菲油果光合特性的日变化

Diurnal variation of photosynthetic characteristics in pineapple guava

利用Li-6400便携式光合测量系统对Coolidge菲油果的叶片净光合速率(Pn)等指标进行了测定,并通过多元逐步回归分析和通径分析方法探讨净光合速率与影响因子的关系.结果表明:菲油果叶片净光合速率日变化曲线为双峰型,在11:00和16:00分别出现1次高峰,具有典型的午休现象;影响菲油果叶片净光合速率的主要因子是空气相对湿度(RH)、蒸腾速率(TR)、气孔导度(GS)和胞间CO2浓度(Ci),叶面温度(Tl)、光合有效辐射(PAR)和大气CO2浓度(Ca)的影响相对较小.净光合速率与主要影响因子的多元回归方程为:Pn=22.63743-0.1651Tl-0.1622PAR-0.0016RH+0.2539Ca+8.18585GS+1.1276TR-0.04445Ci(R2=0.943).

The diurnal variations of photosynthesis on the pineapple guava （Feijoa sellowiana Berg. cv. Coolidge） were studied under the same natural conditions by using a Li-6400 portable photosynthesis system, and the relationship between net photosynthetic rate （Pn） and its physio-ecological factors including PAR, RH, T1, Ca, GS, Ci and TR etc. were clarified by path analysis and stepwise regression equation. The results showed that the curve of diurnal variation of Pn demonstrated two peaks in clear day, which appeared at 11：00 and 16：00, respectively. There was a clear depression at noon. Among the ecological factors, RH was the major one that influenced the variations of Pn, and TR, GS and Ci were three key physiological factors that influenced the variations of Pn. The correlation equation between Pn and the major physio-ecological factors was Pn=22.637 43-0.165 1T1-0.162 2PAR-0.001 6RH＋0.253 9Ca＋ 8.185 85GS＋1.127 6TR-0.044 45Ci（R^2=0.943）.