Effects of relative planting dates in bean ( Phaseolus vulgaris L.) and maize ( Zea mays L.) intercropping patterns

Abstract

Planting date is one variable in tropical intercropping systems which is under direct control of the farmer. To study the impact of this factor on competition and yield, four bean cultivars were intercropped with maize using different relative planting dates for the two component crops in the pattern. These intercropping patterns were compared with monocultures of each crop in two successive seasons in the Cauca Valley of Colombia. Yields of beans, the lower story crop, were strongly affected by maize competition. The first crop planted in each pattern was less affected compared to monoculture than the crop which was planted later. Maize and bean yields were negatively correlated across cropping patterns and dates of planting. Competition from maize also reduced bean components of yield in all four bean cultivars. Yield reduction of climbing beans (compared to monoculture) due to intercropping was greater than yield reduction in the other three bean cultivars. Bean seed yield per plant, pods per plant and pods per m 2 were significantly correlated with maize yield. Maize yield was reduced by early competition from an advanced planting of each of the four bean cultivars. Nineteen of the 20 intercrop combinations (four bean cultivars × five dates) had LER (Land Equivalent Ratio) values greater than unity in both seasons. Highest LER values above 1.5 indicate a biological potential for intercropping to produce 50% more under these conditions than monoculture.