Do the application forms and doses of boron affect wheat crops?

ABSTRACT 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 Selvíria, 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-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-1 provides the highest number of spikelets per ear and wheat grain yield.

摘要 硼（Boron）是巴西谷物生产体系中最为关键的限制性微量营养元素之一。为此，本研究旨在评估硼的不同施用方式与施用量对小麦叶片、秸秆及籽粒中该营养元素含量的影响，同时探究其对小麦产量构成要素与籽粒产量的作用，并同步测定硼在土壤中的残留效应。试验于巴西南马托格罗索州塞尔维里亚（Selvíria）的黏质氧化土（Oxisol）免耕耕作系统（no-tillage system）中开展。试验采用随机区组设计（randomized block design），设置4×3因子式试验方案，共设4次重复。供试肥料为硼含量17%的硼酸源（boric acid source），设置4个硼施用量梯度（0、1、2、4 kg ha⁻¹），并采用3种施用方式：a）与除草剂一同对前茬秸秆进行脱绿处理时施用；b）播种时结合播种施肥作业施入土壤；c）结合苗后除草剂（post-emergent herbicide）喷施进行叶面施用。研究结果显示，在播种时以约2 kg ha⁻¹的施用量将硼施入土壤，可获得最高的每穗小穗数与小麦籽粒产量。