Influência dos inseticidas cipermetrina e metomil no desenvolvimento e promoção de crescimento vegetal das bactérias Burkholderia sp. UAGC867 e Pseudomonas sp. UAGC97

Abstract

Bacteria Plant Growth Promoting (BPGP) has been studied as environmental remediation, as many agricultural soils are contaminated by residue of pesticides. Among these bacteria are Burkholderia and Pseudomonas, which have the ability to grow in different environments, having the ability to conserve the environment through their activity to biodegrade polluting compounds. Thus, the objective of this study was to evaluate the potential of tolerance and degradation of bacteria Burkholderia sp. UAGC867 and Pseudomonas sp. UAGC97, in relation to the cypermethrin and methomyl insecticides, used to control Spodoptera frugiperda; the respirometric rate ground when influenced with the cypermethrin insecticide and bacterial strains; the effect of cypermethrin on the indole acetic acid production by BPGP and the influence of bacterial inoculation with cypermethrin in corn seeds. For the tolerance test inrelation to cypermethrin and methomyl insecticide , the strains UAGC867 and UAGC97 were cultivated in mineral liquid medium plus glucose and each treatment received 25-50-100 and 200 mg L-1 of each insecticide. The treatment control was free insecticide. Tha degradation test of insecticides by bacteria followed the same methodology, differing only in the absence of glucose treatments. The influence of bacterial inoculum and concentrations different of cypermethrin (0-25-50-100-200 mg L-1) in the soil, the experiment was conducted in microcosms installed in a greenhouse, and later collected 100 g ground and transferred to pots in order to evaluate the respiration rate of the soil in the laboratory. It was also evaluated the production of indole acetic acid (IAA) by PBPG, through the influence of cypermethrin insecticide in the field concentration. Finally, the strains Burkholderia sp. UAGC867 and Pseudomonas sp. UAGC97 were cultured in the presence and absence of cypermethrin (100 mg L-1) to evaluate the germination and growth of corn seed. The two bacteria evaluated were able to express growth in the presence of pesticides concentrations, demonstrating their tolerance for the same. Burkholderia sp. UAGC867 was able to degrade all methomyl concentrations, and 25 mg L-1 of the insecticide cypermethrin. Pseudomonas sp. UAGC97 exhibited degradation only in 25 mg L-1 methomyl insecticide. There carbon dioxide captured oscillations throughout the experiment, however, was not observed between treatments unclustering by principal component analysis. The IAA synthesis by BPGP was not inhibited by the insecticide cypermethrin, however, there was prominent production by Pseudomonas sp. UAGC97 on the seventh day of evaluation. There was no statistical difference between treatments evaluated in the germination speed index and the germination percentage. The assessments of plant growth promotion revealed that the cultivation of Burkholderia sp. UAGC867 in the presence of 100 mg L-1 cypermethrin stimulated the growth of shoots of corn seedlings, in addition to presenting significant results in fresh and shoot dry. The evaluated bacteria exhibit promoting characteristics of plant growth, with potential for more exploration of their interaction with the plant.