Abstract
Varietal differences in the number of stigma-hairs and the effect of cold treatment oll the character were studiecl in several Japanese paddy rice varieties ancl in the F2 of the hybrids between the vafieties Kinmaze and Somewake. ' As it ¥vas difficult td count the number of stigma-hairs uncler a microscope, stigmas wer'e' reconstructed from serial transverse section. The length of both arither and stigma was less by ten percent tharL that 0L the control aLter cold treatment (day temperature 17'C and night temperature 12'C for 5 days) at the meiotic stage. Two fl6ral characters (anther ancl stigma length) of the control and plants subjected to the cold treatment were both negatively correlated with the sterility index, arcsin /percent of sterility
