Abstract
Genetic analyses have been carried out for male sterility of artificial mutants induced by the gamma ray of 60Co or the chemical mutagen ethylene-imine (Table 1). Observation of pollens of male-sterile lines vegetatively propabaated by dividing tillers revealed that there were three types of pollen degeneration. They are no pollen type which does not produce any pollen grains in an anther and most frequently appeared, non-stained pollen type which produces abortive pollen grains not stained by the solution of iodine-potassium iodide and occurred with fairly high frequency, and stained pollen type with apparently normal pollen grains which appeared less frequently (Table 2). Most mutant lines were completely sterile under bagged self-pollination but three lines were partially (3 to 14%) self-fertile. When male-sterlle plants of mutant lines were pollinated with normal pollens of another glutinous cultivar, all mutant lines showed normal seed set suggesting that female organs were not spoiled and that sterility of these lines was caused by male sterility.
