Differences in Nodulation and Grain Yield on Common Bean Cultivars with Different Growth Cycles

The common bean can obtain nitrogen (N) from the decomposition of the soil organic matter, mineral fertilizers, and biological nitrogen fixation (BNF). This study aimed to evaluate the behavior of nodulation parameters related to BNF throughout the development of common bean cultivars with different growth cycles. The experiments were conducted for two consecutive years (2012 and 2013) with 22 common bean cultivars with different growth cycles. The common bean cultivars were inoculated with a mixture of Rhizobium tropici strains (SEMIA 4077, SEMIA 4080, and SEMIA 4088). In 2012, samplings were performed from the V4 to the R8 stage, and the parameters related to nodulation and crop growth were evaluated at each stage and in the R9 stage, the grain yield and its components were measured. For the 2013 experiment, the same evaluations were performed but the nodulation parameters were only measured in the R6 and the R7 stages. Differences in the number and activity of the nodules along the development of the cultivars were observed. For the early and semi-early cycle cultivars, the activity of the nodules was observed until the R7 stage, while for the regular and late cycle cultivars, this activity only occurred until the R6 stage, resulting in three more days of nodule activity for the early and semi-early cycle cultivars as compared to the regular and late ones. The number of nodules correlated significantly with the shoot dry weight and the shoot Total-N; while the nodules dry mass showed a significantly high correlation with both parameters. The overall mean grain yield was 2,766.75 kg ha(-1). However significant difference related solely to the various cultivars cycles were not observed.