Abstract
Abnormal behaviors of pollen tube are known to be caused by the specific substances or by the difference of osmotic pressure between pollen tube and style in the case of self-and cross-imcompatibility. In barley plant, though independent of incompatibility, abnormal behaviors of pollen tube are also briefly reported. But in order to obtain more detailed information on this point, this investigation has been particularly fccueed on the types, frequencies and mechanism cf abnormal behaviors of pollen tube. Samples were taken from field-grown plants sown on May 25, about one month later than the usual sowing date in this district. Upon anthesis, the pistils are dusted by her own pollens and then stained by cotton blue solution after ten minutes. Directions of polien tube growth in the stigma hair are divided into two groups ; (1) normal direction, the tube pointing in the direction of ovary and usually growing downward through conducting tissue and (2) revers direction, the tube growing upward and escaping from the top of stigma hair. Shapes of top portion of pollen tubet are divided into four groups, i.e., l) normal type. 2) swollen type, the growing end of pollen, tube swells until it bursts and releases its content out of tissue, 3) running-away type, pollen tube escapes from the stigma hair through intercellular space of papillary cells or intra papillary cell without showing any enlargement of top portion, and 4) Iooping type, the tip portion100ps in the conducting tissue once or more, but normal growth continues.
