Growth Rate and Shoot : Root Allometry in Pseudotsuga menziesii (Mirb.) Franco and Pinus contorta Dougl. Seedlings Raised under Two Photoperiodic Regimes

Six provenances of both Pseudotsuga menziesii (Mirb.) Franco and Pinus contorta Dougl. from a range of locations in the interior of British Columbia between latitudes 49 degrees and 58 degrees were grown for 80 days in controlled environment chambers programmed to provide daylengths comparable with those at either latitude 48 degrees, or latitude 58 degrees, during the period from mid-June to early September. Neither shoot : root ratio nor whole plant dry weight of P. menziesii were affected by photoperiod. However, P. contorta seedlings, which unlike P. menziesii set bud during the experiment, had a greater dry weight and a higher shoot: root ratio (p<0.05) under longer daylengths. The results appear relevant to the interpretation of effects of cross-latitudinal provenance transfer on plantation productivity.