Response of horticultural crops to application of bioprotector and biological control of Ralstonia wilt in Brazilian Ultisol

Abstract

The production of biofertilizers from rocks is an economic process that increases nutrients for plant nutrition and reduces environmental pollution. The aim of the study was to evaluate the effectiveness of the bioprotector from phosphate and potassium rocks mixed with an earthworm compound inoculated with free-living diazotrophic bacteria (Beijerinckia indica) and fungus containing chitosan (Cunninghamella elegans) on the characteristics of tomatoes, peppers and green peppers inoculated and non-inoculated with the wilt bacteria Ralstonia solanacearum. The fertilization treatments were: bioprotector applied at the 50% recommended rate - RR (NPKP50), 100% RR (NPKP100) and 150% RR (NPKP150); soluble fertilizers applied alone at the recommended rate RR (NPKF100), with antibiotic (NPKF100+ant) and with crustaceous chitosan (NPKF100+C). A control treatment with earthworm compound (20 t ha-1) was used for comparative purposes. The best results for all horticultural plants were obtained with the bioprotector (NPKP) applied at the highest rate (150% RR) and with the soluble fertilizer (NPKF) at the recommended rate for plants not inoculated with Ralstonia solanacearum. With regard to the effect of the bioprotector in the control of Ralstonia solanacearum, a different response for the horticultural crops with peppers revealed normal growth when inoculated with the pathogenic bacteria, and all of the tomato plants with soluble fertilizer alone died after pathogen addition. Soluble fertilizer with the addition of antibiotic and crustaceous chitosan protected green peppers and peppers against R. solanacearum, particularly when using chitosan. The bioprotector (NPKP) appears to be an alternative to soluble fertilizer.