Feijão caupi submetido à inoculação combinada de rizóbio em solo de cerrado

Abstract

Biological nitrogen fixation is an alternative to the use of nitrogen fertilizers in agriculture. This study aimed to evaluate the development and the productive characteristics of cowpea subjected to combined inoculation rhizobia in Cerrado soil. The experiment was conducted in the experimental field at the Federal University of Mato Grosso, campus Rondonópolis, from December 2014 to March 2015. We used a randomized block design, with ten treatments, that consisted of inoculation of strains MT8, MT15 and MT16, isolated from cowpea, the BR3267 strain (recommended for cowpea), the combinations MT8+MT15, MT8+MT16, M15+MT16 and MT8+MT15+MT16, a witness with nitrogen fertilization (70 kg N ha-1) and one without inoculation and without the addition of nitrogen, in three repetitions, totaling thirty plots. The first assessment took place 40 days after sowing they were the parameters evaluated: plant height, dry matter accumulation (shoot, root, and total), the relative efficiency of the strains, the number and dry weight of nodules and the Falker chlorophyll index at the 40 and 60 days after sowing. After harvesting, carried out 70 days after sowing, evaluated the number of pods per plant, number of seeds per pod, length of the pods, grain yield, concentration and accumulation of nitrogen in grain and crude protein in the grain. Data was submitted to ANOVA and Tukey tests and orthogonal contrasts by F test, both 5% probability using the statistical program SISVAR. Combined inoculation of the strains MT8+MT15+MT16 influenced positively the shoot dry weight, roots dry weight and total dry weight of cowpea plants. Similarly, combined inoculation MT8+MT15 enabled get as the number of pods per plant. The Falker chlorophyll index at the 60 days was affected by the combined inoculation MT8+MT15, as well as by MT15 strain when inoculated isolated. There was the influence of combinations MT8+MT15, MT8+MT16 and MT15+MT16 on the grain yield. Developmental characteristics and productivity of cowpea were influenced by the combination of rhizobia inoculation.