Influence Of Plant Density And Intercropping On The Performance Of Elite Cowpea Varieties In Eastern Uganda

Abstract

Cowpea (Vigna unguiculata) is of major importance to the livelihoods of millions of relatively poor people in less developed countries of the tropics. In Uganda, cowpea occupies an economically important place among grain legumes especially in the eastern and northern regions where it is an important source of protein and household income. Two experiments were conducted at the National Semi-Arid Resources Research Institute (NaSARRI) Serere in Eastern Uganda during the first and second rains of 2011. Experiments were conducted to determine the influence of plant density and intercropping on the performance of elite cowpea varieties in eastern Uganda. Experiment 1 examined the effect of inter-row distance on the performance of elite cowpea varieties namely; IT85F-2841 (Spreading), MU-93 (Spreading), MU-93 (Semi erect), IT82D-889 (Erect) and two local cowpea varieties namely: Ichirikukwai (Spreading) and Ebelat (Erect). The treatments comprised of three inter-row distances; 45×30 cm, 60×30 cm and 75×30 cm. The treatments were arranged in a Randomized Complete Block Design (RCBD) with three replications. Experiment 2 investigated the effect of intercropping the elite cowpea varieties with maize in Eastern Uganda. This experiment was planted out in a split plot design of a Randomized Complete Block Design (RCBD) where maize row spacing was varied at two levels; 60×30 cm and 120×30 cm with three replicates. This gave rise to one inter-row and two inter-row treatments of cowpea between maize. Data were collected on cowpea growth parameters including; plant height, number of branches, number of leaves, days to 50 % flowering, and cowpea yield parameters including; number of pods per plant, seeds per pod, 100 seed weight (g), pod mass (g) and cowpea grain yield (t ha-1).

The results obtained indicated a significant (p = 0.05) difference in growth attributes observed among the cowpea cultivars. Plant population had no significant (p = 0.05) effect on most of the cowpea growth and yield parameters in this study. Elite cowpea varieties, MU-93 (spreading) and IT85F-2841 produced higher leaf yield than MU-93 (erect) and IT82D-889. Cowpea elite variety IT82D-889 flowered and reached physiological maturity earlier than all other cowpea cultivars. Cowpea row spacing of 60×30 cm at a plant population of 55,555 plants/ha gave consistently higher grain yield. Cowpea elite variety, IT82D-889 gave significantly (p = 0.05) the highest grain yield across the two seasons. Cowpea elite varieties IT85F-2841 and MU-93 (spreading), gave both higher cowpea leaf yields and high cowpea grain yields. Elite cowpea varieties, IT85F-2841 and MU-93 (spreading) with spreading growth habit were more significantly (p = 0.05) productive under intercropping than cowpea varieties IT82D-889 and MU-93 (erect) with erect growth habit. Land Equivalent Ratios showed that the best intercropping advantage occurred in 1 row maize : 2rows Cowpea intercropping. Maize planting pattern of 120×30 cm gave the highest maize grain yield than 60×30 cm planting pattern in the March to July 2011 rain season, yet the contrary happened in the September to December 2011 rain season. Cowpea elite variety, IT82D-889, should be recommended to Ugandan farmers for its early maturity and higher cowpea grain yield. However, further research should be conducted to test the yield performance of this variety on-farm and under different Agro ecological zones before it can be forwarded to the Uganda National Variety Release Committee. Cowpea varieties, IT85F-2841 and MU-93 (spreading), should be recommended as dual purpose cowpea cultivars to Ugandan farmers for their higher leaf yields and high grain yield. Farmers should also adopt the intercropping pattern preferably the 1 row maize : 2 rows Cowpea technique for yield advantage. However, more research is needed to further understand the associated additional benefits to enhance the benefits of intercropping achieved in this study.