Abstract
The biological effects of humic substances on vegetables depend on the source of extraction and the concentration used, on the vegetable species and on the age of the plant. This study aimed to evaluate the effect of different humic acid (HA) doses extracted from vermicompost on the germination and initial growth of Brachiaria brizantha cv. MG5. To that end, germination tests were conducted in germination agents, as well as emergence test in greenhouse and seedlings growth test for those agents. For all these tests, five doses of HA [0.0; 1.0; 2.0; 4.0 e 8.0 mM C.L-1] were used, with and without reapplying HA. The following characteristics were analyzed: percentage of germination, percentage of normal seedlings in the first counting of the germination test, percentage of abnormal seedlings, percentage of non-germinated seedlings, percentage of emergence, emergence speed rates, fresh and dry matter of the upper and roots part, length of the upper and roots part and number of lateral roots. Positive effect of HA reapplication in the percentage of abnormal seedlings was observed. With increasing doses of HA, there was a reduction in the percentage of germination and normal seedlings in the first count. The application of HA promoted increase in shoot length and number of lateral root. There was no significant difference in the length of the root. Humus acid affects positively the initial growth of B. brizantha cv. MG5, with the best stimulation being observed when the 2.0 mM C.L-1 dose was applied. Key words: Forage, Urochloa sp., vigor.
Highlights
Organic matter for soils, waters and sediments have humic substances as their main component
The great majority of the biostimulating effects of humus acid (HA) has been credited to its similar activities to the auxins (Chen and Aviad, 1990; Canellas et al, 2002; Façanha et al, 2002), considering that these effects on the vegetable growth depend on the type of source from where the humic substances are isolated, on the type and age of the plants and on the concentration used for the essays (Kononova, 1982; Santos and Camargo, 1999; Muscolo et al, 2013; Martinez-Balmori et al, 2014)
MG5 plants, related to the used dose and to the reapplication of the solution, we aimed to evaluate the effect of different doses of humus acid extracted from vermicompost on the germination and initial growth of B. brizantha cv
Summary
Organic matter for soils, waters and sediments have humic substances as their main component. They influence chemical, physical and biological properties and directly affect the growth and metabolism of plants, especially the root system (Nardi et al, 2002). The great majority of the biostimulating effects of humus acid (HA) has been credited to its similar activities to the auxins (Chen and Aviad, 1990; Canellas et al, 2002; Façanha et al, 2002), considering that these effects on the vegetable growth depend on the type of source from where the humic substances are isolated, on the type and age of the plants and on the concentration used for the essays (Kononova, 1982; Santos and Camargo, 1999; Muscolo et al, 2013; Martinez-Balmori et al, 2014)
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