Abstract
Growth angles of inclination of primary seminal roots for 133 Japanese wheat varieties were examined in an agar medium. Germinated seeds were set on a 0.2% agar medium and the initial emergence directions of the primary seminal roots were adjusted horizontally. Two days after setting, growth angle of inclination, defined as the angle between the root growth direction and the horizontal direction, was measured with a protractor. Root geotropic responses of the varieties were represented by the values of the growth angles of inclination of the roots. Varietal variation was found in the growth angles of primary seminal roots. The inclination angles ranged from the smallest, 4 °for Minaminokomugi, to the largest, 64°for Norin 58. Varieties which were bred in the northern part of Japan had large root growth angles and varieties which were bred in the southern part of Japan had small root growth angles. Prostrate-type or high degree of winter habit varieties had large root growth angles. On the other hand, erect-type or low degree of winter habit varieties had small root growth angles. As results of an additional experiment, no significant difference in root elongation rates and in root diameters was found between Minaminokomugi and Norin 58.
