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Assessment of N2 fixation in 32 cowpea (Vignacunguiculata L. Walp) genotypes grown in the field at Taung in South Africa, using 15N natural abundance

Abstract
The aim of this study was to evaluate plant growth, grain yield and symbiotic N contribution by 32
cowpea genotypes, at Taung in South Africa. The data from a 2-year field study conducted in 2005 and
2006 showed that genotypes Fahari, Pan 311 and Glenda exhibited the highest dry matter yield and N
contribution as they produced 2.9-, 2.7- and 3.5-fold more dry matter than cv. ITH98-46 and yielded 2.7-,
2.2- and 3.2-fold more N than cultivar ITH98-46 from IITA. Except for Benpila, all the 32 cowpea
genotypes derived between 52.0 and 80.9% of their N nutrition from symbiotic fixation in 2005, with
IT82D-889, Botswana White, IT93K-2045-29 and Ngonji exhibiting the highest %Ndfa values. The
genotype Fahari showed the highest amount N-fixed (182 kg N-fixed/ha), followed by Pan 311, Glenda,
TVu11424 and Mamlaka which contributed 160, 146, 130 and 125 kg N/ha, respectively. Genotypes Pan
311, Fahari and Glenda were among those that produced highest grain yield in 2005 and except for
CH14 and IT86S-2246 (which produced 131 kg N/ha each), Fahari, Glenda and Pan 311, were again the
highest in symbiotic N contribution (112, 106 and 105 kg N/ha, respectively). Grain yield was similarly
high in Glenda, Pan 311 and Fahari (3.3, 3.1 and 2.9 t/ha, respectively) in 2006. In general, these data
show that genotypes that fixed more N also produced more biomass and grain yield and are therefore,
the best candidates for inclusion in cropping systems as biofertilizers.

Identiferoai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:tut/oai:encore.tut.ac.za:d1001477
Date21 September 2011
CreatorsBelana, AK, Dakora, FD, Asiwe, J
PublisherSymbiosis
Source SetsSouth African National ETD Portal
Detected LanguageEnglish
TypeText
FormatPdf
Rights© 2011 Academic Journals
RelationAfrican Journal of Biotechnology

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