一年生アカマツ苗の生長と菌根形成に影響する日長および温度条件について

Abstract

1)The growth of tops and roots, and the morphology and occurrence of mycorrhizal short roots were investigated using the first year seedlings of Pinus densiflora under controlled environmental conditions including length of day, temperature and their combinations. 2) The elongation of shoot was hastened by longer day length but the increase in dry weight by greater quantity of light accepted by the plants.3) The onset of the shoot elongation, especially under shorter day length, began earlier at 30° than at 20°.4) Almost all of the short roots seemed to be mycorrhizal.5) The short roots were exclusively borne on the distal parts of long roots, then the number of short roots was determined by the number of long roots.6) The number of long and short roots was larger under continuous light than under light-break treatment as well as under short day. Accordingly the formation of mycorrhizal short roots do not depend on day length but depends on the quantity of light accepted by the plants.7) Some temperature effects were seen on the production of short roots; in the seedling at ealier stages of development the short roots were abundant at 20° than at 30°. At later stages they were somewhat invariably produced at 20° under continuous light and short day, but at 30° abundantly produced under the former condition.