Tetsuya Kondo

Hokkaido University | Hokudai · Research Faculty of Agriculture

Seeds with deep simple double morphophysiological dormancy (MPD) need cold stratification during the first winter after dispersal for radicle emergence, followed by the summer for root and bud development and finally a second winter for shoot emergence. In a previous study, we demonstrated that Trillium camschatcense seeds have this type of dormanc...

Papaver fauriei is an endemic and endangered species that grows only on the gravelly alpine slopes of Mt. Rishiri, Japan. Cultivated poppy (Papaver sp.), the species name of which is unknown, has been introduced to the natural habitats of P. fauriei through human activities. Because the appearance and internal transcribed spacer (ITS) sequences of...

Convallaria majalis has double dormancy and hypogeal germination, but no information is available on embryo growth or on the effects of light and gibberellic acid (GA3) on germination in this genus. Therefore, we investigated embryo growth and other germination features in seeds of C. keiskei and compared the data with those of Trillium camschatcen...

Convallariamajalis has double dormancy and hypogeal germination, but no information is available on embryo growth or on the effects of light and gibberellic acid (GA3) on germination in this genus. Therefore, we investigated embryo growth and other germination features in seeds of C. keiskei and compared the data with those of Trillium camschatcens...

The life history and effects of sowing time on the germination of cultivated poppy growing in towns of Rishiri Island were investigated in Sapporo.

Seeds of cultivated poppy maintain their initial germinability for 6 years when stored at 5°C or freezing condition.

We in vestigated the effects of mowing on the growth of Rudbeckia laciniata L., an invasive alien species in Japan, and discussed the possibility of eradicating this species by this method. Seedlings of R. laciniata were cultivated in pots, and the time from seed sowing until flowering was examined. Further, the effect of eight mowing treatments wi...

In previous studies, seeds of Weigela hortensis K. Koch had high germination rates in light but did not germinate or only germinated less than a few percent in darkness, even after cold stratification. However, those studies were conducted under experimental conditions in relatively narrow range. If we can work out how to germinate seeds of W. hort...

To determine the traits of seed propagation of the black locust, an invasive woody legume, in northern Japan, we studied the development process of black locust seeds by phenological observation and by physiological and anatomical analyses. We collected seeds from two mother trees at several times between August and March in 2007-2009. From each tr...

Seeds with epicotyl dormancy reside in soil up to 15 months (or longer), being exposed to a sequence of temperatures, before seedlings completely emerge (i.e. with both roots and shoots). Heretofore, few studies have examined precise temperatures, especially in sequences, for promotion of radicle and cotyledon emergence and how they relate to envir...

We investigated the germination characteristics of Rudbeckia laciniata L. seeds and whether or not they form a seed bank. On the basis of our results, we discuss the mechanism of seed bank formation. In laboratory experiments using incubators and Petri dishes, we investigated the effects of light, alternating and constant temperatures, cold stratif...

We studied the effects of cold stratification, light, temperature, pericarp, storage, and burial depth on germination of Glehnia littoralis seeds, and temperature requirements for embryo growth. Radicles emerged from fewer than 2% of fresh seeds regardless of light condition or temperature. After cold stratification, radicles emerged from about 50%...

In Japan the black locust (Robinia pseudoacacia L.) is undergoing rapid habitat expansion, which has an adverse effect on native vegetation. It is therefore a priority to clarify the regeneration characteristics of the black locust and establish adequate management of this invasive species in Japan. To determine the germination characteristics of p...

Understanding the potential for ornamental plant species to become naturalized in a nonnative habitat requires information on seed germination in order to help predict responses of the species to the natural environmental conditions of its new habitat. Cardiocrinum giganteum var. giganteum, which is native to the Himalayas, has been introduced as a...

Temperate forests are disjunct in the Northern Hemisphere, having become fragmented from the earlier widespread (Tertiary) boreotropical forest. We asked 'What are the contemporary patterns of population variation in ecological traits of a Tertiary relict in a macroecological context?'. This issue underpins our understanding of variation in populat...

Hard seeds of some legume species can germinate after seed-feeding insects bore through the seed coat and consequently break seed dormancy. Larvae of bruchine beetles are the main seed feeders attacking many legume species. Boring of the hard seed coat by bruchine beetle larvae enhances the germination percentage of legume species, but consuming to...

In Japan, the herbaceous perennial Corydalis ambigua Cham. et Schlecht. occurs in Tohoku and Hokkaido, where it grows in deciduous woodlands. Seeds have an underdeveloped embryo that is physiologically dormant at the time of dispersal in late May. In laboratory experiments, embryos did not grow when kept continuously at 5 °C or at alternating diurn...

Seeds of some temperate plants require multiple treatments to break complex forms of dormancy, such as deep simple double morphophysiological dormancy (MPD), but embryo growth and radicle and cotyledon emergence have not been studied in depth for this level of MPD. Here we studied Trillium camschatcense, a species that is purported to have this MPD...

Many tiny yellow poppies are grown in the town area of Rishiri Island, Japan. Because the phenotype of this cultivated poppy is similar to that of Papaver fauriei, which is endemic to Mt. Rishiri, Rishiri Island, residents on the island call the cultivated poppy “P. fauriei” although the origin of the cultivated poppy is uncertain. To estimate the...

Only a few studies have considered the possibility that low temperature requirements may vary among stages of dormancy break in seeds with morphophysiological dormancy (MPD). We show that this lack of consideration in previous studies on seed dormancy and germination of Aegopodium podagraria might explain the low germination percentages and/or the...

To better understand the germination ecophysiology of the genus Lonicera, the dormancy class, temperature requirements for embryo growth and radicle emergence and phenology of seedling emergence were determined for Lonicera caerulea var. emphyllocalyx. At maturity, seeds have an underdeveloped embryo (approximately 28% of the length of full-grown e...

A sub-global assessment (SGA) began in Japan in November 2006, and is projected to end in May 2010, when the Tenth Conference of the Parties to the Convention on Biological Diversity (COP10) will be held in Nagoya City. Since May 2008, we have been involved in the evaluation of the Hokkaido Cluster, one of four clusters assessed. This report provid...

In this study, we conducted experiments to accumulate practical information on the propagation and establishment of a population of Cardiocrinum cordatum var. glehnii by seed sowing. C. cordatum var. glehnii seeds require approximately 19months from seed dispersal to cotyledon emergence in the field. However, the period from seed dispersal to radic...

In an investigation of seed germination in Cardiocrinum cordatum var. glehnii, embryos in fresh seeds in October were underdeveloped and did not grow until September of the following year. Then, they grew rapidly and had fully elongated by early November. In the second spring after dispersal, radicles emerged under snow in late March and after snow...

Adonis ramosa (Ranunculaceae) is a plant whose risk of extinction is increasing in Japan. In this study, we show that there is a significant possibility of establishing an A. ramosa population by sowing seeds or transplanting plants in a seminatural broad-leaved deciduous forest floor. Immediately after seed collection in early June, seeds were sow...

To create a populationof Gageα t．utea Ker−Gawl ．by sowing or planting container grown individuals， the effects f storage methods ，sowing time，burialdepth，and lighton seeds were investigated．The stage of germination was distinguished between radicle emergence from the seed coat and cotyledon emergence above ground．Seeds stored in dry conditions at 5...

To clarify the effects of sheep pasturing to meadow in open space on plant height, standing crop, and people's impression, six sheep were pastured in the grass (about 800m&sup2) in the campus of Hokkaido University for 13 days. Although the plant height or standing crop could be controlled by sheep grazing, the extent differed depending on the plan...

The effects of temperature on embryo growth, radicle emergence and cotyledon emergence of Gagea lutea (Liliaceae), a perennial herb widely distributed in Europe, eastern Siberia, the Kurile Islands, Sakhalin and the Far East, were monitored outdoors and in laboratory tests. In Japan, this species inhabits open secondary grasslands and deciduous for...

本州中部以北の海岸の砂地にみられ初夏に黄色の花を付けるマメ科のセンダイハギは, 時として大きな個体群を形成し，海岸地域の修景緑化材料として有望と思われる。本研究ではセンダイハギの種子発芽について知見を得た。種子は物理的休眠を有しており，その程度は採取場所や年によって異なったが，40-50分間の濃硫酸への浸漬によって種皮に亀裂や穴が生じて吸水が可能になり高い発芽率を示した。また，凍結処理や凍結, 解凍処理では種皮に微細な孔を生じたが発芽には至らなかった。休眠が打破された種子は，30°C付近で最も高い発芽率を示したが，20°C以下の低温では発芽率が低下した。また変温によっても発芽が促進された。4cm以上の埋土深では発芽しなかった。

Astragalus adsurgens is a rare species in Hokkaido, Japan. However, there are many large populations of A. adsurgens in Oshima-oshima Island in Hokkaido, and this advanced to bare ground. This suggests that this species is a promising vegetation recovery material around their habitat area, though it is a rare species in Hokkaido. In this study, to...

Erythronium japonicum (Liliaceae) (Japanese name, katakuri) is indigenous to Japan and adjacent Far East regions. We examined their embryo elongation, germination, and seedling emergence in relationship to the temperature. In incubators, seeds did not germinate at 20°/10° (light 12 h/dark 12 h alternating temperature), 20°, 15°, 5°, or 0°C with a 1...

During the development of polyembryony in Ophiopogon japonicus (L.f.) Ker-Gawl, no embryo was differentiated for the first two months after flowering. A meristematic structure appeared at the distal end of the embryo sac from the end of August to early September and developed into a globular embryo. New embryos appeared from within the embryo, whic...

海浜地域におけるハマヒルガオの景観形成素材としての利用および本種の保全を目的として, いくつかの休眠打破処理を試み, 硬実種子であることを確認した。そして硬実性解除のための適切な硫酸処理時間とその機作を明らかにした。ハマヒルガオの種子をシャーレに播種して恒温器内に置き, 発芽の過程を観察した。その結果ハマヒルガオの無処理種子は, 発芽時の温度や光条件そして採取場所, 採取時期, 貯蔵期間にかかわらず, 吸水して発芽できる種子は数%にとどまる硬実種子であった。しかし種皮への針による穿孔, 紙ヤスリによる傷付け, 濃硫酸への浸漬処理によって吸水し発芽が可能になった。それらの処理の中でも硫酸処理がもっとも効率的であった。濃硫酸処理の効果は, 種子採取の場所や時期によって異なったが, 60分から12...

硫酸処理によって硬実休眠が打破されたハマヒルガオ種子の, 発芽適温, 光の影響, 埋土の影響および貯蔵方法について, 室内で恒温器を用いた実験を行った。硫酸によって休眠が打破された種子は, 播種30日後には10～30℃の幅広い温度で80～95%の高い発芽率を示したが, 平均発芽日数は25～30℃で短くなり, 10℃では著しく長くなった。明・暗の光条件はこれらの発芽温度特性に影響を及ぼさなかった。砂の表面に置いた休眠打破種子は, 38%の発芽率にとどまった。これは種皮の表面からの蒸発によって十分な吸水が行われないためと考えられた。一方, 0.5～6cmの砂の中に埋土すると最終的に73～86%が発芽し, 埋土の深さが深くなるほど平均発芽日数は長くなった。また, 硫酸によって休眠を打破した種子は,...

アジュガの苗の繁殖効率を高めることを目的として, 葉挿しによる繁殖方法を検討した。はじめに恒温器内の実験で発根条件を明らかにした。発根適温は20～250℃であり, 発根のためには2500lx以上の照度が必要であった。葉の貯蔵を行う場合は0～5℃で貯蔵するのが適切で, その貯蔵限度は4週間であった。また, 1枚の葉からだけでなく, 上半葉, 下半葉からも発根した。次に屋外の実験において, 肥料を混入した用土を用いてビニールポットに直接葉挿しを行った。屋外での葉挿しの適期は6, 7月であり, 3ヶ月後には直径10cm程度の定植可能な大きさにまで生長した。ポット当たりに挿す葉の枚数を2枚にすることで, 1枚挿しに比べて育成中の枯死率を低下させることができ, 生長量も1.5～1.8倍程度に増加させる...

海浜植物の保全と海浜地域での景観への利用を目的としてハマエンドウの種子発芽特性を明らかにした。ハマエンドウの種子は硬実種子であることが確認された。濃硫酸に浸漬することで種皮に穴と亀裂を生じ, それによって硬実を打破できた。40分間硫酸処理された種子は10～20℃の温度範囲で90%以上の発芽率を得ることができた。しかし, 25, 30℃ では発芽率が低下し, 発芽速度は遅くなった。硫酸処理後の種子は, 乾燥3℃, 無乾燥3℃, 無乾燥室温のいずれの条件下で貯蔵しても, 少なくとも1年間は処理直後の発芽力を維持できた。また, 自生地の砂を覆土した実験では, 6cmの覆土でも25日目には80%の発芽を見た。

福井県地方を中心に, 畦畔の雑草を抑制し, 農村景観の美化を図ることを目的として, 強健で被覆速度が速く, 花の美しい地被植物が導入されている。本研究では, それら地被植物の中でも最も多く導入されているセイヨウジュウニヒトエ (Ajuga reptans L.) の被覆速度ならびに雑草抑制効果と除草時間を評価した。1994年10月11日に4, 9, 16, 25本/m2の植栽密度とポリエチレン製マルチ被覆の有無を組み合わせた実験区を設け, 1996年12月まで, 毎月被覆率・株高・開花数を測定し, 年に3回手取り除草時間と雑草量を測定した。植栽後まもなくは, 植栽密度が高いほど雑草量が多くなり, 除草時間も長くかかった。しかし, その後は植栽密度が高いほど被覆率は早く高まり, 植栽後10か月...

野生草花の緑地への導入に対する技術的手法を明らかにするために, ノコンギクを材料として種子の発芽特性と挿し木による増殖の可能性, そして群落を美しく維持するための刈取り時期について検討した。ノコンギクの種子は暗条件下でも15～25℃ でよく発芽し, 明条件下なら30℃ でも高い発芽率を示した。また, 25℃ 以下で乾燥貯蔵しておけば, 種子の発芽能力を1年間はほぼ保持できた。したがって, 播種後の水分が確保できるならば, 播種適期は広いと判断される。ただし春に播種するとその年の秋には開花させることができた。さらに適切に水管理された挿し木実験では, 発根促進剤を用いなくとも90%以上の発根率が得られ, 挿し木による増殖も容易であると思われる。群落を年1回7月初旬あるいは年2回6月初旬と8月初旬...

4種の野生草花の種子発芽について, 種子の貯蔵条件および発芽時の温度, 光条件を相互に組み合わせた実験を行った。 ヂシバリは光による発芽への影響は認められず, 3℃の低温湿潤貯蔵 (湿層処理) により, 発芽は抑制された。 ニガナは明条件または湿層処理によって発芽が促進され, 両条件が重なった時に著しく発芽率は高まった。 コウゾリナ, フランスギクは明条件または湿層処理を行うことで発芽率が高まり, 発芽適温の幅も広がった。