Growth, Yield and Nutritional Quality of Five Bambara Groundnut (Vigna Subterranea (L) Verdc.) Landraces to Different Plant Population Densities

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JUNE, 2010
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A field experiment to study the effect of plant population density on the growth, yield and nutrient quality of five bambara groundnut landraces was conducted at Kwame Nkrumah University of Science and Technology, Kumasi; at the Department of Crop and Soil Sciences in 2008 cropping season. The experimental design was a split plot with bambara groundnut landraces; Nav 4, Nav Red, Black eye, Mottled cream and Burkina as the main plot factor and the population densities (5,6.7 and 10 plants m-2) as the subplot factor. Two seeds per hill were planted on the 17th of May and thinned to one seed per hill 21 days after sowing. Weeding was done when necessary. Growth analysis were carried out at six different sampling periods during which number of leaves, leaf area, petiole length, canopy spread, total dry matter, petiole internode ratio and leaf area index were measured. Yield and components of yield- number of pods per plant, number of seeds per pod, mean seed weight as well as harvest index were also measured during harvest. At final harvest, proximate analysis was carried out on air dried seed samples of the five landraces. Results indicated that increasing plant population density resulted in higher pod yield. The highest density of 10 plants m-2 produced significantly (P < 0.05) the greatest pod and grain yield of 3399 kg/ha and 1684.7 kg/ha respectively. Similarly, density of 10 plants m-2 produced significantly higher number of pods than the lowest population density treatment. However, the number of seeds per pod and mean seed weight were not affected by plant population. Although, most vegetative data were not significantly affected by varying plant population, crop growth rate, net assimilation rate and leaf area index were also significantly higher in the low population density treatment than other treatments. Yield data among the landraces were statistically similar, except with the number of pods per plant, where the Mottled Cream landrace produced significantly lower pods than the other landraces. However, the mean seed weight, pod and seed harvest indices of this landrace were superior to those of other landraces. Therefore Mottled Cream is recommended for sole cropping, Nav 4, Nav Red, Black Eye in intercropping situations and Burkina for subsistence farming. The spacing of 50 cm x 20 is recommended for cultivation bambara groundnut. Seed analysis showed that the landraces contain 26.88-33.75% protein; 54.89-63.67% carbohydrate; 2.45-4.29% fat; 1.59-3.13% fibre and 2.45-4.28% ash. The mineral composition (mg/100g) was Fe = 1.71-4.56, Ca = 88-144, K = 1700-2200 and Na = 4.20-5.00. The results indicated that the landraces contained protein, carbohydrate, fat and fibre in levels that provide balanced nutrition. Cultivation and use of these landraces therefore should be encouraged because the legume has great potential to contribute to food security in Ghana.
Thesis Submitted to the School of Postgraduate Studies of Kwame Nkrumah University of Science and Technology, Kumasi in Partial Fulfillment of the Requirement for the Award of Master of Science (Agronomy).