Resposta de genótipos de soja quanto ao uso de ácido húmico

Abstract

Brazil is the world's largest producer and exporter of soybean, which are essential for the country's and the world's food security. The use of humic acid, which has benefits for the soil and plants, and the use of efficient genotypes in the use of nutrients can contribute to the sustainable intensification of agriculture. Thus, the objective of this research was to evaluate the effect of humic acid on soybean cultivars under laboratory and field conditions. In the laboratory, four doses of humic acid (0, 5, 10 and 15 L ha-1) and six soybean cultivars (BRS FAVORITA RR, BRS VALIOSA RR, BRSGO 7560, TMG 801, UFUS 6901 and UFUS 7101) were evaluated in a 4 x 6 factorial scheme and randomized block design with five replications. The experimental plot consisted of a roll of germitest paper with 50 seeds, kept in a germinator at 25 ºC and photoperiod of 12 hours of light for six days. It was possible to conclude that: 1) soybean cultivars influence all the characteristics evaluated in germination and initial growth of the seedlings, except the percentage of damaged seedlings and hard seeds; 2) the dose of 5 L ha-1 of humic acid provides an increase in the percentage of germination and high vigor seedlings and a reduction in the percentage of abnormal and deformed seedlings, as well as greater length and accumulation of fresh matter of the aerial part and total of the seedlings and; 3) the cultivars show different behavior as a function of humic acid doses for the percentage of deteriorated seedlings, root length and fresh matter, dry matter accumulation and root/shoot ratio. In the field, two doses of humic acid (0 and 15 L ha-1) and six soybean cultivars (BRS FAVORITA RR, BRS VALIOSA RR, NS 6906 IPRO, TMG 801, UFUS 6901 and UFUS 7101) were evaluated in a 2 x 6 factorial scheme and a randomized block design with four replications. The experiment was carried out in Uberlândia-MG, during the 2019-2020 harvest, in soil classified as Red Latosol, of sandy loam texture. It was possible to conclude that: 1) the development of soybean plants and SPAD index at R5 stage, as well as the agronomic and production-related characteristics differ among the six soybean cultivars, with UFUS 6901 and TMG 801 being the most productive and; 2) the application of 15 L ha-1 of humic acid in the sowing furrow does not improve the development and production of soybean cultivars, therefore, it is not possible to differ the cultivars regarding the efficiency in the use of nutrients.