格木光合日变化及生理生态因子对光合作用的影响

对格木（Erythrophleum fordii）1年生营养杯苗的叶片光合作用和环境因子动态变化进行了测定,探索格木苗木光合日变化规律,分析光合作用与生理生态因子间的相互关系及影响光合作用的主要决策因子。结果表明：净光合速率（Pn）日变化呈现＂双峰＂曲线,有明显的光合＂午休＂现象;叶片温度（Tl）、蒸腾速率（Tr）、水汽饱和压亏缺（Vpdl）的日变化与光合有效辐射（PAR）一致,峰值在中午;空气相对湿度（RH）的谷值在中午;气孔导度（Gs）的日变化随时间的变化而变化,全天出现＂三峰＂值,最高峰值在16：00;胞间CO2浓度（Ci）的日变化呈＂双峰＂曲线;水分利用效率（WUE）、光能利用率（LUE）的日变化呈明显＂U＂型。影响格木苗木Pn的生理生态因子主要有PAR、Ca（大气CO2浓度）、Ta（空气温度）、RH、Gs、Tr、Tl和Vpdl,其中PAR、Ca、Tl和Vpdl为影响Pn日变化程度最高的因子,PAR为主要决策因素,Tl为主要限制性因素。由此可见,格木的光合日变化有一定的规律,同时生理生态因子对光合作用的影响及影响程度也各不相同。

Diurnal Photosynthetic Change of Erythrophleum fordii Oliv and Effect of Physio-ecological Factors on Photosynthesis

1-year-old Erythrophleum fordii Oliv container seedlings were observed to investigate their leaf photosynthesis and the dynamic change of environmental factors to explore the diurnal photosynthetic change,to identify the relationship between the photosynthesis and the physio-ecological factors and discover the principal factors for photosynthesis.The results showed that the net photosynthetic rate（Pn）presented a＂twin peaks＂curve and an obvious photosynthetic＂siesta＂.Diurnal change of leaf temperature（Tl）,transpiration rate（Tr）,leaf-to-air vapor pressure deficit（Vpdl） were consistent with that brought by photosynthetic active radiation（PAR）,peaking at noon.The air relative humidity（RH） was the lowest at noon.The diurnal stomatal conductance（Gs） altered over time,with three apexes in a day,peaking at 4 pm.The diurnal variation of Cidisplayed a＂double peak＂curve,and that of WUE and LUE presented ＂U＂shape.Pnof the seedlings was mainly influenced by PAR,Ca,Ta,RH,Gs,Tr,Tland Vpdl,among which PAR,Ca,Tland Vpdlwere the most.PAR was the main decision factor and the T1 was the main restricting factor.Diurnal photosynthetic change of the seedlings followed certain rules and the effect of physio-ecological factors varied.