Comparison of the allocation of phytomass in soybean and bean and its potential role in biological nitrogen fixation

Abstract

Soybean is a self-sufficient specie in nitrogen acquisition due to their efficient association with diazotrophs. Unlike bean, which requires nitrogen supplementation, soybean is not dependent on nitrogen fertilization. This interspecies difference may be related to the allocation pattern of photosynthates during their growth cycles. Distinct from soybean, common bean cannot maintain their active nodules until the end of their growth cycle due to the unavailability of photosynthates in their roots after flowering. To compare the partitioning of the phytomass in soybean (Glycine max (L.) Merrill) and common bean (Phaseolus vulgaris L.) species during their ontogenetic cycles, a growth analysis experiment were conducted with Favorita BRS and BRS Pontal varieties, respectively. The results revealed that soybeans keep producing leaves, branches and roots even after flowering, indicating no limitation in the supply of photosynthates to its organs, especially to the roots, where a predominant allocation of photosynthates can favor nodule activity. After flowering in bean plants, allocation preferentially occurs to the pods at the expense of the other organs including the roots, which potentially affects their nodule activity.Alocação comparada de fitomassa em soja e feijão e possível controle na fixação biológica do nitrogênio RESUMO. A eficiente associação com bactérias diazotróficas faz da soja uma espécie auto-suficiente na obtenção do nitrogênio que necessita, tornando-a não dependente de adubação nitrogenada, diferentemente do feijão que carece da aplicação do nutriente na forma de fertilizantes. Presume-se que esta diferença interespecífica possa ter relação com o padrão de alocação de fotossintatos ao longo dos ciclos das leguminosas, de maneira que, ao contrário da soja, o feijão não consegue manter os seus nódulos ativos, até o final do seu ciclo, pela indisponibilidade de fotossintatos nas raízes após o florescimento. Para comparar a partição de fitomassa nas espécies soja (Glycine max (L.) Merrill) e feijão (Phaseolus vulgaris L.) ao longo dos seus ciclos ontogenéticos foi conduzido um experimento de análise de crescimento com as variedades BRS Favorita e BRS Pontal, respectivamente. Os resultados obtidos indicam que a soja continua produzindo folhas, ramos e raízes, mesmo após a floração, indicando não limitação por fotossintatos no abastecimento de seus órgãos, com predomínio da alocação para as raízes, o que pode favorecer a atividade dos seus nódulos. Nos feijoeiros, após a floração, ocorre alocação preferencial para as vagens em detrimento dos demais órgãos, como as raízes, o que pode afetar a atividade nos seus nódulos.Palavras chave: análise de crescimento, atividade de nódulos, fitomassa, Glycine max, Phaseolus vulgaris, Rhizobium. 286 Portes and Araújo

Perennial, but not annual legumes synergistically benefit from infection with arbuscular mycorrhizal fungi and rhizobia: a meta‐analysis

“…If reinvestment of gain from one symbiont into the complementary symbiont is necessary for realization of synergism, then there may be an additional lag in realization of this benefit. Annual legumes can have very short life‐spans and investment in roots can be reduced with initiation of flowering (Portes & Araújo, 2012 ), when plants begin preferentially allocating carbon to flower and fruit production, potentially reducing the opportunity to realize synergism compared to perennial legumes.…”

Variability of root traits in common bean genotypes at different levels of phosphorus supply and ontogenetic stages

“…Araújo & Teixeira (2008), in two field experiments, observed that the grain yield of common bean cultivars did not correlate with shoot mass exhibited at the flowering or pod setting stages, whereas grain yield correlated with shoot mass at the beginning of the pod filling and mid-pod filling stages, concluding that the yield potential of different common bean cultivars is not intrinsically associated with the vegetative vigor at flowering. The nutrient budget of common bean cultivars grown in the field also demonstrated that acquisition of N and P during early pod-filling is rather significant in fulfilling seed demand, whereas during late pod-filling, nutrient remobilization within the plant assumes more relevance to the crop budget (Araújo et al, 2012). Therefore, genotypic selection for improved growth and nutrient acquisition within common bean cultivars should be performed preferentially during the early pod-filling stages, in which the growth and yield potentials of a specific genotype are likely to be fully expressed.…”

“…Portes & Araújo (2012), comparing common bean and soybean in terms of biomass allocation among plant tissues, noticed that during reproductive stages bean plants invested preferentially in pod growth in detriment to the root system and other vegetative organs. Notably, genotypes of groups II and III showed much more intense growth of basal and lateral roots between the two times of harvest than the genotypes of groups I and IV (Table 3).…”

Morphophysiology, Productivity and Quality of Soybean (Glycine max (L.) Merr.) cv. Merlin in Response to Row Spacing and Seeding Systems

“…Soybeans are a valuable source of protein and oil, containing essential free amino acids and fatty acids, as well as other nutrients such as isoflavones, phytosterols and saponins (isoflavone, phytosterol, and saponins) [3,4]. Cultivation of soybean plants does not require large doses of nitrogen, which is possible thanks to the symbiosis of those plants with nodule bacteria (Bradyrhizobium japonicum) present in the root nodules, assimilating atmospheric nitrogen (N 2 ) [5,6]. The productivity of soybeans is determined by the interactions between the selection of the appropriate genotype of a cultivar and the environment and the Agronomy 2021, 11, 403 2 of 18 method of cultivation of that species [7].…”