思茅松干季光合生理日动态及光响应特征分析

Diurnal Change of Photosynthetic Characteristics and Response to Light Intensity of Pinus kesiya Royle ex Gordon var.langbianensis

采用L icor-6400型便携式光合测定仪测定了思茅松干季的光合作用日变化及光响应特征,分析了光合生理与生态因子之间的相互关系。结果表明:思茅松净光合速率(Pn)、蒸腾速率(Tr)和水分利用效率(WUE)的日变化均呈三峰曲线,Pn峰值分别出现在12:00、14:00和17:00,最高峰出现在光强最强、温度最高的时刻(14:00),胞间CO2浓度(C i)变化方向则相反。Pn、Tr和气孔导度(Cond)与主要环境指标光合有效辐射(PAR)、空气温度(Ta)和大气相对湿度(RH)之间的关系符合二次曲线的变化规律。Pn、Tr与PAR、Ta和RH的相关程度都达到了极显著水平(P<0.01),Cond与Ta相关程度达到显著水平(P<0.05)。PAR是影响干季思茅松Pn和Cond最主要的环境因子,而Tr是受Ta影响最强烈的生理因子。非直角双曲线拟合的思茅松光饱和点(LSP)为1 800μmol.m-2.s-2左右,表现为典型的阳性树种。

Diurnal changes of photosynthesis and light response curve of Pinus kesiya Royle ex Gordon var.langbianensis were measured with Licor-6400 in dry season,and the relationship among the photosynthetic physiological factors and the ecological factors were analyzed.The results showed that the net photosynthetic rate（Pn）,transpiration rate（Tr） and Water Use Efficiency（WUE） of P.kesiya Royle ex Gordon var.langbianensis had a diurnal change with three peaks respectively in dry season,the peaks of Pn occurred at 12：00,14：00 and 17：00 respectively when the light intensity and temperature reached the highest level（14：00）,while intercellular CO2 concentration（Ci） changed in an adverse way.The correlations between Pn and PAR,Ta,RH,Tr and PAR,Ta,RH,Cond and PAR,Ta,RH fitted quadratic curve model respectively.There was a significant positive correlation between Pn and photosynthetic active radiation（PAR）（P〈0.01）,air temperature（Ta） and relative humidity（RH）,Tr and PAR,air temperature（Ta） and relative humidity（RH）,and Cond and Ta（P〈0.05）.The same environmental factors had different effects on Pn,Tr and Cond.PAR was the most sensitive environmental factor effecting on the Pn and Cond of P.kesiya Royle ex Gordon var.langbianensis.Among the test photosynthetic parameters,Tr was the most sensitive to the Ta.non-rectangle hyperbola equation that was fitted for light response curve of photosynthesis of Pinus kesiya Royle ex Gordon var.langbianensis.The high light saturation point（LSP） about 1 800 μmol·m-2·s-1 showed as typical heliophyte,and it belongs to the high light energy potential productivity tree for its photosynthetic characteristics of high photosynthetic efficiency.