l. The length of the mesocotyl of the seedling showed the depth of the soil under which the seed was buried. 2. The optimum depth of the seed in the soil for germination was about 0.5cm., and the seed was able to germinate at a depth of 3-5cm. below the surface. But the seed which was buried deeper than about 10cm. below the surface did not germinate at all unless it was brought back near to the surface. 3. Sometimes it was seen that some of the seeds buried in the soil 3-5cm. deep germinated and the seedlings elongated in a certain measure but they shriveled up before they reached the surface of the soil. 4. The seeds buried in the soil not deeper than about 5cm. required more time to germinate and shoot out on the surface of the soil in proportion to the increase of the depth of the soil which covered the seeds. There were also some differences between the germination force of the seeds which were buried in sandy soil and that of the seeds in red clay soil. Thus, the lack of uniformity in the rate of germination of the seeds in the field is owing to (1) the variety of the depth of the soil under which the seeds are buried and (2) the sort of the soil. 5. The seed which was harvested after perfect ripeness and stored under dry condition in a room remained viable for about 2 years, but it lost its vitality after the lapse of 3 years or more. 6. The life-span of the majority of buried seeds, was 1year, while only a few seeds barely retained their vitality for about 2 or 3 years.
メヒシバは0～1cm.の深さで最もよく発芽するが，1.5cm.以上の深さでは発芽しないと言われている．しかし斯る発芽の現象は，気象条件その他によつて左右されることも大きいのでメヒシバ防除の立場からなお研究すべき点が多い．一方雑草の分布及び其の永続性は種子の性質に関係することが大きく極めて普通なそして厄介な雑草には種子の長命なものが概して多い．本邦に於て夏季雑草の王者と云われるメヒシバについて種子の寿命を調査する事は雑草防除上必要であるのみならず生態学的にも興味ある事である．Goss(1924)は多くの種類の種子を地中に埋めて寿命を調査した．其中に分解学的にメヒシバ属に近いPanicum virgatum L. があるが，邦産メヒシバ属に就いては未だ報告を見ないようである．本実験は小島教授の指導によつた．謹んで感謝の意を表する．尚一部の実験には中園重信君の助力を得た．同君の好意に対し感謝する．
Mendeley出力
