Microbiolização de sementes de maracujazeiro amarelo para controle de Fusarium spp.

Abstract

The yellow passion fruit (Passiflora edulis Sims.) is of great socioeconomic importance to Brazil due to the commercial demand for its fruit in various market sectors and the generation of employment and income. However, it suffers from several diseases such as Fusarium wilt, caused by the fungus Fusarium oxysporum f. sp. passiflorae (Fop), which significantly reduces production. The main control methods consist of cultural and genetic methods, making it necessary to search for new alternatives. In this context, biological control emerges as a promising and sustainable alternative. Therefore, the objective of this work was to evaluate the efficiency of commercial products based on Bacillus spp. and Trichoderma spp. for the control of Fusarium spp. in vitro and in vivo by treating passion fruit seeds and to analyze their influence on the physiological and morphological attributes of the plant. The experiment was carried out in the Phytopathology Laboratory of the Federal University of Paraíba, Campus II, Areia-PB. The treatments used were: T1- (ADE), T2- BT-Turbo Max® (1.33 mL/200 mL), T3- Bioimune® (5.33 mL/200 mL), T4- Biobaci® (2.67 mL/200 mL), T5- Trichoturbo® (0.00267 mL/200 mL), T6- Trichoagro® (1.87 g/200 mL). The in vitro control was performed by cultivating Fusarium spp. in potato-dextrose-agar (PDA) culture medium supplemented with the treatments. The variables analyzed were colony diameter, mycelial growth inhibition, area under the mycelial growth curve, spore production, and percentage of spore inhibition. In vivo control was performed by treating yellow passion fruit seeds with the treatments described above, sowing them in 1.5L pots with substrate in a greenhouse 24 hours after treatment application. On the 31st day after sowing, inoculation was carried out using the "half-moon" method with a spore suspension. On the 30th day after inoculation, the following variables were evaluated: infection rate, biometric analyses such as shoot and root length, stem diameter, root volume, root and shoot dry mass, and physiological analyses such as Falker chlorophyll a, b and total indices, chlorophyll a fluorescence with the variables initial fluorescence (F0), maximum fluorescence (Fm) and quantum efficiency of photosystem II (Fv/Fm), gas exchange with the variables: CO2 assimilation rate (A), stomatal conductance (gs), internal CO2 concentration (Ci), transpiration (E), instantaneous water use efficiency (WUE), intrinsic water use efficiency (IWUE) and instantaneous carboxylation efficiency (ICE). In the in vitro control, all treatments were effective in reducing the analyzed variables, with Trichoagro® being the most efficient. In in vivo control, the Bio-imune® treatment showed greater efficiency among all those used by promoting pathogen control as well as preservation of chlorophyll a and total chlorophyll levels and biometric variables.