散射辐射比例与冬小麦光能利用率和总初级生产力的关系

Relationships between Diffuse Radiation Fraction and Light Use Efficiency and Gross Primary Productivity of Winter Wheat

利用冬小麦拔节-乳熟期(2004-04-01—05-20和2005-04-10—05-31)在田间观测的每30min涡度相关和小气候数据,计算散射辐射比例(DF)与光能利用率(LUE)和总初级生产力(GPP)之间的数量关系,以期为提高LUE模型和作物模型的模拟准确度提供依据。结果表明:冬小麦拔节-乳熟期DF与LUE间呈极显著的线性正相关关系(P<0.001),DF与GPP间为极显著的抛物线关系(P<0.001),即随着DF的增加,LUE呈线性增长,而GPP呈先增加后降低的变化趋势。2004年和2005年观测实验表明,中等太阳辐射条件下,即DF和光合有效辐射(PAR)的均值分别为0.57和27.7mol?m-2?d-1时,冬小麦GPP达到最高。2004年与2005年相比较,DF与LUE、DF与GPP关系均存在较大差异,这主要归因于两年间冬小麦拔节-乳熟期PAR水平和DF分布频率的差异。

The quantitative relationships between the diffuse radiation fraction （DF） and light use efficiency （LUE） and gross primary productivity （GPP） from jointing to milky maturity of winter wheat （from April 1, 2004 to May 20 and from April 10, 2005 to May 31） were analyzed in this research on the basis of field CO2 flux observation. The research results can improve the simulation accuracy of LUE model and crop model. The results indicated that the relationship between DF and LUE was significantly positive linear （P〈0.001）, and the relationship between DF and GPP was significantly parabolic curve （P〈0.001）. LUE increased linearly with the increasing of DF, while GPP increased first and then decreased. Observational experiments on 2004 and 2005 showed that the GPP of winter wheat reached the highest under the condition of moderate solar radiation, with the average values of DF and photosynthetic active radiation （PAR） were 0.57, 27.7mol×m^-2×d^-1, respectively. The quantitative equations between DF and LUE and GPP in two years were different. The differences were mainly attributed to the different PAR level and the distribution frequency of DF from jointing to milky maturity of winter wheat during the two years.