INFLUENCE OF DIAZOTROPHIC BACTERIA ON ARBUSCULAR MYCORRHIZAL FUNGI IN RHIZOSPHERE OF CAJANUS CAJAN

Abstract

CAJANUS CAJAN IS A SUMMER LEGUME WITH SEMI-PERENNIAL CYCLE. ITS STRONGEST FEATURE IS THE AGGRESSIVE AND ROBUST ROOT SYSTEM THAT REACHES DEEP INTO THE SOIL. IT IS RUSTIC AND GROWS WELL IN LOW-FERTILITY SOILS, BEING A MAJOR PRODUCER OF BIOMASS AND NITROGEN FIXING. THE EXPERIMENT WAS CONDUCTED AT THE AGRICULTURAL MICROBIOLOGY LABORATORY OF THE EVANGELICAL SCHOOL OF GOIAN�SIA-GO. THE EXPERIMENTAL DESIGN WAS ENTIRELY RANDOMIZED ARRANGED IN TWO TREATMENTS, BEING ONE INOCULATING DIAZOTROPHS (RHIZOBIUM TROPICI AND AZOSPIRILLUM BRASILENSE) AND A TREATMENT WITHOUT APPLICATION, WITH FOUR REPLICATIONS. FOR THE LABORATORY TESTS, 50 CM�³ OF RHIZOSPHERE SOIL WERE TAKEN WITH ROOTS DURING THE FLOWERING PERIOD. TO DETERMINE THE PERCENTAGE OF COLONIZATION, THE ROOTS WERE CLARIFIED AND STAINED WITH 0.05% TRYPAN BLUE-LACTOGLYCEROL AND THE EVALUATION WAS MADE IN A STEREOMICROSCOPE, FOLLOWING THE PROCEDURE OF THE INTERSECTION OF QUADRANTS. AMF SPORES WERE EXTRACTED BY WET SIEVING METHOD FOLLOWED BY CENTRIFUGATION IN 50% SUCROSE. THE IDENTIFICATION OF THE GENERA OF ARBUSCULAR MYCORRHIZAL FUNGI WERE CARRIED OUT FROM THE MORPHOLOGICAL CHARACTERISTICS OF SPORES ON SLIDES WITH PURE POLYVINYL LACTO-GLYCEROL AND MIXED WITH MELZER REAGENT AND CLASSIFIED ACCORDING TO THE INTERNATIONAL CULTURE COLLECTION OF ARBUSCULAR AND VESICULAR-ARBUSCULAR MYCORRHIZAL FUNGI. THE SPORE DENSITY VALUES WERE HIGHER IN THE TREATMENTS WITHOUT APPLICATION OF NITROGEN FIXING BACTERIA WHEN COMPARED WITH THE TREATMENT WITH APPLICATION. INOCULATION OF DIAZOTROPHIC BACTERIA CAUSED NO STATISTICAL DIFFERENCES BETWEEN TREATMENTS REGARDING THE MYCORRHIZAL COLONIZATION RATES. THE GENERA DIVERSISPORA SP. AND SCROBICULATA SP. WERE FOUND EXCLUSIVELY IN THE TREATMENT NON-INOCULATED WITH DIAZOTROPHS. ON THE OTHER HAND, THE GENERA CLAREIDOGLOMUS SP. AND SCUTELLOSPORA SP. WERE THE ONLY IDENTIFIED IN SAMPLES WITH THE INOCULATION OF NITROGEN-FIXING BACTERIA. ACAULOSPORA SP., SCLEROCYSTIS SP., GLOMUS SP. AND GIGASPORA SPP. WERE PRESENT IN BOTH SAMPLES.