利用13C和15N示踪碳、氮在栓皮栎幼苗各器官中的分配
Carbon and Nitrogen Allocation in Organs of Quercus variabilis Seedlings by 13C and 15N Tracer Technique

通过对盆栽栓皮栎幼苗进行13C和15N稳定同位素双标记,探究碳、氮素在栓皮栎幼苗各器官中的流动及分配模式。结果表明:(1)在进行13C标记之前及标记7 d之后,叶片、细枝、粗枝、细根、粗根这5类器官之间的13C丰度显著差异(P＞0.05)。(2)在标记后2 h,约81.97 %的13C量分配到叶片中,之后叶片中13C量逐渐降低,而其他4类器官中13C量大体呈现出先随时间递增而逐渐升高,随后稳中下降的趋势。标记后1个月,各器官中13C分配比例分别为:叶片(25.46±6.50)% 、细枝(7.69±1.47)% 、粗枝(24.38±3.59)% 、细根(12.04±3.88)% 、粗根(30.44±6.37)%。(3)15N在植株中分配稳定后,各器官中15N丰度表现为:叶片＞细根＞细枝＞粗枝＞粗根,但彼此之间差异并不显著(P＞0.05)。15N在各器官中的分配比例分别为:叶片(45.34±2.75)%、细枝(5.36±0.46)%、粗枝(14.70±0.56)%、细根(3.96±0.94)%、粗根(30.64±1.55)%。总之,栓皮栎幼苗吸收的“新碳”和“新氮”会流向整个植株体,光合产物在各器官的分配有一定的时差,其中,最优先分配到叶片,然后逐渐分配到其他器官当中；分配稳定后,各器官标记稳定同位素之间差异不显著,表明各器官之间稳定同位素分馏作用不明显。而“新碳”和“新氮”在各器官中分配比例的差异,主要是由各器官生物量差异所致。
The experiment explored the flow and distribution patterns of C and N in different organs of potted Quercus variabilis seedlings with 13C and 15N isotope labeling techniques. The results indicated that:(1)Before and 7 days after 13C isotope labeling,there were no significant differences in 13C abundance among leaves,fine and coarse branches,fine and coarse roots (P＞0.05).(2)Two hours after labeling,about 81.97% of labeled 13C was distributed to leaves,then the 13C content in leaves gradually reduced,and in other 4 organs,the amount of 13C first gradually increased with time and then decreased steadily. One month after labeling,13C allocation proportions in organs were as follows:leaf(25.46±6.50)%,fine branch (7.69±1.47)%,coarse branch (24.38±3.59)%,fine root (12.04±3.88)%,coarse root (30.44±6.37)%.(3)After 15N was stably distributed in plants,the abundance of 15N in all organs showed leaf ＞ fine root ＞ fine branch ＞ coarse branch ＞ coarse root,but there was no significant difference among them (P＞0.05). The allocation proportion of 15N in each organ was:leaf (45.34±2.75)%,fine branch (5.36±0.46)%,coarse branch (14.70±0.56)%,fine root (3.96±0.94)%,coarse root (30.64±1.55)%. In a word,the "new carbon" and "new nitrogen" absorbed by Quercus variabilis seedlings would flow to the whole plant. The distribution of photosynthetic product in the organs showed a time dependant pattern,and it was first assigned to the leaves,and then gradually assigned to other organs. After stably being distributed,the abundance of the stable isotope was not significantly different among organs,which indicated that the stable isotope fractionation between different organs was not obvious. The difference of the proportion of "new carbon" and "new nitrogen" in different organs was mainly caused by the difference of biomass of each organ.