Effect of boron application on tree form and growth in young Pseudotsuga menziesii trees at montane sites in the South Island of New Zealand

摘要: Pseudotsuga menziesii (Mirbel) Franco (Douglas-fir) is a preferred timber species for sites in the South Island of New Zealand above about 500 m elevation where precipitation exceeds 800 mm. However young stands often exhibit leader tip death, break and stem distortion that result poor tree form. These symptoms may be caused by chemical factors such as boron deficiency or environmental frost, snow, wind, insects disease. Trials were installed two Douglas-fir at Lake Hill Rakaia Valley (570 elevation) Balmoral Station Mackenzie Basin (870 to determine if form could improved applying hydrated sodium calcium borate hydroxide (ulexite). Stem malformation (stem forking multi-leadering) was 48% 88% respectively. not reduced application Balmoral, only highest rate (32 kg B ha -1 ), which also greatly volume growth. results indicate due deficiency. Boron applied 4 significantly increased growth Hill, but higher rates both sites. 1 – 2 more appropriate Douglas-fir. This study indicates foliar concentration 12 mg adequate good Douglas-fir, optimum It concluded further studies are needed better understand link between climate montane environments, well relationships application, different environments.