Analysis on the Bending Response of Rice Tillers to the Upright Position

[摘要] We studied how the tiller axes move toward the upright positon using one of the Japonica type rice Sasanishiki (Oryza sativa L.). In the first trials, each plant was grown in a pot. The tiller shoots were sampled at the 11th leaf-stage and at 10 days after the panicle heading. The curvature of each pulvinus was measured and indicated as a degree angle. Maximum angle of 28.4 degrees was found in the pulvinus positon 0 located at the base of a lowest internode among elongated internodes in the tiller stem. Then, the curvature of each pulvinus at the positon -1, +1 and -2 was 14.0, 12.7 and 10.9 degree angle, respectively. The curvature of the lower primary tillers of a main stem was greater than those of the upper tillers. The number of pulvini curvatured was also greater in the lower ones. This shows that pulvini of the lower primary tillers were successively responding to gravity more than one time and restored their shoots to the upright position. Almost the same results are obtained in the field experiment where the seedlings were transplanted at the rate one per hill and 5 per hill in both the space of 30×30 cm and 30×15 cm, respectively. In conclusion, it was found that the pulvini at and around the position 0 plays an important role to allow tiller axis to move into the upright position.

[学科分类] 农业科学（综合）

[关键词] Curvature;イネ;Gravitropism;屈曲;Pulvinus;ササニシキ;Rice;重力屈性;Sasanishiki.;葉枕.