Comparative study on photosynthetic characteristics of the Rhododendron delavayi cultivars.

Photosynthetic physiology index and diurnal change of photosynthesis,in 5 Rhododendron delavayi cultivars,such as jean de marle montague,Bule bell,which were introduced from Shijiazhuang,Hebei Province were studied.The photosynthetic light-response curve of different cultivars was also simulated.The results showed that net photosynthetic rate(Pn),transpiration rate(Tr),stomatal conductance(Gs),intracellular concentration of CO2(Ci),water use efficiency(WUE) of cultivars and the light saturation point in leaves of 5 cultivars were different and had obvious differences,and the light compensation point was similar.Diurnal change of net photosynthetic rate among cultivars were different,three cultivars showed twin-peaked curve with an obvious midday-depress,others showed single peak curves.Jean de marle montague and bule bell had high net photosynthetic rate(Pn),transpiration rate(Tr)and stomatal conductance(Gs),and showed high photosynthetic and potential productivity.The two cultivars also had low light compensation point and high light saturation point,showed high capacity for using light.Based on the photosynthetic characteristics,the two Rhododendron delavayi cultivars are suited to growing in Jiangsu Province