Rinne P, Tuominen H, Sundberg B
Growth-Patterns and Endogenous Indole- 3- Acetic- Acid Concentrations in Current- Year Coppice Shoots and Seedlings of 2 Betula Species
Physiologia Plantarum: 1993 88:403-412
Apical dominance, internode elongation, radial growth and xylem cell size in coppice and apical shoots of Betula pubescens and B. pendula were determined and related to endogenous indole-3-acetic acid (IAA) levels, measured by gas chromatography-selected ion monitoring in the apical bud and at three positions along the stem. The effects of defoliation and debudding on morphological and anatomical characters and endogenous IAA levels were also investigated. The coppice shoots displayed superior stem elongation and increased branching during the initial phase of growth, after which their growth pattern was similar to that of the seedlings, however, their radial growth was greater throughout the experiment. Both plant types produced smaller-sized xylem cells at the top of the shoot than at the bottom with coppice shoots tending to form larger tracheids and smaller vessels than the seedlings. There was no consistent difference in IAA concentration between the coppice shoots and the seedlings. Defoliation and debudding reduced the IAA level in the stem within 36 h and it was still low after 25 days. Although the extent of the IAA decrease was similar in both coppice shoots and seedlings, the treatments affected the morphological and anatomical characters differently in the two plant types. The results suggest that the observed differences between seedlings and coppice shoots were not mediated through a drastic change in IAA level.
e-link to journal