Promoção de crescimento e potencial de indução de resistência em tomateiro à mancha-alvo mediadas por rizobactérias

Abstract

The use of rhizobacteria to increase crop productivity by promoting growth and management of the target spot through the induction of systemic resistance to plant diseases are shown as tool capable of allowing the expansion of tomato North region. Thus, the objectives of this work were to evaluate the influence of biochar in the population of cultivable soil bacteria, besides the root colonization capacity of bacterial isolates, growth promotion, phosphate solubilization, indole acetic acid production and induction of resistance to Corynespora almost. The influence of the isolates origin on the mentioned variables was also evaluated. As well as the identification of the bacterial isolates. The influence of the bio-carbon on the population of cultivable soil bacteria was carried out using the colony-forming unit counting methodology. Verification of root colonization was performed using techniques for visualizing turbidity zones in tubes with agar-water (0.8%), optical microscopy and root plating. Growth promotion and induction of resistance were evaluated in greenhouse and the experimental design adopted for both experiments was completely randomized and inoculation of the bacteria was performed by microbiolization. Identification was performed by sequencing the 16S rRNA gene. The results indicate that doses up to 34 t ha-1 positively influence the population of cultivable soil bacteria in the 0-10 cm layer. The three methods used to evaluate root colonization were efficient and complement each other in the interpretation of the results. The isolates ISO4T2, ISO22T3, ISO53T1, ISO17T3 and ISO113T1 promoted an increment in the confirmation test and present potential to be evaluated in the field in the future. Isolates 7T1, 114T1 and 52T2 induced partial resistance against C. cassiicola and present potential to be evaluated under field conditions. The origin of the isolates has influence on the ability to colonize the root system of tomato plants and solubilize phosphate, but does not affect the other variables. The partial sequencing of the 16S rRNA gene allowed the identification of 23 isolates at the genus and group level, but not in species.