Produtividade da soja em função de fontes de boro em solos de diferentes texturas

Abstract

Sources of boron (B) applied via foliar can have different effects depending on soil texture, thus affecting soybean metabolism and productivity due to the importance of this element for the crop. Generally, its content is low in tropical soil, which can cause deficiencies and reduced soybean productivity. Therefore, each crop needs an adequate supply of B. The research hypothesis was that different sources of B applied via spraying to the soil and soybean leaves are influenced by soil texture. Therefore, the research aimed to evaluate the foliar application of different B sources, and their effects on root production, gas exchange, SPAD index, water use efficiency, and soybean productivity. The experimental design used was a 2×5 factorial with five replications. Two soil textures Dystrophic Red Latosol (LVd) with clayey texture and Dystrophic Tb Haplic Cambisol (CXbd) with medium texture × five boron sources (control, borotec1, borotec2, octaborate, and boric acid) applied via spraying on the soil, on the leaves in reproductive stage R1 and soybean desiccation. During the research, root volume, plant dry mass (root, stem, and leaf), gas exchange, water use efficiency, and productivity were evaluated. We conclude with the research that applying boron sources promotes an increase in root volume, root dry mass, leaf area index, SPAD index, node number, and soybean productivity for average soil texture (CXbd). The medium-textured soil responded positively to the application of B sources. The grain production in the pod followed the increasing order of 50% for 3 grains>40% for 2 grains>10% for 1 grain>10% for 4 grains. To classify grain diameter on sieves depending on boron sources and soil texture, the order of grain diameter on sieves was 15 (5.9 mm)>14 (5.5 mm)>16 (6.3 mm)>17 (6.7mm). For the dry mass of the stem and 1000 grains, the clayey soil texture (LVd) was superior regardless of the B sources used. The borotec2 foliar fertilizer promoted greater leaf production in soybeans regardless of the soil texture used. The borotec1 foliar fertilizer promoted greater pod production with 4 grains in both soil textures. For the number of aborted pods, the boric acid source promoted greater abortion regardless of the textures used