Abstract

Cowpea culture is spreading in the Brazilian Cerrado Region and specifically in Mato Grosso State. To evaluate the productive characteristics of cowpea inoculated with rhizobia lineages and grown in the Cerrado of Mato Grosso State, we conducted an experiment in a randomized block design with seven treatments, which consisted of five rhizobia lineages. Four lineages were previously isolated from cowpea (MT08, MT15, MT16 and MT23); one was a recommended lineage for cowpea in Brazil (BR3267). Two controls were included: one was equivalent to 75 kg N ha^-1 nitrogen and another was without nitrogen fertilization and without inoculation of rhizobia lineage. They were arranged in six blocks totaling 42 parts of 12.5 m² each. At 40 days after sowing (d.a.s.), six plants of ​​each part of floor area were collected to determine the variables plant height, dry mass of shoots and roots, total dry mass, number of nodules, dry mass of nodules, SPAD reading and relative efficiency of each lineage. Data were subjected to analysis of variance using the statistical analysis program SISVAR. To compare the means, it was evaluated with Tukey test at 5% probability and contrast analysis. Regarding the lineage used, the most satisfactory result for plant height was BR3267 lineage; however, there were statistical differences between treatments with nitrogen fertilization. There were significant differences between dry weight of shoots, total dry weight and dry weight of nodules. The BR3267 lineage presented better results in the dry mass of roots and for relative efficiency. The most satisfactory results for SPAD readings and number of nodules were observed in MT15 lineage. The BR3267 and MT15 lineages tested and analyzed had high symbiotic effectiveness for inoculation in cowpea.

Key words: Vigna unguiculata, rhizobium, nitrogen fixation.