Abstract
To clarify the occurrence of sterility in rice plants and its varietal differences in rice plants grown under the condition of cold water irrigation, investigations were conducted by using four varieties which have different resistabilities against cold water irrigation. Having established plots of four different water temperatures, ranging from low to nearly optimum, the author examined the number of pollens adhered on the stigma and pollen germination on it. In addition to this, he observed both developments of anthers and pollens involved in them during the period of flower development. Main results were as follows : 1) Low water temperatures give rise to less pollens adhering on the stigmas. Resistabilities of varieties against cold water irrigation were correlated positively with numbers of pollens on the stigma. 2) It is inferable that there might be less significant difference in pollen germination between both warm and cold plots. 3) Damaged plants due to cold water irrigation bore anthers of smaller size as compared with those of non-damaged.
