Canopy Duration and Structure of Pigeonpea Intercropped with Upland Rice

Interactions between upland rice and three phenologically distinct pigeonpea cultivars were examined on a medium deep Vertisol. The productivity of each intercrop component and its respective sole crop was determined in terms of a crop performance ratio (CPR). The extra-early pigeonpea cultivar recorded the largest partial CPR of grain followed by early and medium genotypes. Spreading genotypes had a larger partial CPR than semi-compact genotypes. However, the CPR of intercropped rice was less (0.65–0.69) with spreading pigeonpeas but exceeded unity with compact types. The canopy structure of pigeonpea appeared to be more important than differences in phenology. A large range of light transmission coefficients (K) existed in pigeonpea (from 0.45 to 0.78) but it is argued that a further reduction in K may not be necessary since intercropped rice yield was unaffected even with a K of 0.64. The relative height of intercropped pigeonpea and upland rice may also determine competitive ability since rice is very sensitive to low light and shading, particularly during the reproductive phase