© 1994 Heron Publishing—Victoria, Canada
Carbohydrate mobilization following shoot defoliation and decapitation in hybrid poplar
Timothy J. Tschaplinski (1) and Terence J. Blake (2)
1. Environmental Sciences Division, Oak Ridge National Laboratory, PO Box 2008, Oak Ridge, TN 37831-6034, USA / 2. Faculty of Forestry, University of Toronto, Toronto, Ontario M5S 3B3, Canada / Received May 12, 1993
Summary
The effects of shoot defoliation, decapitation, and disbudding on carbon mobilization were investigated in rooted cuttings
of Populus maximowiczii × nigra L. ‘MN9’. Ten days after complete shoot defoliation or decapitation, the stem starch concentration of treated plants declined
to one-half that of intact plants, and there were similar or greater reductions in the concentrations of glucose, fructose,
sucrose, galactose, and shikimic acid. Partial shoot defoliation (50%) and complete disbudding had no effect on stem starch
concentration, but stem sucrose concentration was reduced in all treatments. Sucrose depletion preceded and may have induced
other changes in the carbon status of plants subjected to leaf or shoot removal. Four days after shoot decapitation, the sucrose
concentration of roots of treated plants was reduced to 25% of that of intact plants. However, the concentrations of fructose
and glucose increased in the roots of treated plants and was followed by the accumulation of shikimic acid, salicyl alcohol,
unknown compound A and salicin. The possible role of increased concentrations of root organic solutes in the water relations
and regrowth process of decapitated plants is discussed.
Keywords:
carbon status, disbudding, fructose, galactose, glucose, shikimic acid, starch, sucrose.
