Response of common bean to Rhizobium reinoculation in topdressing

Itamar R Teixeira,Westefann S Sousa,Gisele C Da S Teixeira,Paulo R Lopes

doi:10.1590/1807-1929/agriambi.v26n4p274-282

Itamar R Teixeira, Westefann S Sousa + Show 2 more

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https://doi.org/10.1590/1807-1929/agriambi.v26n4p274-282

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Abstract

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.

Highlights

The biological nitrogen fixation (BNF) is predominant in plants belonging to the Fabaceae family, like beans, providing a good amount of N necessary for the satisfactory development of the plants if a set of fully functional nodules is available during the plant cycle
As for the inoculant doses factor, applied in topdressing besides the seed inoculation, a significant difference was observed for the number of nodules (NN), nodule dry mass (NDM), BIO, leaf dry mass (LDM), dry mass of each pod (DMEP), number of grains per pod (NGPP) and YIELD
The data referring to the regression analysis for the number of nodules per plant (NN) and nodule dry mass (NDM) fitted to a quadratic polynomial regression (Figure 2); the estimated doses of 224 and 232mL ha-1 of the inoculant resulted in the maximum point of NN (Figure 2A) and NDM (Figure 2B) with values of 101.89 units per plant and 0.25 g per plant, respectively

Summary

Introduction

The biological nitrogen fixation (BNF) is predominant in plants belonging to the Fabaceae family, like beans, providing a good amount of N necessary for the satisfactory development of the plants if a set of fully functional nodules is available during the plant cycle. The initial formation of nodules is critical for common bean crops, beginning between 15 and 20 days after sowing (Araújo et al, 1996). In this sense, thepresence of nodules that makes available N2 throughout the plant growth cycle may represent a key strategy to provide the nutrient N required by the common bean, contributing to yield gains (Moretti et al, 2018; Zhou et al, 2021), which can be achieved with the reinoculation in topdressing to the flowering stage. One of the limitations of rhizobia reinoculation in the bean is the lack of scientific studies on the issue

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