Authors : Lanyasunya , T.P. Wang , H. Rong , A.L. Chek , E.A. Mukisira and S.A. Abdulrazak
Abstract: This study was conducted in Naivasha, Kenya over a period of 15 weeks to determine the effect of maturity on mineral content in Commelina benghalensis (Giant var M). Immediately after field preparation, representative soil samples were taken for mineral profiling. Thereafter, 60 plots of 2x2 sq. m size were demarcated and allotted to 5 similar blocks of 12 plots each in a randomized complete block design. Each plot received a total of 50 vines (15 cm long with 3 nodes each) evenly planted in 5 rows (2 m length and 30 cm apart). All the plots were planted on the same day and kept weed free throughout the study. The forage was harvested at 6, 8, 10, 12 and 14 weeks after planting (excluding the 1st 7 days considered as rooting period) in sequential manner beginning with block 1 to 5, each time leaving a stubble height of 5 cm. From each plot, representative herbage grabs were made, chopped into 2 cm pieces and mixed thoroughly. Two composite samples of about 1 kg each were then taken for dry matter determination and mineral analysis through the standard procedures. Results showed wide variations in the plant tissue concentration change patterns of different mineral elements over the study period. From the results, it was noted that P and Mg levels recorded a marginal decline of 0.6 and 13.8% respectively between 6 and 14 weeks. This represented decline rates of 8.93 and 7.14 mg kg -1 DM d -1. On the contrary, K registered a 31.39% increase from 6.18 at 6 to 8.12% at 14 weeks. Sodium and Ca recorded 35.19 and 49.78% drop in concentration over the same period. The level of Cu was fairly consistent throughout the study. That of Mn was observed to be inconsistent. Zinc levels however showed rapid decline 66.68% over the study period. From the results presented it was concluded that, macro-mineral content in Commelina benghalensis significantly decreased with advancing age of the forage. Trace elements, though were not significantly affected by age, their concentration occurred in quantities below ruminant livestock requirements suggesting the need for trace mineral supplementation. It was further concluded that, owing to high macro-mineral content, the giant Commelina benghalensis has a potential for enhancing the levels of essential minerals in the diets of ruminant livestock on smallholder farms in Kenya.
Lanyasunya , T.P. Wang , H. Rong , A.L. Chek , E.A. Mukisira and S.A. Abdulrazak , 2006. Effect of Maturity on the Mineral Content of the Giant Commelina benghalensis . Research Journal of Biological Sciences, 1: 74-78.