Response of cowpea (vigna unguiculata) under varying rates of phosphorus in tropical soils.
Bbosa, Wilfred Kisaakye
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COWPEA (Vigna unguiculata.) is an important source of protein, minerals and food for the majority of the poor population in Sub-Saharan Africa. However, its contribution to grain yield and micronutrient level is constrained by moisture stress and low available soil phosphorus and nitrogen, to mention but a few. An experiment was conducted at Makerere University Agricultural Research Institute-Kabanyolo (MUARIK) which is located at an altitude of 1217 meters above sea level on coordinates 0.16˚24'16 N and 32.5˚27'34E, approximately 19 km in the northeast of Kampala at Kabanyolo in Lake Victoria Crescent. The main objective of the experiment was to evaluate the response of cowpea under varying rates of phosphorus in tropical soils. The cowpea variety used in the experiment was Asomdwee (IT94k-410-2) variety. The treatments included TSP fertilizer applied at: 0 kg/ha, 10 kg/ha, 20 kg/ha and 30 kg/ha and these were arranged in a completely randomized block design with five replicates. Data was collected on number of leaves, leaf area, plant height, number of nodules and number of effective nodules and biomass at harvesting. The response of the growth parameters (plant height and leaf area) significantly differed with increase in fertilizer rate. In terms of plant height, the highest plant height response was 82.5 cm obtained from 0 kg/ha TSP which was the control experiment. For biomass yield in terms of number of pods per plant and number of seeds per pod, treatment of 30 kg P/ha provided the highest yield (24.2 and 15.7 respectively). It can be concluded that application of 30 kg /ha can enhance yield of cowpea. Therefore, the 30 kg P /ha should be adopted by farmers since it led to the highest yield.