Crop interactions in green bean intercropping with lettuce and radish

Abstract

The scope of improving vegetable production through suitable intercrop combinations has not yet been exploited to its full potential. Research goals were to evaluate crop suitability for intercropping systems, to evaluate the effect of fertilization and sowing dates on productivity of green bean, lettuce and radish and to study the main factors responsible for crop performance when intercropped under field conditions in 2009-2010. A field trial was set up in a random block system with four repetitions on experimental field of the Institute for Vegetable Crops in Smederevska Palanka, Serbia. Green bean (Phaseolus vulgaris L.) as a main crop was intercropped with leaf lettuce (Lactuca sativa L.) and radish (Raphanus sativus var. radicula L.). Also, all crops were grown in pure stands. The intercrops were created according to the method of replacement series. The treatments of fertilization consisted of following variants: control treatment without fertilization, microbiological and mineral fertilizers and farm yard manure. All the treatments were examined for two sowing periods, spring and summer. Yield variation was significantly affected by the year of sowing, fertilization and interaction of these factors. LER values were always larger than 1 in intercropping systems. The mechanisms involved in the overyielding were the green bean canopy plasticity and its temporal deployment asynchrony when compared with lettuce and radish, allowing reduction of competition for light and production factors. The study showed that green bean based intercrops might provide the higher total yields.