Time-course of dinitrogen fixation of promiscuous soybean cultivars measured by the isotope dilution method |
| |
| Authors: | R C Abaidoo K E Dashiell N Sanginga H H Keyser P W Singleton |
| |
| Institution: | (1) Department of Biological Sciences, UST, Kumasi, Ghana, GH;(2) International Institute of Tropical Agriculture, Ibadan, Nigeria, NG;(3) NifTAL Project, University of Hawaii, 1000 Holomua Avenue, Paia, HI 96779, USA, US;(4) c/o L.W. Lambourn and Company, Carolyn House, 26 Dingwall Road, Croydon CR9 3EE, UK e-mail: N.Sanginga@cgiar.org, Fax: +44-181-6818583, GB |
| |
| Abstract: | Soybean cultivars capable of nodulating with indigenous Bradyrhizobium spp. have been developed by the International Institute of Tropical Agriculture (IITA) and national programs in Africa in
order to avoid artificial inoculation by resource-poor farmers in Africa. The current selection procedure for enhanced N2 fixation is based on an assessment of nodule formation which does not directly quantify the proportions of crop N derived
from the atmosphere. We have monitored N accumulation patterns and N2 fixation in nine promiscuous soybean cultivars with different maturity periods, using the 15N dilution technique. Nodule development generally peaked at the early podfill stage for all cultivars except Tgx 1519-1D
and Tgx 1447-2D in which it continued to increase. The proportion of crop N derived from fixation (%NDFA) ranged between 51%
and 67%, 77% and 84%, and 66% and 73% at full bloom, early podfill, and physiological maturity stages, respectively. Total
N accumulation increased in all soybean genotypes with increasing plant age. Significant correlations (P<0.001) were established between nodule weight and %NDFA, even though this did not explain the relationship between nodule
development and N2 fixation in cultivars such as Tgx 1519-1D. Promiscuous soybean cultivars retained between 10% and 19% of total N accumulated
at the final harvest, in belowground biomass. Our results indicated that these soybean cultivars can derive substantial proportions
of plant N from N2 fixation in soils where compatible indigenous bradyrhizobia populations are adequate and effective. Also, we have substantiated
the claims that qualitative nodulation parameters currently used to select varieties with a high N2 fixation capacity need to be validated with other measurements of N2 fixation.
Received: 5 November 1998 |
| |
| Keywords: | Bradyrhizobium japonicum Bradyrhizobia spp Indigenous bradyrhizobia Nodule formation Moist savanna |
| 本文献已被 SpringerLink 等数据库收录！ |
|
