Effect of source-sink ratio changing on yield formation of Cynanchum bungei Effect of planting density on canopy sink-source feature and yield of different dwarf varieties of summer squashes (Cucurbita pepo L.) Effects of leaf removal on growth and physiological characteristics of Rehmannia glutinosa Effects of Source/Sink Ratio on Boll Weight and Physiological Activities of Leaves at Middle and Lower Fruiting Branches in Cotton