基于13C示踪的2个杉木家系幼苗光合碳分配动态OA北大核心CSTPCD

[Objective]To investigate the exogenous carbon fixation and photosynthetic carbon transport and allocation in different organs of seedlings of two Chinese fir families under different CO2 concentrations,and to provide a theoretical basis for revealing the response mechanism of carbon fixation and photosynthetic carbon allocation strategy to the increase of CO2 concentration.[Method]Three CO2 concentration gradients were established:a control concentration of(400±50)μmol·mol-1(C400)and two elevated concentrations of(800±50)μmol·mol-1(C800)and(1 000±50)μmol·mol 1(C1 000)were established in the seedlings of No.020 and No.061 Chinese fir,which are extensively cultivated in the southern forest region,with the objective of quantifying the flow and distribution of fixed photosynthetic carbon in diverse tissues and organs at varying stages following tracer labeling,employing the 13C labeling method.The 13C labeling method was employed to label varying concentrations of CO2,quantify the flow and distribution of fixed photosynthetic carbon in each tissue and organ at different stages of the tracer labelling process,and analyse the net photosynthetic rate.The objective is to ascertain the proportion of biomass distributed to each organ and to elucidate the growth differences.Furthermore,the aim is to determine the differences in carbon fixation capacity and the in vivo distribution of photosynthetic carbon in seedlings of each Chinese fir family under different CO2 concentration conditions.[Result]The 13C allocation and biomass allocation ratios of all tissue organs in seedlings of each Chinese fir family exhibited a pattern of leaf＞stem＞root under different CO2 concentration treatments.As the CO2 labelling concentration increased,the net photosynthetic rate and δ1C value of each organ in seedlings of each Chinese fir family generally increased subsequently.No.020 facilitated the transfer of 13C to the roots,as evidenced by an increase in the latter.Following a 1 d treatment,the C800 and Cl 000 treatments resulted in 50.40％and 109.63％of the 13C allocation to the roots,respectively,in comparison to the C400 treatment.Following 30 d,the 13C allocation ratio of No.020 aboveground exhibited an increase of 6.23％and 6.03％in comparison to the C400 treatment,while the 13C allocation ratio of stems demonstrated a rise of 39.50％and 50.31％,respectively.The C800 and C1 000 treatments yielded statistically significant results(P＜0.05)with the 13C allocation ratio of No.061 root system increasing by 22.40％and 70.26％,respectively.Additionally,the 13C allocation proportion of stems decreased by 2.45％and 15.10％(P＜0.05),respectively,while the biomass allocation proportion of No.061 stems decreased by 12.44％.Conversely,the biomass allocation proportion of roots increased by 5.22％under the C1 000 treatment.[Conclusion]In conditions of normal atmospheric CO2 concentration,No.020 fir seedlings demonstrate a greater capacity for metabolic translocation.The elevated CO2 concentrations promoted higher net photosynthetic rates and increased photosynthetic carbon synthesis in the seedlings of the two Chinese fir.Furthermore,the accelerated downward transport of photosynthetic carbon in the No.020 fir seedlings was observed,as well as the impact of elevated CO2 on the photosynthetic carbon allocation strategies in the two genotypes of the species.The fir,with No.020 tending to store photosynthetic carbon in the aboveground parts,particularly in the stems,and No.061 tending to allocate photosynthetic carbon at the expense of the stems in order to increase root photosynthetic carbon supply.