Agricultural Science Digest

Chromolaena odorata and Corchorus olitoriuswere grown at 5, 10, 15 and 20 plants/pot to evaluate the response of individual plants to intraspecific competition after 10 weeks. Both species showed considerable plasticity in plant height, root dry matter production and biomass partitioning but competitive effects were significant in respect of leaf production, leaf area and photosynthetic efficiency (as indicated by LAR). Competitive effects were also significant with resport to shoot and total dry weights and individual plant weight (weight per plant) in C. Olitorius. The reduction in leaf area was greater with increasing plant density in C. odorata while C. olitorius showed greater reductions in leaf production and LAR. Weight per plant was reduced significantly by 0.56 g for each, unit increase in plant density for both species. Differences in plant response to intraspecific competition were due to growth habit and physiology. These differences have practical implications on population regulation and relative competitive ability of these two weeds in cropping situations.