Abstract
In this study, 30 cowpea genotypes were assessed
for symbiotic N2 fixation in 2005, and 15 of them were reevaluated
in 2006 using the 15N natural abundance
technique. Shoot dry matter yield of cowpea genotypes
increased significantly in cvs. Vuli-1, Glenda, IT93K-2045-
29, IT90K-59, Omondaw, Apagbaala, and IT84S-2246
in 2005 producing about 3.0 to 3.6-fold more biomass
relative to cv. Vallenga. In 2006, seven out of the 15
cowpea genotypes tested (namely, IT97K-499-39,
TVu11424, Botswana White, IT84S-2246, Sanzie, Brown
Eye, and Glenda) also produced more dry matter than cv.
CH14. Shoot δ15N values ranged from −0.58‰ to 1.49‰
in 2005, and −1.51‰ to 1.40‰ in 2006, and these resulted
in %Ndfa values of 63.5–86.7% and 56.2–96.3%, respectively.
The amount of N-fixed was 49–178 kg N ha−1 in
2005 and 62–198 kg N ha−1 in 2006. Furthermore, there
was a direct relationship between the level of symbiotic N
nutrition and plant growth, and between grain yield and
amount of N-fixed in 2005 and 2006. As a result, genotypes
that fixed the most N also produced the largest biomass and
the greatest amount of grain yield. The observed relationship
between N2 fixation and biomass confirmed our view
that cowpea (and other grain legumes) can be concurrently
selected for higher N2 fixation, superior plant growth, and
greater grain yield. The high levels of N-fixed by many of
the cowpea genotypes in this study suggest that they can contribute large amounts of N to cropping systems in
African agriculture.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:tut/oai:encore.tut.ac.za:d1001434 |
| Date | 29 April 2009 |
| Creators | Belane, AK, Dakora, FD |
| Publisher | Springer |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Text |
| Format | |
| Rights | cSpringer 2009 |
| Relation | Biology and Fertility of Soils |
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