The net photosynthetic rates of Rhododendron capitatum and R. thymifolium declined when light intensity reached 1 000 m mol CO2?-2?-1 and it was 1 400 m mol CO2?-2?-1 for R. anthopogonoides and R.

• 头花杜鹃和百里香杜鹃的净光合速率在光通量密度达到1 000 m mol m-2?-1时开始下降,而烈香杜鹃和陇蜀杜鹃则在达到1 400 m mol m-2?-1时开始下降。