ISSN:
1432-0789
Keywords:
Key words Biological nitrogen fixation
;
Cowpea
;
N assimilation
;
15N isotope dilution
;
P assimilation
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Geosciences
,
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Abstract A greenhouse experiment was conducted to investigate the effect of a P application (0 vs. 50 mg P kg–1) on yield, nodulation, and N2 fixation by three cowpea cultivars (Soronko, Amantin, and IT81D-1137) using the 15N isotope-dilution method. When P was not applied the inoculated cowpea genotypes showed significant differences (Soronko〉Amantin〉 IT81D-1137) in N accumulation, in contrast to the uninoculated cowpea cultivars, which accumulated similar amounts of N. The differences in shoot N in inoculated plants were thus caused by differences in N2 fixation. The average values of N fixed (for both P levels) were 74% in Soronko, 59% in Amantin, and 42% in IT81D-1137,correspondingto80,51, and 24mgN plant–1, respectively. Inoculation increased the total shoot-N accumulation in cv. Soronko by 270% without P and by 204% with P, cv. Amantin by 152 and 104%, and cv. IT81D-1137 by 74 and 58%, respectively. With P, the % N derived from atmosphere (%Ndfa) was 42% for IT81D-1137, 62% for Amantin, and 76% for Soronko. The high value for Soronko indicates that in a soil of medium fertility, certain cowpea cultivars are capable of satisfying their total N requirement through N2 fixation. The P effect on N2 fixation was mainly in the total amount of N fixed rather than on the percentage derived from the atmosphere.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00384426
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