CARACTERIZAÇÃO E SELEÇÃO DE RIZÓBIOS NATIVOS ASSOCIADOS À Vigna unguiculata (L.) Walp.

Abstract

The cowpea Vigna unguiculata (L.) Walp., commonly known as macassar and feijão de corda, this beanis the main subsistence crop of these regions, with more importance in the northeastern Sertão. However, the practiced cultivations in the state use low technological level. In this way, we need applications of industrialized mineral inputs, which contributes to the yield increase. With that, the use of biological inputs that can replace industrialized chemicals has been increasingly frequent in agriculture.The cowpea is able to establish symbiosis and nodulate with several species of bacteria of the rhizobia group, including genera such as Azorhizobium, Burkholderia, Bradyrhizobium, Mesorhizobium, Rhizobium, Sinorhizobium.With this low specificity of the crop in relation to the microsymbionte, it is a limiting factor to the exploitation of this technology, considering that the nodulating bacteria present in the soil, besides being competitive and being in greater numbers, present a variable efficiency in the FBN. For this reason it is important to study strategies that can evaluate the composition and distribution of rhizobia strains native to the soil where it is intendedto apply the inoculant. Based on that, the objective of this study was to select isolates of native rhizobia from agricultural soils of the city of Areia (PB), for cowpea plants, and to characterize and evaluate the rhizobia isolates obtained, comparing to the recommended strain 03-84 -6/2010 UFLA. The tests were carried out in a protected environment of the DSER. After 40 days, according to the obtained results, it could be found that all treatments presented nodules, except the second replication of the treatment without nitrogen. Eight different groups of native rhizobia were obtained. It can be concluded that the humid zone of Caatinga in Areia-PB, has native nitrifying bacteria able to nodulate and fix nitrogen. However, there is lack of study of these microorganisms, highlighting the importance of more researches such as these, in Paraíba.