Response of African nightshades (solanum villosum) and spider plant (cleome gynandra) to farmyard manure and calcium ammonium nitrate fertilizer and pest infestation in Keiyo District, Kenya.
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The African Leafy Vegetables (ALVs) are particularly important as adjunct accompaniment to the staple cereal foods such as the East African corn meal (ugali). In the context of hidden hunger, these local vegetables do playa significant role in food security. Unfortunately exploiting the full potential of these crops has been hampered by lack of interest by policy makers, researchers, extension workers as well as farmers themselves, a situation that has contributed to food insecurity malnutrition among the resource poor farmers. In order to increase productivity and utilization of these ALVs, there is need to develop appropriate agronomic practices suited for farmers in specific agro-ecological zones. A study was carried out with an objective of determining the effects of various levels of farmyard manure (F.Y.M) and Calcium Ammonium nitrate (C.A.N) on vegetative growth, yield and quality (vitamins A & C, nitrates, iron, calcium, zinc, manganese and potassium) of Solanum villosum and Cleome gynandra in Keiyo district. Effects of prolonged cooking by the Keiyos on the quality attributes of these vegetables were also determined. The study was conducted between long rains and short rains of the Year 2002. Several insect pests were also identified and the damage they cause to these vegetables assessed. The experimental layout in the field was a RCBD with four replicates. The treatments were set at four levels of farmyard manure (5,10,15, 20 tons/ha) and four rates of Calcium Ammonium nitrate fertilizer (100, 200, 300, 400 kg/ha). Results revealed that the addition of various rates of Farmyard manure and Calcium Ammonium nitrate that were tested significantly improved vegetative growth and increased leaf and seed yields of both Solanum villosum and Cleome gynandra (p<0.05). Both leaf and seed yields obtained from plants grown with farmyard manure were generally higher than from those with C.AN fertilizer. The incorporation of either farmyard manure or C.AN fertilizer increased vitamin A content. The Farmyard manures increased vitamin C while the application of C.AN fertilizer decreased vitamin C. The application of 300kg/ha of C.AN fertilizer increased the accumulation of nitrates, while farmyard manure did not. The addition of various rates of F.Y.M and C.AN fertilizers did not significantly affect the concentration of zinc, manganese and potassium in both plants (p<0.05). The incorporation of either farmyard manure or C.AN fertilizer decreased iron content in both vegetables. In all experiments, the farmer's crop, in all attributes though better than the controls, was comparable to low fertilizer levels applied. Traditional methods of boiling the ALVs for long significantly reduced vitamin A & C, nitrates, iron, calcium, zinc, manganese and potassium. The two vegetables were found to be attacked by a total of twelve insect pests. These were Cutworms (Agrotis spp), black aphids (Aphis fabae), cotton aphids (Aphis gossypi), Leaf miner (Lyriomyza spp), Red Spider mites (Tetranchus spp) , Root-Knots nematodes (Meloidyne spp) , Flea beetles (Chrysomelidae spp), Epilanchna beetles (phytophagous Lady birds), Diamondback moth (Plutella xylostella) African bollworm (Helicoverpa armigera), Systates weevils (systates pollinosus) and Flea beetles (Chrysomelidae spp). Most pest species were recorded at 8th week after planting. In conclusion the kind and rate of fertilizer applied, the season of growth, plant age, farmer's agronomic practices as well as cooking influenced the quality attributes of Solanum villosum and Cleome gynandra, significantly (p<O.05). This investigation shows that Solanum villosum and Cleome gynandra is liable to attack by a large variety of insect pest species.