the effect of different crop plant densities on radiation absorption and use efficiency by corn (zea mays l.) and bean (phaseolus vulgaris l.) intercropped canopy

in order to determinate the effects of plant densities in intercropped corn (zea mays l.) and bean (phaseolus vulgaris l.) on radiation absorption and use efficiency, an experiment was conducted at the agricultural research station, ferdowsi university of mashhad, iran during growing season of 2007-2008. this experiment was conducted in low input system. a randomized complete block design with three replications was used. treatments were included bean intercropping with corn in normal density of bean plus 10%, 20% and 30% excess bean c (b+10%), c (b+20%), c (b+30%), increasing in density bean intercropping with corn in normal density of corn plus 10%, 20% and 30% excess corn b (c+10%), b (c+20%), b (c+30%) and sole crops of corn (c) and bean (b). results indicated that leaf area index, radiation absorption, total dry matter and radiation use efficiency of corn increased in all intercropped treatments compared to sole cropping, but it reversed for bean. it seems that complementary and facilitative effects of intercropping were more for corn. range of corn and bean radiation use efficiency was from 1.92 g.mj-1 (in sole cropping) and 0.72 g.mj-1 {in (c+30%) (b+30%)} to 2.30 g.mj-1 {in c (b+30%)} and 1.45 g.mj-1 (in sole cropping), respectively.