Solubilizadores de fósforo na promoção do crescimento, incidência de grãos ardidos e produtividade da soja

Abstract

(Glycine max (L.) Merrill) cultivation in Brazil is often constrained by nutritional limitations and foliar diseases, leading to significant yield losses. To address these issues, integrated management strategies such as seed treatment with phosphorus-solubilizing microorganisms and foliar fungicide application have gained prominence. This study aimed to evaluate the effects of different phosphorus solubilizers and fungicide application regimes on the growth, nutritional status, and yield of soybeans in western Paraná, Brazil. The experiment was conducted at the experimental area of the Federal University of Technology - Paraná (UTFPR), Campus Santa Helena-PR. A randomized block design was used in a split-plot scheme with four replications, in a 5 × 2 factorial arrangement. The main plots consisted of five seed treatments: 1) control (no inoculant); 2) Azospirillum brasilense, Pseudomonas fluorescens, and Bacillus megaterium (GreenPhos®); 3) Bacillus aryabhattai (Valentia®); 4) Bacillus amyloliquefaciens (Duobac Meta®); and 5) Trichoderma harzianum (Trincheira®). The subplots consisted of two foliar treatments: a) control (no fungicide) and b) four applications of the fungicide Cronnos® (picoxystrobin + tebuconazole + mancozeb) at 2 L ha⁻¹. At 30 days after emergence (DAE), growth variables (plant height, root length and volume, leaf area, and shoot and root dry mass) were assessed. At the R2 stage, the third fully developed trifoliate was collected for leaf nutrient analysis. At physiological maturity, yield components (number of pods per plant, number of grains per pod, and 1000-grain weight) were determined, and grain damage incidence was assessed. Grain yield was determined by harvesting the central rows of each plot and correcting to 13% moisture. Data were subjected to analysis of variance and means compared by Tukey’s test (p ≤ 0.05). Multivariate relationships were explored using principal component analysis (PCA). Seed treatment with Bacillus amyloliquefaciens (Duobac Meta®) promoted the highest initial growth metrics and, in combination with fungicide application, resulted in the highest grain yield (approximately 3,600 kg ha⁻¹) and the lowest percentage of damaged grains. PCA confirmed the strong positive association between Bacillus amyloliquefaciens inoculation and both growth and yield variables. It is concluded that seed inoculation with Bacillus amyloliquefaciens is an effective strategy to enhance soybean development and grain yield, particularly when integrated with a foliar fungicide program.