Histological Studies on Breaking Resistance of Lower Internodes in Rice Culm : I. Observation on histogenesis of elongating internodes with light and electron microscope

[摘要] Histogenesis of the 4th internode from the top of rice culm, var. Koshihikari, was observed in the rapidly elongating stage with light and electron microscope. The materials, for preparation to electron microscope, were fixed with 2-4% glutaraldehyde, postfixed with 1-2% osmium tetroxide, and embedded in Spurr's resin. Meshes were stained with uranium and lead. Proliferation and enlargement of the tissues at the base of internode bring approximately 30% increase in diameter, reduction by half in thickness of the fundamental parenchyma and duplication in total thickness of the epidermis and cortical fibers (Fig. 1). Epidermal cells, just above the intercalary meristem, differentiate to long and short cells (Fig. 3). The short cells again differentiate to silica cells, cork cells and trichomes (Figs. 4 and 5). The long cells elongate in the range of 35 mm above the intercalary meristem and attain a length of about 200μm. Cortical fiber cells divide anticlinally, periclinally and radially in the zone of intercalary meristem, and in the range of 35 mm above it, they elongate rapidly to a length of average 1.2 mm (Figs. 6-9). Meanwhile, the number of periclinal rows in cortical fibers increases from 3 to 5-7, and the cell arrangement falls into disorder by intrusive growth. The intercalary meristematic cells have dense cytoplasm, and contain a number of starch grain and osmiophilic globules, which decrease during cell elongation. Dense cytoplasm, a large number of mitochondria and ribosomes are represented by the tips of the cortical fiber cells growing intrusively (Figs. 10-13). We think, therefore, that the developmental activities of the cortical fibers are reflected in the tissue thickness, the number of periclinal rows, the degree of rows irregularity and the cell length.

[学科分类] 农业科学（综合）