A INOCULAÇÃO DE FUNGOS ENDOFÍTICOS NO CONTROLE DA SEVERIDADE DA RAMULOSE EM PLANTAS DE Gossypium hirsutum

Abstract

Phytopathogenic microorganisms such as Colletotrichum gossypii var. can attack Gossypium hirsutum plants during their development, compromising their physiological potential. As rhizospheric and endophytic microorganisms compete with phytopathogens for ecological niches, avoiding the hypothesis that symbiotic fungi to the Butia purpurascens palm tree, endemic to the cerrado, could be used in the protection of cotton plants, in an attempt to epheriosites selectors the reducing effects of ramulosis caused by the spoilage fungus Colletotrichum gossypii var. on the adult plant. To test this hypothesis, plants resulting from inoculation with four symbiotic fungi, selected from antibiosis tests previously performed in vitro, were evaluated. Seeds infested by Colletotrichum gossypii var. and associated with endophytic fungi, were grown mixed in soil and previously autoclaved, in a vase system, in a greenhouse. Estimates were performed at the vegetative phenological stage of cotton, evaluating biometric growth traits, including dry and fresh biomass, synthesis of photosynthetic pigments, photosynthetic patterns and chlorophyll a fluorescence. The data obtained were examined by analysis of variance and mean tests to verify the effect of inoculation of endophytic fungi on the control of the phytopathogen Colletotrichum gossypii var, observing the deleterious effects of ramulose on growth and maintenance of plant characteristics. In general, the endophytic Hamigera inseticola (BP33EF) showed better performance to control the physiological severity of the symptoms of ramulosis induced by Colletotrichum gossypii in cotton plants, inducing the highest accumulation of dry and fresh biomass, photochemical performance above the verifice and control plants higher rates of photochemical stress. Plants inoculated with the endophytic BP328EF = Codinaeopsis sp., however, tended to show higher means for photosynthetic rate (A), stomatal conductance (gsw) and transpiration (E), indicating a relative improvement in the photosynthetic capacity of the plants in relation to the control . The results obtained in this work will stimulate new studies about the endemic Cerrado endophytes, opening perspectives for future applications in the total control of cotton ramulose.