Mitigação do estresse biótico e abiótico em mudas de bananeira por bactérias

Abstract

Stresses from both biotic and abiotic causes are extremely harmful to plants as they delay vegetative development and, consequently, limit agricultural production. The banana crop is highly water demanding and susceptible to phytosanitary problems, such as Fusarium wilt. With this, beneficial microorganisms have been used and positive effects in the mitigation of these stresses have been observed. In this sense, the present study aimed to evaluate, through two experiments, the effect of the application of beneficial microorganisms in mitigating the effects of water deficit on the growth of banana seedlings and in inducing resistance to Fusarium wilt. Micropropagated ‘Prata Catarina’ banana seedlings were transplanted into tubes and acclimatized for a period of 60 days. Subsequently, the seedlings were transplanted into pots of 30 dm3 (1st experiment) and 3 dm3 (2nd experiment) containing a mixture of subsoil + sand (1:1). In the first experiment, a 4 x 5 factorial was established with four levels of irrigation and five doses of a commercial bioinoculant based on Azospirillum brasilense. The second experiment was set up in the split root system with 12 treatments consisting of 10 endophytic bacteria and two controls. The results with A. brasilense showed that its application in combination with the highest level of irrigation promoted increments of 31.4% and 9.7% for the variables root volume and number of leaves, respectively. The dose range between 0.79 mL and 1.8 mL can be considered the most efficient to promote increment. In the test with endophytes, it was observed that among the isolates EB127 (Sporolactobacillus sp.), EB68 (Bacillus safensis), EB49 (Bacillus licheniformis), EB169 (Bacillus pumilus) and EB37 (Bacillus sp.) were considered the most efficient in inducing resistance in plants, as they provided reductions in symptom severity greater than 60%.