Effect of cowpea date and row arrangement on crop growth and yield in maize (zea mays L.) and cowpea (vigna unguiculata L. (walp) intercrop
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In order to improve the productivity of land in smallholder agriculture, intercropping of maize (zea mays L.) and cowpea (vigna unguicula L. (walp) has great potential. An experiment was conducted at the University of Zambia School of Agriculture Sciences Field Station in Lusaka, Zambia during the 200/2001 season to evaluate the effect of cowpea planting date and row arrangement on the growth and yield of maize and cowpea intercrop system. Cowpea (lutembwe) was planted on three planting dates as an intercrop with maize (pool 16), on the same day, 14 and 28 days after maize. Four row arrangements 1:1=two rows of cowpea 50cm apart in between inter-row space of maize 75cm apart and 1:2=two rows of cowpea 50cm apart in between inter-row space of maize 75cm apart. sole maize and sole cowpea were used as control treatments. The treatments were arranged in a split-plot design with three replications. Planting dates were the main-plots, while row arrangements were sub plots. Maize yield and yield components were not affected by the treatments. the average yield was 2735kg/ha. Cowpea yield and yield components were affected by treatments. The average yield was 1222kg/ha. Sole crop cowpea produced the highest grain yield (91934kg/ha) followed by the 1:1 row arrangement (1019kg/ha) and least was the 1:2 row arrangement (713kg/ha). The average number of pods/plants was 6. Sole crop cowpea produced the highest number of pods/plant (9), followed by the 1:1 row arrangement (5) and least was 1:2 row arrangement (3). The number of pods/plant were highest when the crop was planted 14 days after maize. this produced 8 compared to 5 when planted with maize or 4 when planted 28 days after maize. This produced 8 compared to 5 when planted with maize or 4 when planted 28 days after maize. There was a strong interaction of planting cowpea in 1:1 row arrangement (p<0.001) on number of pods/plant suggesting that planting cowpea in 1:1 row arrangement 14 days after maize is the most optimum. The average harvest index was 0.37. Sole crop cowpea produced the highest harvest index (0.43), followed by the 1:1 row arrangement (0.38) and least was 1:2 (0.29). Harvest index and number of pods/plant in cowpea were positively correlated with grain yield (r=0.95 and r=0.84, respectively) the land equivalent ration (1.51) and financial gross returns (ZMK 278,000/ha) data showed relative yield advantage (51%) and profitability (37%) of maize/cowpea inter cropping in the 1:1 row arragement. dry matter production, leaf area index of cowpea were affected by planting date 42 days after planting maize. Cowpea dry matter production, leaf are and leaf area index was significantly affected (p<0/001) by row arrangement and generally reached their maximum at 63 days after planting maize, and declined thereafter. The tallest plants were observed when cowpea was planted 28 days after maize, and in the 1:2 row arrangements. the results indicate that cowpea in the inter crop, with canopy always below that of maize, suffered from competition for photosynthetically active radiation, nutrients and water resources during vegetative and reproductive stages (nodulation, grain filling). The loss of leaves (leaf senescence, shedding) due to aging in cowpea explains the observed decline in dry matter production, leaf area index. The results suggest that the 1:1 row arrangement is a better alternative for growing maize together with cowpea in an inter crop system.
- Agricultural Sciences