Interaction between maize and soybean sown simultaneously and at intervals in a humid tropical environment

Maize (Zea mays L.) and Soybean (Glycine max M.) were sown simultaneously and either of the component crops relay-sown at intervals of 14, 21 and 28 days in mixtures at Ekpoma in the rain-forest zone of Nigeria in 1997 and 1998. Their monocultures were sown at the same density as the mixtures. Interactions between the two crops sown at the different intervals were significant. Relay-sown maize 21 or 28 days after sowing soybean significantly delayed tasselling for 35 days, reduced ear weight, ear height, and also maize grain yield. Relay-sowing of soybeans, 14 or 28 days after sowing maize, significantly delayed flowering, reduced number of pods and soybean grain yield. The land equivalent ratios (LER) and total grain yields were significantly lower when maize was relay-sown 28 days after sowing soybean and when soybeans were introduced between 21 and 28 days after sowing maize. Maize and soybean can be sown simultaneously or soybean introduced after maize in the humid tropical environment provided the component crops are not introduced later than 14 days after planting the other component crop.