Do rates of humic acid influence on soybean seed germination and seedlings establishment?

Abstract

The objective was to evaluate the effect of humic acid doses on seed germination and seedling initial growth in soybean. At the Seed Analysis Laboratory of the Federal University of Uberlândia, 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 × 6 factorial scheme. A randomized block design was adopted with five replications. Each plot consisted of a roll of germitest paper with 50 seeds. The rolls were kept in a germinator, at 25 ºC and 12 hours of light for six days. After the evaluation, it was verified that the soybean cultivars significantly affect all the characteristics evaluated in germination and initial growth of the seedlings, except the percentage of damaged seedlings and hard seeds. Regardless of the cultivar, 5 L ha^-1 of humic acid provides a higher percentage of germination and high vigor seedlings; lower total percentage of abnormal seedlings and those classified as deformed; as well as greater length and accumulation of fresh matter of the aerial part and total of the seedlings. However, for the percentage of deteriorated seedlings, root length and fresh matter, dry matter accumulation, and root/shoot ratio, soybean cultivars show different behavior as a function of humic acid doses. Therefore, considering the action of humic acid on the performance of the genetic material allows maximizing resource efficiency and ensuring superior results in soybean cultivation.