グラジオラス球茎の形成, 肥大に関する組織学的研究

Abstract

The process of development of gladiolus corms was studied by histological procedures.Cormlets of cv. ‘Traveller’, the average weight of which was about 0.3g, were planted on April 22, and were sampled at weekly intervals until September 11. At each sampling date, a batch of 10 corms was fixed and examined microscopically.The results of investigations are summarized as follows:1. In the rest period, the mother cormlet had three sheath leaves and one foliage leaf of 1-1.5mm long in its main bud. After growth of one week, origination of daughter corm was brought about by the thickening growth of internodes between the outermost sheath leaf and the first foliage leaf.2. In early stage of growth, for 9 weeks after planting, the development of daughter corms depended mostly upon cell multiplication in cortex and stele. In the next stage, from the 9-th to the 14-th week after planting, thickening growth was caused by cell division in the cortex and cell enlargement in cortex and stele. After the 14-th week, in the third stage, corm enlargement was mainly depended upon enlargement of cells in the cortex.3. Increase in the number of cells at the initial stage of corm development was brought about by the activity of the apical meristem. On the contrary, successive thickening growth was caused by actively dividing cells which diffused in permanent tissues of daughter corms. Both chromosomes and storage starch grains were found simultaneously in the mitotic cells. These dividing cells did not form any meristematic tissue, but diffused in permanent tissues of cortex and stele.4. These facts show that the pattern of thickening growth of gladiolus corms is “diffuse thickening growth”, which is one of the thickening growth patterns observed in monocotyledons.