Aplicação boratada em diferentes estádios fenológicos na cultura do girassol

Abstract

Due to its varied use as fodder for animal feed, vegetal oil for human consumption and still a promising source for biodiesel production, the sunflower becomes an important crop for the country's economy and consequently is chosen by the producers due to its demand. Thus, the present work had as objective to evaluate the application of boron doses in different phenological stages of the sunflower crop. The experiment was carried out in the interimharvest of 2017 and 2018 at the Universidade Estadual de Goiás, Câmpus Ipameri, located in the municipality of Ipameri-GO. The experimental design was a randomized block design, arranged in a 2 x 5 x 6 factorial scheme, with four replications. The first factor with five levels refers to the phenological stages of application of boron (V0, V6, V18, R1 and R3), the second factor with six levels refers to the doses of boron (0, 1, 2, 3, 4 and 5 kg ha-1 ), applied by soil using boric acid as the source of boric acid (17%). The following evaluations were carried out for each crop: leaf boron concentration, relative chlorophyll index, plant height, stem diameter, chapter diameter, chapter mass, number of grains per chapter, mass of 1000 grains and productivity. The data of boron concentration foliare productivity were submitted to analysis of variance evaluated separately for each year and the averages compared by the Tukey test to 5% probability for the phenological stages and for the other variables the data were submitted to analysis of joint variance and the means compared by the Tukey test at 5% probability for year of cultivation and application times, and for the B doses regression analysis was performed for all variables. The phenological stages of boron application did not influence the parameters evaluated in the sunflower crop. The use of doses between 3.38 and 3.74 kg ha-1 of boron influenced the characteristics of leaf boron concentration, plant height and mass of a thousand grains. And most of the evaluated parameters were influenced by the year of cultivation.