Secondary Branch Angles and Potential Topophytic Effects of Vegetatively Propagated Clones of Taxodium
| Autor: | Andrew R. King, Michael Arnold, W. Todd Watson, Douglas F. Welsh |
|---|---|
| Rok vydání: | 2013 |
| Předmět: | |
| Zdroj: | Journal of Environmental Horticulture. 31:84-88 |
| ISSN: | 2573-5586 0738-2898 |
| DOI: | 10.24266/0738-2898.31.2.84 |
| Popis: | Baldcypress [Taxodium distichum] branch angles were measured between the primary leader (1st order) and second order branches at three different positions (low, medium, high) in the canopy of 828 four-year-old, field-grown seedlings. Seedlings represented twenty-three open-pollinated families collected from Central Mexico to Alabama. Based on these measurements, six different representative families (three families with the most acute branch angles and three families with the most obtuse branch angles) were chosen to test 1) whether topophysis significantly affects the orientation and/or growth of ramets and 2) if branch angle divergence from the trunk of the ortet impacts the degree of topophysis observed on the ramets from rooted shoot tips. Cuttings from the six seedlings were harvested in June 2008 from basal (more horizontally oriented branches) and terminal (more erect upper branches) portions of the canopies in order to test topophytic effects. Rooted cuttings were oriented vertically upon transplanting and grown for approximately 8 months. Measurements included initial and final height and stem diameter and the final angle between the primary leader and the substrate surface. Branch angle data collected from field-grown seedlings revealed a significant interaction (P ≤ 0.0001) between family and location within the canopy. Most families measured had branch angles that were most obtuse at the bottom of the canopy becoming progressively more acute toward the tree apex. MX6D, TX3D, TX6D and EP7D were families that exhibited minimal to no branch angle differences in regard to position within canopy. Data analysis showed no significant main effect or interactions of cutting location within the canopy on vertical orientation during container production. A significant main effect (P ≤ 0.0001) of clone was observed for all measurements except initial stem diameter. Clone MX2MC31 cuttings displayed the greatest mean angle of divergence from vertical at 48° while cuttings of MX6MC14 diverted ≈12° from vertical. In this study neither initial branch angles on the ortet nor position within the canopy from which cuttings were taken was an accurate significant predictor of cutting orientation relative to vertical. Tendencies for clonal differences in vertical growth however, suggest the potential for selection of baldcypress clones that would have a reduced need for staking during production. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|