The Carbohydrate Resources of Young Apple-trees under Four Levels of Illumination

Abstract

Young apple-trees were grown in four light intensities to assess the differentia dependence of growth on reserve carbohydrates and current products of photosynthesis. Low light intensity caused no greater depletion of reserve carbohydrates during initial growth in spring, and during the growing season a similar composition was maintained with all treatments despite large differences in dry-weight increment. The results suggest that there is an ‘integrated phase of growth’ during which carbohydrate composition is independent of external factors, and which may be followed by a ‘labile phase’ during which accumulation of reserves can be influenced.