and rosemary have the ability to induce resistance in sorghum and beans, and the essential oil of lemon grass activates the metabolism of phytoalexins in both cultures and the essential oil of rosemary active peroxidases in beans. The essential oils of lemongrass and rosemary interfere in the management of soybean powdery mildew, and the essential oil of lemon grass reduces powdery mildew AACPD. Both interfere with physiological responses and resistance mechanisms of the culture, demonstrating yet be specific as to the concentration and mode of action.