Grain yield and biomass response of a maize/dry bean intercrop to maize density and dry bean variety

Abstract

An experiment was conducted under dryland conditions at the University of Limpopo experimental farm at Syferkuil in Capricorn district in 2007/2008 and 2008/2009 growing seasons to determine the effect of maize density and dry bean variety on maize/bean intercrop performance. The trial was at 2×2×2 factorial consisting of eight treatments: two maize densities (24 700 and 37 000 plants/ha), two dry bean varieties (small white haricot and red speckled sugar bean) and two cropping systems (sole cropping and intercropping). Open pollinated maize variety ZM 523 (ex CIMMYT) was used in the trial. The results showed that maize density of 24 700 plants/ha yielded lower maize grain than the recommended 37 000 plants/ha and maize grain yields in sole cropping were significantly higher than in intercropping in both growing seasons. Intercropping of maize with red speckled sugar bean resulted in lower grain yield than intercropping of maize with small white haricot in both seasons. Increasing maize density to 37 000 plants/ha reduced number of branches per plant and grain yield of dry bean in both seasons. Sole cropping produced the highest dry bean grain yield component values. Intercropping maize and beans was advantageous at the different bean variety x maize density combinations with all, except one, achieving Land equivalent ratio (LER) values greater than 1. Intercropping of maize plant density of 37 000 plants/ha with red speckled sugar bean gave the highest total LER value in 2007/8 season but less than 1 in 2008/9 season. Intercropping was more advantageous than sole cropping in this study. The highest monetary values were achieved by the bean sole crops and their intercrops with 24 700 plants/ha maize. In this study maize densities of 37 000 plants/ha and 24 700 plants/ha were found to be suitable for sole maize and maize/bean intercropping, respectively. Key words: Maize/bean, intercropping, smallholder, maize density, bean variety.