Response of common bean to Rhizobium reinoculation in topdressing

Abstract

The response capacity of the bean to fix atmospheric nitrogen is questionable, mainly due to its inability to supply all the nitrogen in the flowering and grain filling phases when the crop needs it most. Thus, a new application of inoculant can keep the population of rhizobia in the soil at adequate levels, meeting all the nitrogen demands of the plant. This study aimed to investigate the nodulation capacity and the production of beans submitted to doses and reinoculation of Rhizobium in topdressing under field conditions in two growth stages. For this, an experiment was conducted using a randomized block design with four replicates in a 4 × 2 + 2 factorial scheme. The treatments consisted of the application of four doses of liquid inoculant containing Rhizobium tropici (SEMIA 4088), in the concentration 2 × 109 CFU g-1, in topdressing (0, 100, 200 and 400 mL ha-1), in two development stages (V4 and R5) of plants, and two additional treatments (inoculation via seed at a dose of 100 g of the product per 50 kg of seeds and mineral nitrogen fertilization at a dose of 16 kg ha-1 applied at sowing and 60 kg ha-1 in topdressing, divided into two stages, with half being applied at the stage V3 and the other half in V4 stage).The inoculant application increased the nodulation rates of bean cultivar BRS Cometa and the dry biomass produced by plants, using doses of 232 and 221 mL ha-1, respectively. The dose of 257mL ha-1 of the liquid inoculant applied in topdressing at the V4 stage, and the inoculation via seed provide greater common bean yield without supplementing mineral nitrogen.

Effectiveness of Rhizobium tropici sp. Strain UD5 Peat Biofertilizer Inoculant on Growth, Yield, and Nitrogen Concentration of Common Bean

“…In another study, Rhizobium inoculation increased the nodulation of bean cultivar BRS Cometa and the dry biomass when supplied at 232 and 221 mL ha −1 , respectively. Inoculating with 257 mL ha −1 of the liquid-based inoculant in topdressing during the V4 stage and on seeds, the latter approach showed markedly greater yield of common bean established without the addition of inorganic nitrogen fertilizer [25].…”

Reinoculation in Topdressing of Rhizobium tropici, Azospirillum brasilense, and the Micronutrients Mo/Co in Common Bean

“…Recently, some research results have been unanimous in stating that the reinoculation procedure with R. tropici in the common bean crop, conducted close to flowering, promotes the reinvigoration of the fixative activity of the population of bacteria inoculated at sowing [39][40][41]49]. In this study, it can be noted that the morphological and agronomic analyzes obtained similar results, but with the inclusion of other products in the application, such as A. brasilense in association with Mo/Co, which ensured the achievement of high levels of grain yield, equivalent to the use of mineral nitrogen source.…”

“…Premature aging of the population of nodulating bacteria associated with environmental stress can cause nodular senescence and cessation of N 2 fixation of legumes generally coinciding with the flowering and filling stage of grains [36,37], phases in which precisely the demand for nutrients, water, and photoassimilates by the plant is greater. In addition, nodules that appear late with the advancement of the crop cycle can contribute in a restricted way to crop nutrition and increase yield [38,39]. In this way, the reinoculation in topdressing made directly in the soil can renew the rhizobian population effectively in incorporating N 2 [39,40], associating the application of A. brasilense [41] and the Mo/Co micronutrients, exactly in a phase in which the bean crop has a greater nutritional demand.…”

“…In addition, nodules that appear late with the advancement of the crop cycle can contribute in a restricted way to crop nutrition and increase yield [38,39]. In this way, the reinoculation in topdressing made directly in the soil can renew the rhizobian population effectively in incorporating N 2 [39,40], associating the application of A. brasilense [41] and the Mo/Co micronutrients, exactly in a phase in which the bean crop has a greater nutritional demand. However, the effect of the association of these products applied to bean cultivation is little investigated by scientific research.…”