高地省藤幼苗光合作用日变化特征

Diurnal Variations in Photosynthesis of Calamus nambariensis var. alpinus at Seedling Stage

利用Li-6400便携式光合测定仪研究了高地省藤苗期光合作用日变化特征,结果表明:①高地省藤5个月幼苗Pn、Tr日变化曲线均呈双峰型,12:00左右出现明显的光合"午休"现象,峰值出现在10:00和14:00左右,"午休"过后,气孔扩张,且蒸腾增加量高于Pn增加量;②水分利用效率WUE和气孔限制值Ls也呈双峰趋势,在10:00均达最大值,WUE光合"午休"时降至最低,16:00出现次高峰,Ls变化较WUE平缓,光合"午休"时略有下降,18:00时降到最低值;③相关性分析结果表明:对Pn影响最大的因子是Ls,其次是Gs、WUE、Tr、RH、PAR、VPD、Ca、Ta,这些因子与Pn均呈正相关,但均未达到显著水平,高地省藤光合速率变化是多因素综合作用的结果。

Diurnal variation in photosynthesis of Calamus nambariensis var. alpinus at seedling stage was studied by Licor-6400 portable photosynthetic system. The results demonstrated that 5-month C. nambariensis var. alpinus seedling had an obvious double peaks curve of diurnal variation both in net photosynthesis rate（Pn） and transpiration rate（Tr） with obvious midday depression at 12 and the peak value appeared at 10 to 14. For the reason of the stretch of stoma, the increment of Tr was higher than that of Pn after the midday depression. The diurnal variation trend of water use efficiency（WUE） and stomatal limitation value（Ls） were also double peaked with the peake at 10. WUE reached the second peak at 16. The changing trend of Ls was lower than that of WUE and got the lowest value at 18. Correlation analysis resulted that Pn had relationships with many environmental factors but not a significant level. The influencing factors to Pn were ordered as follows： LsGsWUETrRHPARVPDCaTa.