Abstract: To investigate the relationship between diurnal variation of net photosynthetic rate and canopy structure, we measured net photosynthetic rate (P_n) and canopy structure parameters \[leaf area index (LAI), mean leaf inclination (MTA), and radiation coefficient (τd)\] ofendangered plantTaxus chinensis var.mairei by Li-6400 Portable Photosynthesis System and CI-110 Canopy Analyzer. The results showed that P_n was the highest at 10:00, being 10.58 μmol·m^-2·s^-1 (female) and 8.21 μmol·m^-2·s^-1 (male) respectively. It was the lowest at 14:00, being 1.03 μmol·m^-2·s^-1 (female) and 1.54 μmol·m^-2·s^-1 (female) respectively. Thediurnal variations ofP_n was not significantly different between male and female (P>0.05). The diurnal variation of P_n in both male and female had a bimodal pattern, with a clear middaydepression. P_n differed among canopy positions. In sunny side, P_n of female was descended inorder of: distal part of upper layer>basal part of upper layer>basal part of middle layer>distal part of lower layer>distal part of middle layer>basal part of lower layer. For males,P_n followed the order: distal part of middle layer>distal part of lower layer>distal part of upper layer>basal part of upper layer>basal part of middle layer>basal part of lower layer (male). In rear side,P_n of female was descended as: distal part of upper layer>basal part of upper layer>distal part of middle layer>basal part of middle layer>basal part of lower layer>distal part of lower layer. For males,P_n followed the order: distal part of upper layer>distal part of middle layer>distal part of lower layer>basal part of middle layer>basal part of upper layer>basal part of lower layer (male). The diurnal variations of P_n were not significantly different between sunny side and rear side (P>0.05).P_n of both male and female was significantly negatively correlated withLAI (r=-0.732,P=0.000) and positively correlated with MTA (r=0.602, P=0.001) andτd  (r=0.659, P=0.000).

Key words: CH₄ emission, rice, straw returning, N₂O emission, stabilized fertilizer, yield