Temperature and Time-Related Variation of Root Growth in Some Conifer Tree Species

1990

S. 1192-1199

2 Abb., 3 Tab., zahlr. Lit. Ang.

Unselbständiges Werk

200088919

The variability of root growth potential of cold-stored (2C) bare-root and container-grown stock of Abies grandis (Dougl.) Lindl., A. amabilis (Dougl.) Forbes., Picea sitchensis (Bong.) Carr., Pseudotsuga menziesii (Mirb.) Franco, Thuja plicata Donn, and Tsuga heterophylla (Raf.) Sarg. was tested under four air temperature regimes for 7 and 14 days. In P. menziesii, P. sitchensis, and T. plicata, root growth was greatest under the 25:20C (light:dark) regime, whereas the 30:25C (light:dark) regime was supraoptimal for all species. Temperatures cooler than 25.2OC (light:dark) were optimal for T. heterophylla and A. amabilis. A 14-day test duration consistently produced more roots than the 7-day test. Container-grown seedlings produced more new roots than bare-root seedlings. Except for P. sitchensis and T. plicata, light was required for root growth. The effect of test conditions on root growth is discussed with respect to a possible relationship between temperature optima for root growth and current photosynthate production. High within-test variability and inconsistent ranking of seed lots under different test temperatures and durations suggest that stock quality interpretations based solely on root growth potential tests should be questioned.