Preliminary study on effect of shading on the growth and yield of Medicago sativa

An experiment was carried out using three Medicago sativa varieties by controlling light intensity with shading net to study the growth in different shading treatments (the control, shaded 50% and shaded 80％), and to analyze indices of growth and yield. The results showed that the content of chlorophyll a and b was not affected significantly by shading treatments, but chlorophyll a/b decreased with the increased shading intensity. The plant height, stem/leaves ratio, yield of alfalfa decreased with the increased shading intensity. The yields of whole year in the control were three times and eight times in shaded 50% and 80% respectively. The percent of first cutting yield in total yield increased with the higher shading intensity. The shading intensity should be not more than 50% if planting M.sativa in shading environment, at the same time the yield was priority to first cutting yield and should reduce cutting times.