Effect of Different Photon Flux Densities (PAR) on Seedling Growth and Morphology of Metrosideros collina (Forst.) Gray

Abstract

Seedlings of Metrosideros were capable of net accumulation of dry matter at photon flux densities as low as 13 umol m-2 s-1 PAR (about 0.6 percent sunlight), when grown under a 12-hour day1ength at 20° or 25°C for over 4 months. Seedlings became adapted to shade at low levels of PAR by an increased leafiness of the plant (expressed as the leaf area ratio). This increased leafiness was brought about by a marked reduction in leaf thickness rather than by an increase in the proportion of assimilates distributed to leaves.