<b>Di-nitrogen fixation at the early and late growth stages of soybean

Abstract

Soybean derives a significant portion of the required nitrogen (N) from the symbiosis with rhizobia bacteria. However, information on the available genetic variation for N 2 fixation capacity in different growth stages of soybean is limited. The objective of this study was to investigate the N 2 fixation capacity of 22 soybean lines compared with that of non-nodulating and supernodulating checks at the early and late growth stages and identify the most informative traits for selection. Two cycles of greenhouse experiments were carried out to estimate the percentage of N derived from the atmosphere (%Ndfa) as well as 10 different traits related to N 2 fixation. The results showed that %Ndfa was significantly different among the lines at the early and late growth stages. SPAD readings showed the highest correlation with the early N 2 fixation, whereas shoot dry weight with the late N 2 fixation. Early and late %Ndfa could be used to select superior lines for N 2 fixation and study the underlying physiological and molecular mechanism.Fixação de nitrogênio na fase inicial e final de desenvolvimento da soja RESUMO. Na soja uma parcela significativa do nitrogênio (N) requerido deriva de sua simbiose com a bactéria do gênero rhizóbio. No entanto, informações sobre variabilidade genética disponível para a capacidade de fixação de N 2 em diferentes estádios fenológicos é limitada. O objetivo deste estudo foi investigar a capacidade de fixação de N 2 durante a fase inicial e final de desenvolvimento de 22 genótipos de soja comparada a de genótipos não nodulantes e supernodulante utilizados como testemunhas, e também identificar os caracteres mais informativos para fins de seleção. Dois ciclos de experimentos foram conduzidos em casa de vegetação para estimar o percentual de N derivado da atmosfera (%Ndda), assim como outros 10 caracteres relacionados a fixação de N 2 . Os resultados demonstraram que o %Ndda foi significativamente diferente entre os genótipos nas duas avaliações. Leituras de fotossíntese com SPAD apresentaram a maior correlação com a avaliação inicial de fixação de N 2 , enquanto que a massa seca da parte aérea demonstrou a mais alta correlação com a avaliação de fixação de N 2 na fase final de desenvolvimento. Avaliações do %Ndda nas fases inicial e final de desenvolvimento da cultura podem ser utilizadas para seleção de genótipos superiores de soja para fixação de N 2 , assim como para o estudo dos mecanismos de controle nos âmbitos fisiológico e molecular. Palavras-chave: Glycine Max; %Ndda; técnica de diluição do nitrogênio-15; nodulação; simbiose.

Genotype and cytokinin effects on soybean yield and biological nitrogen fixation across soil temperatures

“…Although nodule size has been suggested to influence BNF more than other nodule traits (de Araujo et al, 2017; Tajima et al, 2007; Voisin, Salon, Jeudy, & Warembourg, 2003b), contrarily greater fixation was seen in DM50I17 with smaller nodules than DM40R16. We confirm a genotypic effect on the timing of BNF (Hamawaki & Kantartzi, 2018) and additionally show this occurs for nodulation; however, nodulation and the timing of BNF were not correlated (Tables 3 and 4). Low RZT delays BNF and nodule formation (Zhang et al, 1995) in both genotypes (Tables 3 and 4) and therefore does not explain differences in N supply across sowing dates.…”

Inoculation of rhizobia increases lima bean (Phaseolus lunatus) yield in soils from Piauí and Ceará states, Brazil

“…Indeed, UFPI59 contributed for increasing the N content in lima bean and it can be correlated to the higher nodule size found with this strain. There is a strong correlation between nodule size and N accumulation in plants (Deliae et al, 2010;Voisin et al, 2015;Hamawaki & Kantartzi, 2018) and it corroborates with the results observed in this study. It can indicate that UFPI59 presents high effectiveness in contributing with N to lima bean.…”

Growth, Yield and Nutritional Performance of Sweet Sorghum and Legumes in Sole and Intercropping Influenced by Type of Legume, Nitrogen Level and Air Quality

“…Doubled plant population of mungbean and lower intra-row spacing between sweet sorghum and mungbean have aggravated the competitive ability between sweet sorghum and mungbeanand thus led to a reduction of growth and yield parameters. Sweet sorghum would have been non-competitive and cooperative with soybean as it hasa greater ability to fix atmospheric nitrogen (range of 56-89 % of total plant N) compared to mungbean (45-76% of total plant N) and being able to make available a part of such N to associated plants [42]. The LAI, plant height and grain yield of intercropped sweet sorghum were significantly decreased by 10.5, 8.4, and 8.5 %, respectively, when N dose was reduced to 30 kg ha -1 compared to 60 kg ha -1 .…”