暖地型イネ科牧草の採種に関する研究 : II.グリーンパニックの出穂・登熟からみた採種適期の判定

抄録

In order to establish proper method of harvesting seed of Green panic (Panicum maximum var. trichoglume), an experiment was conducted to clear the processes of the heading, seed ripening and shattering in this grass. 1) The maximum rate of heading was observed at about 3 weeks after the heading began, and before this time large-sized heads almost emerged (Fig.2). 2) A survey of the blooming pattern in a head was carried out. The blooming occurred night ; starting from 9 p.m. and most frequently until 11 p.m. (Fig.3). It started from the uppermost spikelet in a head, and from the uppermost floret in each spikelet and proceeded downward. The blooming was kept up for about 7 days per head, and lasted for about two hours per floret. 3) On the 9th day after the blooming started in a head, the shattering of the florets was first observed, and on the next day (10th day) it increased up to 30% of the total florets in a head. Although the shattering did not occur in a few days thereafter, it increased rapidly again (Fig.5). The former heavy shattering until the 10th day after the blooming seems to be affected by the climatic conditions, especially such as rain and wind (Fig.4), but the latter increase might be inevitable in the ripening process (Fig.5). 4) Seeds thinner than 0.50mm were not able to germinate, and in case of seeds thicker than 0.51mm, the thicker seeds showed the higher rate and percentage of germination (Fig.6). These results could suggest that when the seed crop is harvested from large-sized heads which constitute the first maximum rate of heading and when the seed shattering proceeded to about 30% loss of the whole florets, the highest seed yield of good quality will be obtained.