Intercropping of beans (Phaseolus vulgaris L.) and sugar-cane: The effect of inter-specific competition on the growth of plant cane

Abstract

The competitive effects of intercropped beans (maturation period: three months) on the growth, tiller development and yield of plant sugar-cane (maturation period: 18 months) in the subhumid coast-hinterland of Natal were investigated over two seasons. In the first season rainfall was exceptionally low and intercropping reduced tiller emergence, leaf area and dry matter production in the sugar-cane. Lower soil and leaf water potentials were measured in the intercropped treatments. Beans appeared to be the stronger competitor and produced yields of up to 940 kg ha⁻¹. Second season rainfall was favourable and tiller emergence was more prolific in the intercropping treatments. This combined with a higher degree of tiller mortality in the monoculture in the preceding autumn and winter, compensated for reduced dry matter production in the intercropped treatments in the first summer. As a result there was no difference between treatments in the final yield of cane and sucrose. Availability of soil moisture was the major factor affecting plant response to intercropping.