Studies on competition between associated bean and maize crops

The degree of interaction and subsequent yield reduction between associated crops depends in part on the temporal overlap in their growth cycles. Physical differences between associated crops such as height and leaf display, rooting vol and relative population densities also determine whether the interaction will be equal or not, with one crop clearly dominant. In the studies reported here, crop-to-crop interaction was maximized by simultaneous, high-density plantings of both crops. The height difference between the bean and maize and the variation in the height parameter among growth habits produced crop-to-crop interactions ranging from near-equal to plainly dominant- suppressed. This latitude in degree of crop interaction was focused toward the following objectives: (1) Breeding. To compare growth and developmental responses of the different bean growth habits in monoculture and associated with maize, to relate plant growth responses to resultant grain yield in both systems, and to evaluate the possibility of a genotype x cultural system interaction in the yield response. (2) Physiology. To test 3 hypotheses (spatial and temporal competition for resources, and microclimate modification) accounting for the effect of associated maize on beans and to examine a postulated bean effect on maize growth and yield. (AS)