Dry Matter, Grain Yield, and Yield Components of Dry Bean as Influenced by Nitrogen Fertilization and Rhizobia

Abstract

Abstract Dry bean is an important legume crop for a large portion of the world's population. Nitrogen (N) is one of the most yield-limiting nutrients in all dry bean–producing regions of the world. A greenhouse experiment was conducted to evaluate responses of 15 dry bean genotypes to N fertilization with and without rhizobial inoculation grown on a lowland soil locally known as Varzea. Nitrogen treatments were (i) 0 mg N kg−1 (control or N0), (ii) 0 mg N kg−1 + inoculation with rhizobial strains (N1), (iii) inoculation with rhizobial strains + 50 mg N kg−1 (N2), and (vi) 200 mg N kg−1 (N3). Shoot dry weight, grain yield, yield components, maximum root length, and root dry weight were significantly affected by N fertilization, rhizobial inoculation, and genotype treatments. The N × genotypes interactions were significant for shoot dry weight, grain yield, number of pods per plant, number of grain per pod, 100-grain weight, grain harvest index (GHI), and maximum root length and root dry weight. These significant interactions indicate that genotypes performance varied with varying N rates and inoculation treatments. Maximum grain yield was produced at 200 mg N kg−1 treatment. Inoculation with rhizobial strains improved grain yield but did not reach the level of 200 mg N kg−1 applied with chemical fertilizer. Based on grain yield efficiency index, genotypes were classified as efficient, moderately efficient, and inefficient in N-use efficiency. Overall, the most efficient genotypes were BRS Pontal, Diamante Negro, BRS Grafite, BRS Requinte, and BRS 9435 Cometa, and inefficient genotypes were BRSMG Talisma and Aporé. Keywords: Grain harvest indexgrain yield efficiency indexPhaseolus vulgarisroot dry weightroot length Acknowledgment Financial support for this research was provided by the Brazilian Scientific and Technological Research Council (CNPq) Grant No. 471032/2010-7.