The diurnal variation of photosynthesis of Lindera aggregata was studied by the LCA-4 Portable Photosynthesis System under natural conditions on clear days of mid-August. The results were as follows. The curve of net photosynthetic rate (P_n) in the leaves of L. aggregate under full light was bi-peak type with an obvious midday depression phenomenon at noon. The diurnal variation of internal CO_2 concentration (C_i) was opposite to P_n. The increase of C_i at midday indicated that the midday depression of the photosynthetic efficiency was mainly influenced by the non-stomatal factors. The diurnal variation of the dark respiration rate (R) was single-peak type and was the highest at midday. The optimization equation for the diurnal variation of P_n was calculated by stepwise multiple-regression method (Y=118.098 4 + 0.012 2X_1- 0.767 0X_3 - 3.231 3X_4, R= 0.987 3, F= 38.488 7, P= 0.006 8, S=0.689 7). The partial correlation and path analysis showed that the diurnal variation of P_n had significant correlationship with air temperature (T_a), photosynthetic effective radiation (PAR) and air relative humidity (RH), respectively. This indicated that PAR, RH and T_a might play important role in the P_n and ranked as T_a>PAR> RH.
Lindera aggregatanet photosynthetic rateecological factorstepwise multiple-regressionpath analysis multiple-regressionanalysis of path
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