Studies on the Developmental Physiology in Rice Pollen : I. The metabolic patterns connected with the structural changes in developing pollen

[摘要] Several investigations have been carried out on the male sterility in rice plants, especially referring to the damage in pollen by cold weather. So far results obtained, however, seem to be unsatisfactory in the developmental physiology of rice pollen which is one of the most important field. The work reported here is a part of the study to elucidate the metabolic patterns connected with the developmental phases in rice pollen. The results obtained were summarized as follows; 1. The occurrence of the unfruitfulness spikelets on the panicles in rice varieties, Kamenoo and Akaho, was encouraged by top-dressing of excessive nitrogen at the early stage of panicle formation. 2. The increment of the pollen grains in diameter was rapid at one nuclear Period (I period), but slow at binuclear period (II period) and again vigorous at trinuclear period (III period). The change in water content of anther was similar to that in the pollen diameter above mentioned. 3. The length of anther closely correlated with the developmental stages in pollen. 4. Total nitrogen content per dry weight of anther at I and II period was higher than at III period. Insoluble nitrogen (IN) content per anther increased at I period. The increment of IN at II period was slow, while the soluble nitrogen (SN) per anther began to increase since this stage. At III period, both IN and SN contents per anther increased conspicuously. On the basis of such results, it was assumed that there are three patterns of nitrogen metabolism in pollen development; the first is active protein synthesis at I period, the second is active amino -acid synthesis at II period and the third is active synthesis of both protein and amino-acid at III period. 5. Soluble and insoluble organic phosphorous contents per anther gradually increased to II period, but they decreased at III period. On the contrary, inorganic phosphorous (Pi) content per anther at III period was over three times than at II period. As a result, Pi content in anther at III period was about 60% of total phosphorous content. 6. Although there was just a trace of starch content in anther at I and II period, it increased remarkably at III period. High synthetic activity of starch at III period showed a sharp contrast to those of other periods. 7. The top-dressing of excess-nitrogen caused the high occurrence of the fruitfulness spikelets following the decrease of SN content at II period and Pi and starch content at III period in anther. 8. On the morphorogical observation in developing pollens, it was recognized that the generative nucleus was surrounded by membrane-like substance at the time of division. The characteristics of rice pollens seem to be represented by the metabolic patterns proper to one-, bi- and tri- nuclear period, and also by the presence of the membrane-like substance surrounding the generative nucleus. The morphological and physiological knowledges of rice pollens will be enriched through the elucidation of these properties of them and this effort will contribute to throw light on the mechanism of the occurrence in male sterility of rice plants.

[学科分类] 农业科学（综合）