Application of Bacillus spp. Phosphate-Solubilizing Bacteria Improves Common Bean Production Compared to Conventional Fertilization

Abstract

The use of phosphate-solubilizing bacteria (PSB) can be a sustainable strategy to increase phosphorus availability and promote satisfactory crop yields. The objective of this study was to evaluate whether inoculation with PSB in common bean increases (i) growth, (ii) nutrition, (iii) yield, and (iv) grain quality, and (v) reduces the chemical phosphorus application dose to obtain maximum yields. The experiment was conducted in an Oxisol using a randomized block design in a 4 × 4 factorial scheme, with four replicates, using the cultivar IAC 2051. The first factor was four doses of P₂O₅ (0, 20, 40 and 60 kg ha^-1), and the second factor was four doses of PSB (0, 100, 200 and 300 mL ha^-1). For leaf area and leaf chlorophyll content, the association of PSB inoculation with a P₂O₅ dose of 40 kg ha^-1 promoted the best conditions for the common bean. P₂O₅ application increased yield by 79 kg ha^-1 for each 10 kg ha^-1 added. PSB inoculation at a dose of 192 mL ha^-1 promoted P export of 15.3 kg ha^-1, and the PSB dose of 159 mL ha^-1 increased yield by 389 kg ha^-1 (12%) compared to the control. Grain quality remained within the standards required by the consumer market, being little affected by the treatments. Improvements in common bean growth and nutritional and physiological status promoted by P₂O₅ application and PSB were essential in increasing yield, so these are sustainable production strategies.

Keywords: Bacillus megaterium; Bacillus subtilis; Phaseolus vulgaris L.; phosphorus; sustainability.

Figure 1

P content in leaves (PCL, (A)), dry matter (PCDM, (B)) and grains (PCG, (C)) of common bean as a function of P₂O₅ doses.

Figure 2

P content in the dry matter (PCDM, (A)), P accumulation in the dry matter (PADM, (B)) and P export (C) by common beans as a function of phosphate-solubilizing bacteria (PSB).

Figure 3

Decomposition of the interaction between P₂O₅ doses and phosphate solubilizing bacteria (PSB) doses for chlorophyll a (Chl a, (A,B)), chlorophyll b (Chl b, (C,D)) and carotenoids (Cx + c, (E,F)) in common bean plants in the vegetative stage (V4).

Figure 4

Chlorophyll a (Chl a, (A)), chlorophyll b (Chl b, (B)) and chlorophyll total (Chl total, (C)) in common bean plants in stage R8 as a function of P₂O₅ doses.

Figure 5

Chlorophyll content index (CCI) in common bean plants as a function of P₂O₅ doses.

Figure 6

Interactions between P₂O₅ doses (A) and phosphate-solubilizing bacteria doses (PSB, (B)) for leaf area (LA) of common beans.

Figure 7

Number of pods per plant (NPP, (A)) and number of grains per pod (NGP, (B)) as a function of phosphate-solubilizing bacteria (PSB) doses.

Figure 8

Dry matter (DM, (A,B)) and yield (YLD, (C,D)) of common bean plants as a function of P₂O₅ doses and phosphate-solubilizing bacteria (PSB) doses.

Figure 9

Principal component analysis for spatialization of treatments and variables in two dimensions (biplot). PC: principal component; P: P₂O₅ doses; PSB: phosphate-solubilizing bacteria; YLD: grain yield; NPP: number of pods per plant; NGP: number of grains per pod; HGW: hundred-grain weight; DM: aerial part dry matter; CCI: chlorophyll content index; Chl total: total chlorophyll content in the leaves; PCL: P content in the leaves; PCG: P content in the grains.