东祁连山杜鹃属植物光合作用特点的研究

Study on photosynthetic characteristics of Rhododendron shrubs in Rhododendron communities in eastern Qilian Mountains

对东祁连山杜鹃灌丛中杜鹃属植物光合作用特点的研究结果表明:4种杜鹃的净光合速率较低,头花杜鹃、百里香杜鹃、烈香杜鹃和陇蜀杜鹃在7月分别为5.06、6.13、7.23、7.44 m mol CO2 m-2穝-1,在10月分别为-0.12、0.032、-0.063、1.218 m mol CO2 m-2穝-1。前3种杜鹃的净光合速率与光通量密度存在正相关关系(r分别为0.936 4、0.850 1、0.817 8),陇蜀杜鹃则相关性不显著。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穝-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穝-1时开始下降。4种杜鹃在13 : 00～14 : 00发生光合午休现象。

The study on photosynthetic characteristics of Rhododendron shrubs in Rhododendron community in eastern Qilian Mountains indicated that the net photosynthetic rates of Rhododendron capitatum, R. thymifolium, R. anthopogonoides and R. przewalskii were 5.06, 6.13, 7.23, 7.44 m mol CO2穖-2穝-1 in July, and -0.12, 0.032, -0.063, 1.218 m mol CO2穖-2穝-1 in October. There were positive relationship between photosynthetic rates and light intensity in Rhododendron capitatum, R. thymifolium and R. anthopogonoides (r=0.936 4, 0.850 1 and 0.817 8 respectively). The net photosynthetic rates of Rhododendron capitatum and R. thymifolium declined when light intensity reached 1 000 m mol CO2穖-2穝-1 and it was 1 400 m mol CO2穖-2穝-1 for R. anthopogonoides and R. przewalskii. The midday decline occurred from 13 : 00 to 14 : 00 in all Rhododendron shrubs.