Differents ways of applying Azospirillum brasilense in common bean crops

Abstract

Bean plants can have their development stimulated through association with bacteria that promote plant growth, such as bacteria of the genus Azospirillum. However, the form of application and the dose of bacterial inoculant used can interfere with the results. The objective of the work was to verify the influence of the form of application, foliar or seed, of different doses of Azospirillum, on the development of carioca beans. An experiment was conducted in a greenhouse, covered with transparent plastic, and surrounded by shade netting, belonging to the Federal University of Mato Grosso, Sinop Campus. The soil was collected from the subsoil in the UFMT/ Sinop forest reserve, (Dystrophic Dark Red Oxisol, 20-40 cm layer). The soil was air-dried, sieved through a 4 mm sieve and autoclaved (40 minutes at 121ºAtm). Liming and fertilization were carried out based on soil fertility analysis. ANfc9 carioca bean seeds were used for sowing. The treatments consisted of different doses of Azospirillum brasilense (commercial liquid inoculant containing the Ab-V5 strain with a concentration of 1x10⁸ UFC/mL), with applications being carried out on the seeds in the sowing and foliar route at vegetative stage V3. Consisting of the following treatments: T1 - Inoculation in the seed (0 mL/25 kg of seed); T2 - Inoculation via foliar in V3 (0 mL/25 kg of seed); T3 - Inoculation into the seed (250 mL/25 kg of seed); T4 - Inoculation via foliar in V3 (250 mL/25 kg of seed); T5 - Inoculation into the seed (500 mL/25 kg of seed); T6 - Inoculation via foliar in V3 (500 mL/25 kg of seed); T7 - Inoculation into the seed (750 mL/25 kg of seed); T8 - Inoculation via foliar in V3 (750 mL/25 kg of seed); T9 - Inoculation into the seed (1000 mL/25 kg of seed); T10 - Inoculation via foliar in V3 (1000 mL/25 kg of seed). The experimental design was randomized blocks (DBC) with 10 treatments with 4 blocks. The chlorophyll content was evaluated at 13, 34 and 40 days after sowing. The experiment was carried out until the beginning of the reproductive period (stage R5), when the plants were collected and evaluated: stem diameter, plant height, internode length, leaf area and dry mass accumulation of the aerial part. and the root. The method of inoculant application did not interfere with plant development. The dry mass of the aerial part was positively influenced by the increase in the dose of inoculant containing Azospirillum brasilense applied to bean plants.