Crop Interactions in Broccoli Intercropping

Abstract

ABSTRACT The research goals were to evaluate crop suitability to intercropping systems, to evaluate a population density limit to successful intercropping and to study the main factors responsible for crop performance when intercropped. Three experiments were carried out during 1995 and 1996 by intercropping broccoli either with contrast crops (pea, beans, potato or oats) or with similar crops (cauliflower or cabbage) in additive and substitutive designs at different intercropping rates. The overall intercrop characteristics as leaf area index, soil coverage and biomass yield were not related to a higher yield, and similar results were due to different factors. Land Equivalent Ratios (LER) similar to 1.0 were due either to a high and constant Relative Yield (RY) of the main crop associated with low RY of the secondary crop, or to trade-off between the RY of both associated crops. Similarly, a LER of 1.34 resulted from a reasonable performance of the dominated crop (beans) in the second experiment at the 50% additive design, whereas in the third experiment there was no dominating crop in the broccoli-potato intercropping but the LER reached 1.27. The mechanisms involved in the overyielding were the bean canopy plasticity and its temporal deployment asynchrony when compared with broccoli, allowing reduction of the competition for light, and the crop development temporal asynchrony between broccoli and potato, reducing the competition for production factors.