不同生境下的象头花光合生理特性探究

Effects of different habitats on the photosynthetic characteristics of Arisaema franchetianum Engl.

以象头花(Arisaema franchetianum Engl.)为研究对象,对林缘、林下两种生境中其光合特性进行对比研究,探究象头花对不同生境适应和响应机制。用便携式光合仪Li-6400XT测量两种生境中象头花的光响应曲线,并采用5种光响应模型对其进行拟合,结合测定不同生境下的环境因子及植株长势。结果表明:(1)两种生境中象头花光响应曲线的最适模型均为改进指数模型(2)林缘、林下的光饱和点(LSP)分别为516.405μmol·m^-2·s^-1、638.500μmol·m^-2·s^-1,最大净光合速率(Pmax)分别为4.290μmol·m^-2·s^-1、6.740μmol·m^-2·s^-1;(3)两种生境中象头花叶片的气孔导度(Cs)、蒸腾速率(Tr)、空气温度(Tair)、样品室相对湿度(RH-S)和胞间CO2浓度(Ci)与净光合速率(Pn)相关性极为显著(P<0.01);(4)林缘、林下两种生境中的自然环境因子温度、湿度未见显著差异(P>0.05),仅林缘光照显著高于林下光照(P<0.05),但林下植株长势更好。得出如下结论:象头花为阴生植物,适于在林下生长,在实际的自然栽培中林下光照(0.28±0.17%)可作为遮光种植的初步参照。

We took Arisaema franchetianum Engl. as research object to analyze the response and adaptation mechanism under different habitats by comparing photosynthetic characteristics in under-canopy and gap edge. Li-6400XT, a portable photosynthesis system, was used to measure the photosynthetic light response, and its photosynthesis was fitted by five models. Environmental factors and plant growth were also measured. Results were as follows.(1) The modified exponential model was the optimal model for light response curve in under-canopy and gap edge.(2) The light saturation point (LSP) was 516.405 μmol·m^-2·s^-1 and 638.500 μmol·m^-2·s^-1 respectively in under-canopy and gap edge. The maximum net photosynthetic rates (Pmax) were 4.290 μmol·m^-2·s^-1, 6.740 μmol·m^-2·s^-1 respectively.(3)Pn was obviously related to conductance to H2O (Cs), transpiration rate (Tr), air temperature (Tair), relative humidity in the sample cell (RH-S), intercellular CO2 concentration (Ci)(P<0.01).(4) In comparison with under-canopy and gap edge, temperature and humidity showed few differences (P>0.05), light intensity in under-canopy was significantly higher than gap edge (P<0.05), while plant grew better in gap edge. The results imply that Arisaema franchetianum Engl. is a shade plant and gap edge is optimal environment. In natural cultivation, the light intensity (0.28±0.17%) in gap edge can be the initial reference to shading cultivation.