Photosynthetic functions and chlorophyll fast fluorescence characteristics of five Pinus species

A comparative study was made on the needle morphological characteristics,photosynthetic rate,and chlorophyll fast fluorescence induction curves of five representative Pinus species P.parvifiora,P.armandii,P.bungeana,P.tabuliformis,and P.densiflora.Significant differences were observed in the needle morphological characteristics among the five species.P.tabuliformis had the longest needle length and highest needle density,whereas P.bungeana had the highest chlorophyll content.P.densiflora and P.parvifiora had the maximum and minimum photosynthetic rate,respectively.There was a positive correlation between the photosynthetic rate and stomatal conductance across the five species.The differences in the chlorophyll fast fluorescence induction curves of the five species were mainly manifested in J-step and I-step.Although the five species had similar values of Fv/Fm,Fv/Fo and Tfm,P.parvifiora had significantly higher values of dV/dto,dVG/dto,Vj and Vi,but lower energy flux ratio ψo,φEo and φRo,compared with the other four species.The low PSII activity and efficiency of P.parvifiora might relate to its smallest Sm,Sm/Tfm and N.P.densiflora and P.parvifiora had the maximum and minimum vitality indices PI(ABS/CSo/CSm) and DF,respectively,and there existed significant positive correlations between the PI(CSo) and PI(CSm) and the net photosynthetic rate of the five species,suggesting that PI(CSo) and PI(CSm) could be used to estimate the photosynthetic activity of Pinus trees.