Influence of Cowpea Planting Date and Phosphorus Level on Striga Infestation and Performance of Pearl Millet in Mixture with Cowpea in a Nigerian Sudan Savanna

摘要

Pearl millet is traditionally grown in mixture with cowpea in the savanna region of Nigeria. Field experiments were conducted to determine the response of pearl millet to varying dates of planting cowpea and phosphorus levels during the 2005 and 2006rainy seasons. A randomized complete block design in factorial arrangement was used to evaluate five cowpea planting dates (0, 10, 20, 30 and 40 days after planting millet) and three phosphorus levels (0, 30 and 60 kg P205/ha), each replicated three times. The results showed that Striga counts and pearl millet plant height significantly increased with delay in planting cowpea, while number of grains/panicle, seed weight and grain yield/ha significantly decreased with delay in planting date. Increase inP levels significantly reduced Striga counts, but had no significant effect on grain yield/ha. Grain yield/ha was inversely associated with Striga counts (r = -0.28 to -0.42), but positively correlated with number of grains/panicle (r = 0.52 to 0.89) andseed weight (r = 0.27 to 0.35). The competitive effects of cowpea on pearl millet were balanced by substantial gain in cowpea grain yield for simultaneous or planting cowpea within 10 days after pearl millet. Therefore, both pearl millet and cowpea should be planted simultaneously or within 10 days after planting pearl millet as each proved beneficial to pearl millet and enhanced the productivity of the system in the Nigerian Sudan savanna.