Studies on Optimal Photosynthetic Biochemical Model and Photosynthetic Characteristics of Typical Plants in Karst and Non-karst Regions

Abstract:

The aim was to screen the optimal model in fitting photosynthetic CO₂response curve (A-Ci curve) of plants in different habitats, three biochemical models, including Ethier & Livingston, Ellsworth, and Sharkey model, were used to fit the A-Ci curves of 8 typical plants in karst and non-karst regions of southwest China. Then the photosynthetic parameters and their response to main environmental factors were analyzed. The results showed that Ethier & Livingston model was better than the other two models in fitting A-Ci curve of 8 typical plants, with determination coefficient (R²) from 0.98 to 0.99 (P<0.01). The photosynthetic parameters (V_cmax and J_max) fitted by Ethier & Livingston model had no significant differences between karst and non-karst native plants (P>0.05), but both of them were significantly lower than that of Eucalyptus grandis×E. urophylla. Moreover, V_cmax,25 and J_max,25 of karst and non-karst native plants were significantly correlated with air temperature and soil water content (P<0.05). However, the determination coefficients (R²) between air temperature and V_cmax,25 or J_max,25 were higher than that between soil water content and V_cmax,25/J_max,25 for all plants except of J_max,25 of non-karst native plants. Therefore, these indicated that the influence of air temperature on V_cmax,25 and J_max,25 of typical plants in this area was stronger than that of soil water content.