Increase in yield, leaf nutrient, and profitability of soybean co-inoculated with Bacillus strains and Arbuscular mycorrhizal fungi

ABSTRACT Microorganisms in the soil and rhizosphere can release part of the total phosphorus in the soil through solubilization, mineralization, and an increase of the root absorption surface. The ability of phosphate solubilizing bacteria and mycorrhizal fungi to promote higher yield and profitability in co-inoculated soybean was investigated. For this purpose, field and greenhouse experiments were conducted in the years 2020 and 2021 in Brazil. In the field, the first factor was composed of microorganism application on soybean (simple inoculation with Bradyrhizobium; co-inoculation with Bacillus strains; co-inoculation with arbuscular mycorrhiza), and the second factor consisted of the application or not of phosphate fertilizer (0 and 100 kg ha-1 of P2O5). In the greenhouse, treatments of the first factor were maintained with 50 % of the phosphate fertilization and one treatment added (standard inoculation with 100 % of the fertilization). Plant growth, roots, nodules, leaf nutrition, yield, and profitability were evaluated. In 2020, co-inoculation increased plant height, the number of pods, grains, and profitability index. The co-inoculation with Bacillus strains and arbuscular mycorrhiza promoted yield increase only associated with phosphate fertilization, by 813 and 761 kg ha-1 compared to standard inoculation, respectively. In 2021, there were increases for pods, grains, yield, gross profit, net income, and profitability index. Co-inoculation with Bacillus strains and arbuscular mycorrhiza promoted increased soybean yield and profitability, confirming itself as a sustainable technology for Brazilian soybean fields.

摘要：土壤与根际微生物可通过溶解、矿化作用以及扩大根系吸收表面积，活化土壤中部分总磷。本研究探究了溶磷细菌与菌根真菌共接种对大豆增产及收益提升的效果。为此，研究团队于2020年与2021年在巴西开展了田间与温室试验。田间试验设置双因子处理：第一因子为大豆微生物接种方案，包括单接种慢生根瘤菌（Bradyrhizobium）、共接种芽孢杆菌（Bacillus）菌株、共接种丛枝菌根（arbuscular mycorrhiza）；第二因子为磷肥施用水平，设置不施磷肥与施100 kg·ha⁻¹ P₂O₅两个梯度。温室试验保留了施加50%磷肥的第一因子处理组，并新增了施加100%磷肥的标准接种处理组。试验测定指标涵盖植株生长、根系性状、根瘤特征、叶片营养水平、产量及收益性。2020年试验结果显示，共接种可提升大豆植株株高、荚果数、籽粒数及收益指数。仅在配施磷肥的条件下，芽孢杆菌菌株与丛枝菌根的共接种分别较标准接种增产813 kg·ha⁻¹与761 kg·ha⁻¹。2021年试验中，共接种可显著提升大豆荚果数、籽粒数、产量、毛利润、净利润及收益指数。芽孢杆菌菌株与丛枝菌根的共接种可有效提升大豆产量与收益性，证实该技术可作为巴西大豆田的可持续种植技术。