This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Danso, S. K. A. Articles by Awonaike, K. O. Search for Related Content PubMed PubMed Citation Articles by Danso, S. K. A. Articles by Awonaike, K. O. Agricola Articles by Danso, S. K. A. Articles by Awonaike, K. O.

 Previous Article  |  Next Article 

Appl Environ Microbiol. 1990 June; 56(6): 1793-1798
Copyright © 1990, American Society for Microbiology. All Rights Reserved.

Effect of Postemergence, Supplemental Inoculation on Nodulation and Symbiotic Performance of Soybean (Glycine max (L.) Merrill) at Three Levels of Soil Nitrogen

S. K. A. Danso^*, F. Zapata and K. O. Awonaike

¹ Joint FAO/IAEA Division, P.O. Box 100, A-1400 Vienna, and Soils Unit, IAEA Laboratories in Seibersdorf, A-2444 Seibersdorf,² Austria

ABSTRACT

The influence of a supplementary bradyrhizobial inoculation after an initial seed slurry inoculation with the same strain on nodulation and N₂ fixation in soybeans was examined in the greenhouse. The plants were grown in a Typic Eutrocrepts soil: sand mixture containing 25, 65, or 83 mg of N per kg (i.e., native soil N plus ¹⁵N-labeled ammonium sulfate). Harvests were made at early flowering and physiological maturity. The supplementary inoculations which were made 14 or 21 days after planting (DAP) caused formation of substantially more nodules than the single slurry inoculation did. Autoregulation was therefore not completely successful in preventing subsequent infections. For the slurry-inoculated plants, at both harvests the proportion of N derived from fixation was greatest in the soil containing the least N, and only slight increases in N₂ fixation resulted from a second inoculation. The inhibition of N₂ fixation at the higher N levels was significantly reduced by a second inoculation at 21 DAP; this treatment resulted in at least a doubling of both the percentage and total amount of N₂ fixed by the single slurry inoculation at physiological maturity. The N₂ fixation increases resulting from the supplementary inoculation at 14 DAP were less pronounced and not significant. Greater N₂ fixation was frequently not reflected by increased total N or dry matter yield, suggesting that the major benefit of the increased fixation was a decreased dependence of plants on soil N for growth.

^* Corresponding author.

Present address: Institute of Agricultural Research and Training, Obafemi Awolowo University, P.M.B. 5029, Ibadan, Nigeria.

This article has been cited by other articles:

• Zahran, H. H. (1999). Rhizobium-Legume Symbiosis and Nitrogen Fixation under Severe Conditions and in an Arid Climate. Microbiol. Mol. Biol. Rev. 63: 968-989 [Abstract] [Full Text]