GROWTH AND FORM OF WESTERN LARCH STECKLINGS - PLAGIOTROPISM AND REITERATION

Western larch (Larix occidentalis Nutt.) in the interior northwestern United States produces small and infrequent cone crops resulting in re current seed shortages throughout much of its range. Vegetatively prop agated planting stock could potentially alleviate shortages of seedlin gs for artificial regeneration. In a greenhouse study to evaluate suit ability of rooted cuttings for forestry, morphology and growth of cont ainer-grown stecklings from 1- and 3-year-old ortets were compared wit h seedlings for up to 6 years after rooting. Newly rooted stecklings p roduced an average 50% orthotropic, 32% plagiotropic, and 18% suppress ed leaders. One-year-old steckling leaders elongated 46% as long as 1- year-old orthotropic steckling leaders after fertilization with 20:20: 20 N-P-K at 120 ppm N (p = 0.0001). In subsequent years, orthotropic s tecklings elongated more than seedlings. Plagiotropic leaders (average deflection of 24 degrees) developed upright form within 2 years. Comp eting axillary shoots delayed development of dominant leaders for up t o 3 years. Vestiges of atypical habit included small basal stem crooks and sparse branching. Although staking and pruning promoted excurrent habit, poor quality of container-grown stecklings can limit indoor nu rsery production. Effects of ortet and environment on quality should b e examined before stecklings are field tested for use in reforestation .