BACTÉRIAS PROMOTORAS DO CRESCIMENTO VEGETAL NA GERMINAÇÃO E CRESCIMENTO VEGETATIVO DA CULTURA DO MILHO

Abstract

Associative bacteria are versatile in promoting plant growth as they are able to fix nitro-gen, synthesize phytohormones, solubilize nutrients, and increase plant tolerance to bio-tic and abiotic stresses. In this sense, this paper aimed to evaluate the vegetative growth of green corn with different doses of mineral Nitrogen (N) and Azospirillum brasilense, and to evaluate the chemical treatment and inoculation with Azospirillum brasilense, Bacillus subtilis, Bacillus amyloliquefaciens, and Priestia aryabhattai in the germination of corn seeds. Two experiments were carried out being: (a) (A) Randomized block de-sign with 20 treatments, 4 replicates, and 4 blocks, arranged in a 2x2x5 factorial scheme; commercial inoculant Biomax® Azum (AbV5) in seed treatment, control without inocu-lation, two contrasting water conditions (irrigated and water suppression), and five dos-es of N (0, 40, 80, 120 e 160 kg ha-1) were applied. The data were subjected to quadratic regression analysis, at a 5% probability level and ANOVA; (b) (B) completely random-ized design arranged in a 2x5 factorial scheme with 2 chemical seed treatments (with and without) and 5 inoculants as Bacillus subtilis, Priestia aryabhattai, Bacillus amylo-liquefaciens, Azospirillum brasilense and control without inoculation were applied. Each treatment consisted of two hundred seeds, one of which was carried out in the laborato-ry and the other one in a seedbed with sand. It was found in (A) that the application of N at 120 kg ha-1 dose enabled the greatest result for plant height, root dry mass and vol-ume, and root fresh mass at 90 days after emergence (DAE). The number of living leaves, number of total leaves, plant height, root volume, total chlorophyll, and leaf tem-perature are higher in treatments without water suppression. In (B), it was found that the inoculation of corn seeds with the A. brasilense and P. aryabhattai bacteria together with the control treatment provided greater length of the seedling aerial and root parts in laboratory. The B. subtilis and P. aryabhattai bacteria associated with seeds without chemical treatment provided greater root dry mass. Inoculation with A. brasilense pro-vided greater germination, greater number of leaves, root volume, and seedling corn height in the test in a seebed with sand, not differing statistically from the control, while P. aryabhattai showed greater germination for the seedling height and number of leaves variables. The A. brasilense inoculation in seeds treated with fungicides and insecticides provided greater root dry mass associated with greater root volume. It is concluded that A. brasilense, B. subtilis, and P. aryabhattai bacteria promote significant increases in the germination and initial growth of corn seedlings.