Response of common bean (Phaseolus vulgaris L.) to different levels of shade

Abstract

As a dominant component crop in intercropping systems, common bean was exposed to radiation deficit during whole plant growth period. Two determinate cultivars (Akhtar and COS16) were examined under four shading levels (0, 20, 40 and 55% reduction of full sun light) in a randomized block split plot design with three replications in 2004 and 2005. Shade levels and cultivars were allocated to main and sub plots, respectively. Increasing shade levels increased Leaf Area Index (LAI), Specific Leaf Area (SLA), Leaf Area Ratio (LAR), days to flowering, days to physiological maturity, grain filling period, mean grain weight and shoot dry weight. But the effects of shading on Leaf Weight Ratio (LWR) and grain yield per unit area were not significant. In comparison, grains per pod, grains per plant and HI decreased, as percentage of shade increased. It was, therefore, concluded that common bean could compensate the reduction in radiation and thus photosynthesis by increasing leaf area and then could prevent seed yield loss under shade stress via increasing grain filling duration and grain weight. © 2006 Asian Network for Scientific Information.