Light interception, agronomic performance,and nutritive quality of annual forage legumes as affected by shade

Abstract

Annual legumes can adapt to reduced light, a condition common in intercropping, by increasing the efficiency with which they convert energy into dry matter (DM). The performance of five forage legumes under reduced light–simulated by growing them under a shade net was evaluated in terms of agronomic adaptation, light interception, and the quality of forage. A third of the plot length was covered with Aluminet shade cloth 20–25 days after planting to reduce sunlight reaching the crop canopy to 30% of that without shade. Leaf area index (LAI) and light interception (LI) were significantly different depending on the species and shading up to 50–60 days after planting but not thereafter. Shading reduced DM significantly (p = 0.05), by 31–39% in 2009 and by 26–35% in 2010. Lima bean was affected the most (DM reduced by 43%), followed by pigeonpea (39%), whereas lablab (17%) and cowpea (29%) were affected the least. It affected dry matter in leaves and pods more than that in the stem. Shading had only a marginal influence on the concentration of crude protein,but increased the content of acid detergent fiber and neutral detergent fiber. Overall, lablab and cowpea were best adapted to reduced sunlight and therefore will be suitable for intercropping • Shade has a significant effect on canopy development and dry matter of all the legume species. • Shade has a significant effect on leaf chlorophyll, light interception, and leaf area index. • Impact of shade varies with legume species and affects relative feed quality, including digestibility.