Bacillus sp., fertilization forms, and salt stress on soybean production

ABSTRACT The use of Bacillus sp. mitigates salt stress and increases the productive yield in soybean plants. In this context, the objective of the present study was to evaluate the production of soybean grown under different forms of fertilization and salt stress, inoculated with Bacillus sp. The experiment was performed in the experimental area of the University of International Integration of Afro-Brazilian Lusophony (UNILAB), Redenção, Ceará, Brazil. A completely randomized design was used in a 4 x 2 x 2 factorial scheme, with five replications, corresponding to four forms of fertilization (F1 = 100% of the NPK recommendation; F2 = 50% of the NPK recommendation; F3 = 100% bovine biofertilizer; F4 = organomineral fertilization - 50% NPK + 50% bovine biofertilizer), two electrical conductivities of the irrigation water (ECw - 0.3 and 4.0 dS m-1), with and without inoculation of Bacillus sp. The forms of fertilization organic with 100% of the recommendation through bovine biofertilizer, organomineral fertilization - 50% mineral and 50% organic with bovine biofertilizer, and 50% of the NPK recommendation promote greater productive performance of the soybean crop irrigated with water of lower salinity. Organomineral fertilization - 50% mineral and 50% organic with bovine biofertilizer was more efficient for soybean production, in the absence or presence of Bacillus sp. Salt stress negatively affected the production components of soybean crop under all forms of fertilization. RESUMO O uso de Bacillus sp. atenua o estresse salino e aumenta o rendimento produtivo em plantas de soja. Neste contexto, o objetivo do presente estudo foi avaliar a produção da soja cultivada sob diferentes formas de adubação e estresse salino, inoculada com Bacillus sp. O experimento foi realizado na área experimental da Universidade da Integração Internacional da Lusofonia Afro-Brasileira (UNILAB), Redenção, Ceará. Utilizou-se um delineamento inteiramente casualizado em esquema fatorial 4 x 2 x 2, com cinco repetições, correspondente a quatro formas de adubação (F1 = 100% da recomendação de NPK; F2 = 50% da recomendação de NPK; F3 = 100% de biofertilizante bovino; F4 = organomineral - 50% de NPK + 50% de biofertilizante bovino), duas condutividades elétricas da água de irrigação (CEa - 0,3 e 4,0 dS m-1), com e sem inoculação de Bacillus sp. As formas de adubação orgânica com 100% da recomendação através de biofertilizante bovino, adubação organomineral - 50% mineral e 50% orgânica co