方翅网蝽对两种类型悬铃木光合作用的影响

Influence of Corythucha ciliate hazards on photosynthesis of two types of Platanus acerifolia

于2010年4—8月通过对两种不同类型悬铃木的叶片净光合速率、叶绿素含量和方翅网蝽危害程度进行了测定,并运用多元逐步回归和通径分析方法分析了光合作用与环境因子之间的相互关系。结果表明,虫口密度与叶绿素含量呈负相关关系,且不同类型悬铃木间叶绿素含量差异显著;方翅网蝽危害使叶绿素含量减少是影响光合作用的最直接和最重要的原因。生长季节各月所选典型天气下的Pn大小顺序表现为7月>8月>6月>5月>4月;其中4、5月悬铃木净光合速率(Pn)日变化呈现"单峰"曲线,经分析发现大气温度、光合有效辐射、气孔导度是影响Pn变化的主要因子;6—8月Pn日变化呈现"双峰"曲线,环境因子大气水汽压差、相对湿度和胞间CO2浓度成为主要影响因子。由此可见,悬铃木生长季节光合作用存在较大差异,同时各环境因子对光合作用的影响及影响程度也各不相同。

From April to August in 2010,the diurnal and seasonal dynamics of the net photosynthesis rate,the chlorophyll content and the degree of Corythucha ciliata hazards in two types of Platanus acerifolia were determined and the relationships between the dynamics and environmental factors were analyzed by the stepwise multiple regression and the path analysis.The results showed there was a negative relationship between the insect density and the chlorophyll content and the chlorophyll content was remarkably different between the two types of P.acerifolia.The reduction of chlorophyll content in the leaves resulted from C.ciliata hazards was the most directly and the most important reason for affecting the photosynthesis.The daily mean net photosynthesis rate（Pn） for each month was in the order of JulyAugustJuneMayApril.The diurnal change of Pn was a ＂one peak＂ curve in April and in May respectively,while it was a ＂two peaks＂ pattern in June to August.The dynamics of Pn was very sensitive to the air temperature,photosynthetic active radiation and stomatal conductance in April and May,and to vapor pressure deficit,relative humidity and Ci in June,July and August.It was suggested that there existed greater differences in the diurnal and seasonal dynamics of Pn in the growth period of Platanus acerifolia,and the effects of the environmental factors on Pn were different.