Ação do herbicida alachlor na microbiota do solo, nodulação e rendimento de plantas de amendoim

Abstract

The present study aimed at evaluating the effect of alachlor in nodulation and yield of two peanut genotypes, as well the population of bacteria and fungi and microbiotic activity of the soil under field conditions. The experimental design was the  randomized blocks in a factorial scheme (2x4x4). The experiment was carried out with two peanut genotypes (“Vagem Lisa” – G1, and “Tatuí” – G2) and four treatments: hoeing + inoculated seed (H + IS), hoeing + non- inoculated seed (H + NIS), herbicide +  inoculated seed (HE + IS), herbicide + non-inoculated seed (HE + NIS), with four replicates and 32 plots. The alachlor herbicide was applied in the ground cover at a dose of 6 L ha-1 of the commercial product.  Sowing was carried out in experimental plots of 17,5 m2
and data were collected 42  and 56 days after emergence in order to determine the number and dry mass  of nodules. Grain yield and quantification of fungi and bacteria were determined 84 days after emergence. Microbiotic activity was monitored every fifteen days, during 84 days. The rhizobium (Bradyrhizobium japonicum)
introduced was not efficient to compete with the indigenous population in the nodulation process. The presence of herbicide increases the population of bacteria and the soil microbial
activity. Compared to the “Vagem Lisa” genotype, the “Tatuí” genotype presented superior yield only in the treatment of herbicide + inoculated seed.