Do the application forms and doses of boron affect wheat crops?/As formas de aplicanao e as doses de boro afetam a cultura do trigo?

Boron is one of the most limiting micronutrients in the grain production system in Brazil. Thus, the objective of this study was to evaluate the effects of the application forms and doses of boron on the concentration of this nutrient in the leaves, straw, and grains of wheat, as well as the production components and grain yield. The residual effect of boron in the soil was also evaluated. An experiment was conducted in a no-tillage system in Oxisol with clay texture in Selviria, Mato Grosso do Sul. The experimental design was a randomized block design with four replicates arranged in a 4 x 3 factorial scheme. Four doses of boron (0, 1, 2, and 4 kg [ha.sup.-1]) were applied with a boric acid source (B = 17%) and three application forms: a) during the desiccation of the predecessor straw with herbicide; b) at the time of sowing in soil along with formulated fertilization seeding, and c) via the leaves with the application of post-emergent herbicide. The application of boron to the soil at the time of sowing at an approximate dose of 2 kg [ha.sup.-1] provides the highest number of spikelets per ear and wheat grain yield. Key words: Triticum aestivum borated fertilization boron time application boron concentration in aerial part grain yield O boro e um dos micronutrientes que mais limita a produtividade de graos do sistema produtivo no Brasil. Desta forma, objetivou-se avaliar o efeito de formas de aplicacao e doses de boro na concentrando deste nutriente na folha diagnose, palhada e graos de trigo, componentes produtivos e produtividade de graos, bem como o efeito residual de B no solo. O experimento foi realizado em Selviria, MS, em sistema plantio direto em um Latossolo Vermelho distrofico, textura argilosa. O delineamento experimental foi em blocos ao acaso com quatro repeticoes, dispostas em esquema fatorial 4 x 3, com quatro doses de boro (0, 1, 2 e 4 kg [ha.sup.-1]) na forma de acido borico (B = 17%); e tres formas de aplicacao: a) na dessecacao da palhada antecessora, juntamente com o herbicida; b) no momento da semeadura, no solo juntamente com a adubanao de semeadura e c) via foliar, junto com a aplicacao do herbicida pos-emergente. A aplicacao de B ao solo no momento da semeadura na dose aproximada de 2 kg [ha.sup.-1] propiciou o maior numero de espiguetas por espiga e produtividade de graos de trigo. Palavras-chave: Triticum aestivum adubacao boratada momento da aplicando de boro concentrando de boro em parte aerea produtividade de graos