Inoculação do feijão-caupi com estirpes de alfa e beta-rizóbios nativas de solos do semiárido

Abstract

Chemical fertilization can have negative effects on the environment and on the financial sustainability of crops, so it is important to seek alternative ways of supplying nutrients, with emphasis on biological nitrogen fixation (BNF). Thus, this work aims to evaluate the development and productivity of cowpea (Vigna unguiculata (L.) Walp.) inoculated with alpha and beta-rhizobia strains native to semiarid soils. The study was carried out in the experimental area and laboratories of the Serra Talhada Academic Unit (UAST), belonging to the Federal Rural University of Pernambuco (UFRPE). Two experiments were carried out, one for the symbiotic efficiency of the isolates and the other for agronomic evaluation in the field. In the first experiment, a completely randomized design was adopted, with 3 replications, being evaluated 17 isolates of beta-rhizobia and 18 of alpha-rhizobia, and in the second, a randomized block design was adopted, with 4 replications, being evaluated 2 strains of beta-rhizobia. and 2 of alpha-rhizobia selected in the previous test. For both experiments, the control treatments inoculation with the recommended strain (BR 3267), application of nitrogen fertilizer (80 kg.ha -1) and the treatment without inoculation and without nitrogen fertilizer (absolute control) were added. At the end of each experiment, biometric parameters, nodulation, N and CP content, efficiencies and productivity were evaluated. Data were submitted to analysis of variance, using RStudio software, and means compared by Tukey's test at 5% probability. In the symbiotic efficiency test phase, the alpha and beta-rhizobia strains showed promising as inoculants for cowpea due to their results equal or superior to the registered strains and also to the nitrogen fertilizer. For the agronomic performance phase of the inoculated cowpea, four strains were chosen, two of alpha-rhizobia C98-3 (Azorhizobium caulinodans) and C78-2 (Bradyrhizobium japonicum), and two of beta-rhizobia C60-2 (Paraburkholderia sabee). and C33-4/1 (Paraburkholderia sabee) because they have the highest averages and originate from the semi-arid region of the sertão. In the agronomic performance phase of cowpea inoculated with alpha-rhizobium strains C78-2 (Bradyrhizobium japonicum) it stood out from the other treatments in all the proposed parameters and the alpha-rhizobium strain C98-3 (Azorhizobium caulinodans) also stood out in relation to to productivity. It is concluded that the alpha-rhizobium C78-2 and alpha-rhizobium C98-3 strains can be recommended for the production of specific inoculants for cowpea.