EFFECT OF RELATIVE SOWING TIME ON GROWTH AND YIELD OF VEGETABLE COWPEA (VIGNA UNGUICULATA (L.) WALP) AND MAIZE (ZEA MAYS L.) IN VEGETABLE COWPEA/MAIZE INTERCROPPING SYSTEM

Improved varieties of both vegetable cowpea (IT92KD-263-4-1) and maize (OBA 98) were grown in mixture at Michael Okpara University of Agriculture, Umudike research farm for two cropping seasons (2006 and 2007) in order to determine the suitable relative sowing time of the component crops. The experiment was laid out in a randomized complete block design and with three replicates. The treatments were vegetable cowpea and maize separately planted in their pure stands, vegetable cowpea and maize simultaneously sown on the same day, vegetable cowpea sown 2, 3, 4 weeks before maize and vegetable cowpea introduced 2, 3 and 4 weeks after maize was sown. Widest leaf area, heaviest total aboveground dry matter and nodules per plant of vegetable cowpea were attributed to the vegetable cowpea sown 4 weeks before maize. Similarly, maize leaf area index, aboveground dry matter, number of grains per cob, 100-seed weight and grain yield per hectare were highest when maize was sown 4 weeks before introducing vegetable cowpea. The highest LER of 1.61 and 1.58 in 2006 and 2007, respectively were attributed to the vegetable cowpea sown 4 weeks after maize. It was therefore, recommended that the resource poor rural farmers should introduce the vegetable cowpea 4 weeks after sowing the maize seeds since they usually target the combined yield from the component crops of the farmlandÂ