PRODUCTIVITY AND LIGHT INTERCEPTION UPLAND RICE-LEGUME INTERCROPPING SYSTEMS

The interaction between upland rice and grain legumes (cowpea, groundn ut, pigeon pea) in intercropping was investigated on a Vertisol over t wo years. Generally, intercropping was advantageous with a small reduc tion in rice yield and a substantial increase in yield of the legume. Pigeon pea-rice systems gave the highest intercropping advantage of 41 -74% in the first year. In the second year, high intercropping advanta ges were recorded for cowpea and pigeon pea intercrops but the indeter minate pigeon pea cv. Hy3C reduced the expected rice yield by half. Hi gh irradiance early in the rainy season increased the growth and yield of both rice and legumes compared to the previous season, but intercr op rice was less competitive than Hy3C. Canopy cover of rice was slowe st compared to cowpea and pigeon pea, largely because of the erect lea f arrangement of rice. Intercropping invariably increased the amount o f radiation intercepted due to faster canopy cover, i.e., spatial comp lementarity. It was concluded that determinate legumes are more approp riate for intercropping with upland rice.