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International Journal of Agronomy
Volume 2014, Article ID 515629, 7 pages
Research Article

Potential of Cowpea Variety Mixtures to Increase Yield Stability in Subsistence Agriculture: Preliminary Results

1Institute of Agronomy in the Tropics, Georg-August-Universität, Grisebachstr. 6, 37077 Göttingen, Germany
2Global Program of Integrated Crop and Systems Research, International Potato Center (CIP), P.O. Box 22274, Kampala, Uganda
3Tropical Forages Program, International Center for Tropical Agriculture (CIAT), P.O. Box 823-00621, Nairobi, Kenya

Received 7 May 2013; Revised 3 October 2013; Accepted 7 November 2013; Published 23 January 2014

Academic Editor: Othmane Merah

Copyright © 2014 Joshua S. Okonya and Brigitte L. Maass. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Cowpea Vigna unguiculata (L.) Walp. is an important leafy vegetable and grain legume in Uganda. Unlike in commercial agriculture, where variety mixtures are known to give higher and more stable yields, the performance of cowpea variety mixtures in subsistence agriculture is little known. Mixtures containing up to four cowpea varieties were subjected to all possible 2-way, 3-way, and 4-way combinations. These cowpea varieties and mixtures were grown at three locations in Soroti and Kumi districts in order to assess the relative mixture effect, defined as: Mixture effect (%) = (mixture yield − pure line component average)/pure line component average × 100. Yield data was subjected to one-way ANOVA using the GLM procedure of SYSTAT. PLABSTAT was used to generate ecovalence ( ) values as a measure of stability with low ecovalence values indicating higher stability. The total cowpea dry matter (DM) yield was in the range of  3.7–6.7 g/m2 (leaf) and 12.1–36.7 g/m2 (grain), respectively. Mixture effects were between  −9.3–14.0% (leaf) and −30.3–21.9% (grain). Yield stability spanned   = 0.06–5.30 (leaf) and = 4.45–894.84 (grain). The results suggested that yields of cowpea variety mixtures grown in marginal environments were more stable than of single varieties but not all mixtures yielded more than single varieties.