Nitrate levels and stages of growth in hypernodulating mutants of Lupinus albus. I. N2 fixation potential

Abstract

This work aimed to evaluate physiological parameters, nodulation response and N 2 fixation rate in mutants of Lupinus albus in comparison with the standard Multolupa cultivar. Two nitrate levels (0 and 5mM) and two evaluation periods (7 and 10 weeks) were used. Significant differences were observed among genotypes, in relation to fresh nodule weight, nitrate levels and growth stages. The overall average for nitrate level differed between them where 5mM severely inhibited the number of nodules, reaching a 49.5% reduction in relation to treatment without nitrate. There were no behaviour differences among genotypes, nor among evaluation periods. Although the level of nitrate did not influence the production of shoot dry matter in relation to the average among levels applied, the L-135 genotype, being an inefficient mutant, reached very low values. There were no significant differences in electron allocation coefficient (EAC) among nitrate levels, nor among genotypes studied. However, the evaluation periods revealed differences, where the EAC for the seventh week had a higher value than that for the tenth week, when a 5mM aplication was evaluated. The N 2 fixation rate (N 2 FIX) showed the existence of the nitrate interference in fixation, given that the application of 5mM severely reduced. However, there were no differences among the genotypes and it was noted that the fixation rate was much higher in those that received nitrate. The L-88 and L-62 genotypes were the ones that have shown best adaptability in this experiment, thus being able to be recommended for new studies with higher nitrate levels and different evaluation periods. The nitrate (5mM) interferes in the nitrogen fixation rate, given that all the genotypes were affected by the level applied.

Nodulation and Growth of a Supernodulating Soybean Mutant SS2-2 Symbiotically Associated with Bradyrhizobium japonicum

“…Results of this study were consistent with the conclusion of Hansen et al (1992) that the supernodulators were producing relatively more nodular tissue than normally-nodulating types (non-mutated plant) in the absence of soil nitrogen. Nodulation behaviour in SS2-2 was similar with that of a pea mutant (Pisum sativum) (Jacobsen and Feenstra 1984) and a lupine hypernodulating mutant (Lupinus albus) L-62 (Burity et al 1999). It was shown that without nitrogen supply, the mutant presented better nodulation in association with Rhizobium.…”

“…The yield of supernodulating mutant SS2-2, generated from Sinpaldalkong 2 that was mutagenized by EMS (Lee et al 1997), was not changed significantly due to nitrogen supply. Furthermore, non-inoculated plants of mutants, SS2-2 and nts382 showed greater nodules number and nodule mass, as well as greater ARA than their wild types, regardless of the level of exogenous nitrogen supply (Ha et al 1999). Investigation of nitrogen fixation and agronomical traits of SS2-2 in association with Rhizobium has not been reported.…”

Isolation and Evaluation of Salt-Tolerant Microorganisms and Their Impact in Adaptation of Faba Bean to Salinity Stress

“…Dry weight of nodules decreased due to the treatment 100%N than the treatment of 25% N and other treatments. The reason may be due to the presence of nitrogen element in soil with high amounts which affect nodule formation (Burity et al, 1999 &Tham andTham, 2007). Likewise, mycorrhizal inoculation had stimulated effect on nodules dry weight, this finding agreed with those of Li-ShuMin, et al (2004) who indicated that dual inoculation of faba bean plants with AM fungi and Rhizobium leguminosorum significantly increased the number and weight of nodules.…”