Dickson R E
USDA Forest Service, North Central Forest Experiment Station, Forestry Sciences Laboratory, P.O. Box 898, Rhinelander, WI 54501, USA.
Tree Physiol. 1987 Jun;3(2):157-71. doi: 10.1093/treephys/3.2.157.
Diurnal changes in concentrations of leaf chemical fractions and partitioning of photosynthetically fixed (14)C within the plant and among chemical fractions were studied in rapidly growing cottonwood (Populus deltoides Bartr. ex Marsh.) seedlings. During the light period, leaf weight (mg cm(-2)) increased by about 25% primarily as a result of the accumulation of starch and sucrose, and to a lesser extent because of an increase in the content of amino acids and the chloroform fraction (pigments plus lipids). In contrast, reducing sugars and organic acids decreased in concentration. The partitioning of (14)C within the plant also changed during the light period. Acropetal transport to developing leaves and stem decreased from 81 to 55% of the total (14)C translocated from a source leaf in 4 hours, whereas basipetal transport to stem and roots increased from 13 to 37%. Although assimilation rate ((14)C fixed in 0.5 h) remained constant during the light period, the percentage of fixed (14)C translocated out of the source leaf in 4 h decreased from 27 to 9%. This change in transport rate of recently fixed (14)C was caused by a shift in (14)C partitioning from transport sucrose to storage starch. During the light period, the incorporation ratio ((14)C-sugar/(14)C-starch) decreased from 40 at 0700 h to 2 at 1900 h. The partitioning of carbon to different chemical fractions within the source leaf and the interactions or feedback between different sinks and the source leaf have a major influence on plant growth and development. Control of this carbon partitioning is located in both source and sink leaves.
在快速生长的杨树（Populus deltoides Bartr. ex Marsh.）幼苗中，研究了叶片化学成分浓度的日变化以及光合固定的（14）C在植物体内和化学成分之间的分配情况。在光照期间，叶重（mg cm(-2)）增加了约25%，主要是由于淀粉和蔗糖的积累，其次是由于氨基酸和氯仿部分（色素加脂质）含量的增加。相比之下，还原糖和有机酸的浓度降低。（14）C在植物体内的分配在光照期间也发生了变化。向发育中的叶片和茎的向顶运输从源叶在4小时内转运的总（14）C的81%降至55%，而向茎和根的向基运输从13%增加到37%。尽管同化率（0.5小时内固定的（14）C）在光照期间保持不变，但4小时内从源叶转运出的固定（14）C的百分比从27%降至9%。最近固定的（14）C运输速率的这种变化是由于（14）C分配从运输蔗糖转向储存淀粉所致。在光照期间，掺入率（（14）C-糖/（14）C-淀粉）从0700时的40降至1900时的2。碳在源叶内不同化学成分之间的分配以及不同库与源叶之间的相互作用或反馈对植物的生长和发育有重大影响。这种碳分配的控制位于源叶和库叶中。
