Seeds enriched with phosphorus and molybdenum improve the contribution of biological nitrogen fixation to common bean as estimated by 15n isotope dilution

Abstract

SUMMARYSeeds with a high concentration of P or Mo can improve the growth and N accumulation of the common bean (Phaseolus vulgaris L.), but the effect of enriched seeds on biological N 2 fixation has not been established yet. This study aimed to evaluate the effect of seeds enriched with P and Mo on growth and biological N 2 fixation of the common bean by the 15 N isotope dilution technique. An experiment was carried out in pots in a 2 x 3 x 2 x 2 factorial design in randomized blocks with four replications, comprising two levels of soil applied P (0 and 80 mg kg -1 ), three N sources (without N, inoculated with rhizobia, and mineral N), two seed P concentrations (low and high), and two seed Mo concentrations (low and high). Non-nodulating bean and sorghum were used as non-fixing crops. The substrate was 5.0 kg of a Red Latosol (Oxisol) previously enriched with 15 N and mixed with 5.0 kg of sand. Plants were harvested 41 days after emergence. Seeds with high P concentration increased the growth and N in shoots, particularly in inoculated plants at lower applied P levels. Inoculated plants raised from high P seeds showed improved nodulation at both soil P levels. Higher soil P levels increased the percentage of N derived from the atmosphere (%Ndfa) in bean leaves. Inoculation with the selected strains increased the %Ndfa. High seed P increased the %Ndfa in inoculated plants at lower soil P levels. High seed Mo increased the %Ndfa at lower soil P levels in plants that did not receive inoculation or mineral N. It is concluded that high seed P concentration increases the growth, N accumulation RESUMO: SEMENTES ENRIQUECIDAS COM FÓSFORO E MOLIBDÊNIO

Grain yield of common bean (Phaseolus vulgaris L.) varieties is markedly increased by rhizobial inoculation and phosphorus application in Ethiopia

“…The application of P to bean plants also resulted in decreased shoot δ 15 N values, an indication of higher N 2 fixation (Table 3 ) and this agrees with the findings of Chagas et al ( 2010 ). However, there was a positive synergistic effect of Rhizobium inoculation and P-fertilisation on plant growth and symbiotic performance, as indicated by the lower shoot δ 15 N values, greater %Ndfa, and increased amount of N-fixed in plants treated to P and Rhizobium (Table 3 ).…”

Seeds with high molybdenum concentration improved growth and nitrogen acquisition of rhizobium-inoculated and nitrogen-fertilized common bean plants

“…This confirmed that N 2 fixation during early pod filling is extremely important for common bean (Kumarasinghe et al, 1992;Kimura et al, 2004). Estimates of contribution of N 2 fixation, assessed by 15 N isotope dilution in bean plants grown in pots with soil of other authors were rather similar: 50 to 72 % (Rondon et al, 2007) or 54 to 79 % (Chagas et al, 2010). Using the 15 N natural abundance method, Mortimer et al (2008) estimated contributions of biological fixation of 50 to 55 % in beans grown in nutrient solution.…”

“…A t-test at 0.05 probability was used to check the similarity of 15 N enrichment among plant parts for each harvest. In the different bean plant parts, 15 N enrichment was similar (Table 1), as verified by Wolyn et al (1991) in the best N 2 -fixing bean lines and by Chagas et al (2010) in a pot experiment. The leaves contained 67 and 40 % of the total N accumulated by inoculated plants 52 and 71 DAE, respectively, averaged across all treatments.…”

“…Brodrick et al (1992) observed that plants raised from seeds with a high Mo content produced lower nodule mass when the growth media was not supplemented with Mo. Kubota et al (2008) verified reduced nodule number at pod filling of bean plants raised from Mo-enriched seeds, and Chagas et al (2010) noticed that seeds with high Mo concentration reduced nodule mass of beans at high soil P availability. Additionally, Vieira et al (1998b) reported that the foliar Mo application 25 DAE reduced nodule number of field-grown beans, although without affecting nodule mass.…”

Control of Acid Phosphatases Expression from Aspergillus niger by Soil Characteristics

“…It can be inferred that in the soil, which is a complex system, the activity of phosphatases can also be controlled by other factors such as the concentration of substrates of the enzymes, the presence or absence of metals and others. Many elements are important for plant growth (Kevresan et al 2001) and biological nitrogen fixation (Chagas et al 2010) but amounts in excess can inhibit phosphatase acid activity (Huang and Shindo 2000;Tsekova et al 2002, Quiquampoix andMousain 2005). For example, acid phosphatase from Ustilago sp.…”