Combinação de rizobactérias e doses de nitrogênio no controle de Meloidogyne javanica em feijoeiro

Abstract

The bean crop has great socio-economic importance in Brazil and its production is limited, among other factors, the parasitism of nematodes of the Meloidogyne genre. Tactical control alternatives have been researched and these deserve mention the use of rhizobacteria and nitrogen fertilization. The rhizobacterias, besides control pathogen, they are also involved in the promoting of the plant growth, such as the ability to fix atmospheric nitrogen. The study aimed to evaluate Rhizobacteria Combination and doses of nitrogen in the Meloidogyne javanica control on bean plant. The study was conducted in a greenhouse at Unimontes Janaúba campus. The treatments were arranged in randomized blocks, in factorial arrangement 5 x 5 + 1, with five doses of N (0, 25, 50, 100 e 200 kg.ha¹) and five isolates: Bacillus pumilus-1, Bacillus subtilis-34, Bacillus sp.-36, Bacilluspumilus-60 e Bacillus pumilus-76+1 control (non-inoculated seeds, cultivated in infested soil with M. javanica without nitrogen). Bean plants, derived from microbiolized seeds with the isolated and maintained in pots with sterilized soil were inoculated with 3,000 eggs of M. javanica. After 60 days of the inoculation were evaluated the vegetative characteristics of the bean plant and the nematodes. It was significant interaction between the isolated x doses of urea. In each combination, the greatest reductions in the number of egg masses in relation to the control were 54,68%, 62.50%, 66,8%, 84,6% e 83,17% for the treatments Bacillus pumillus-60 on the 0 dose, B. subtilis-34 on the 25 kg.ha dose, B. pumillus-1 on the 50 kg. ha dose, B. subtilis-34 on the 100 kg.ha dose and B. pumillus-lon the 200 kg.ha dose, respectively. For a variable number of galls, the greatest reductions were 57,0% for B. pumillus-60 on the 0 dose and 69,04% for Bacillus sp.-36 on the 25 kg.ha dose. For the isolates B. pumilus-1, Bacillus sp.-36 and B. pumilus-76, there was a linear reduction in the number of egg masses and galls in response to increasing doses of nitrogen. The seed inoculation with isolates of Bacillus spp. associated to nitrogen fertilization contributes to the reduction of egg masses and galls M. javanica in the bean plant root. At 0 dose, the isolates B. pumillus-60 and B. pumillus-76 reduced the number of egg masses and galls in the absence of urea indicating nematicide effect. There was no offect of the treatments on J2 and vegetative characteristics.