耐陰性の生理学•生態学的解析

Abstract

1. One of the causes of shade intolerability in Helianthus annuus was the increase of C/F ratio (non-photosynthetic system/photosynthetic system) with shading. The value of C/F ratio is determined as a result of the distribution of photosynthate into the photosynthetic system and non-photosynthetic system. In H. annuus, shading decreased the distribution ratio to the photosynthetic system markedly, or increased the differential C/F ratio.2. In the deeper shade was larger the proportion in dry weight of dead parts, which mainly consisted of leaves, to the whole plant. The plants grown under the 5 and 10% light conditions could not enough replace the senescent leaves with the new ones.3. The total photosynthesis under various light intensities of H. annuus was calculated with photosynthetic activity and leaf area, and the value was compared, on the basis of matter-reproduction formula, to the gross production calculated as the sum total of apparent growth of plant organs, respiration and dead parts. 4. The proportion of investment of gross production to the construction and maintenance of the photosynthetic and non-photosynthetic systems was calculated. The investment of gross production into the photosynthetic system was evidently depressed with shading.5. Comparison of growth among H. annuus, Phaseolus aureus and Impatiens parviflora suggested that the degree of shade tolerance closely related with the feature of photosynthate distribution into the photosynthetic system.