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In order to prevent the spread of COVID-19, various online collaborative learning environments have been recently designed for project-based learning (PBL) programs and lectures, which are compulsory subjects for more than 500 students. For the PBL programs, 45 groups of 500 students were formed, and an online collaborative learning environment was established with 16 faculty members providing guidance. For the lectures, an online flipped classroom environment was established with 600 students divided into four classrooms, and online peer teaching was realized by about 140 student groups. This paper describes a large-scale PBL learning program with flipped classes built online to encourage the active and autonomous learning of students and ensure education quality during the pandemic.

Limonium sinuatum (L.) Mill. (2n = 2x = 16) is a popular ornamental plant with dimorphism of pollen grains (type A and type B) and stigmas (papilla and cob-like). We applied polyploidy breeding to this species in order to introduce desirable traits. Tetraploid and mixoploid L. sinuatum plants were successfully obtained with oryzalin treatment of L. sinuatum ‘Early Blue’ seeds. All three tetraploids had increased leaf width, stomatal size, flower length, and pollen width compared to those of the diploid, and tetraploids had four germinal pores of pollen grains, whereas the diploid had three. All tetraploids had type A pollen grains and cob-like stigmas. Furthermore, the growth of cultivated tetraploid plants was slow, with later bolting and flowering times. Mixoploids Mixo-1 and Mixo-3 were estimated to be polyploidy periclinal chimeric plants consisting of a tetraploid L1 layer and diploid L2 layer, and Mixo-2 was estimated to be a polyploidy periclinal chimeric plant consisting of the diploid L1 layer and tetraploid L2 layer. Mixo-4 had tetraploid L1 and L2 layers. Mixoploids, except Mixo-4, had type A pollen grains and cob-like stigmas, whereas Mixo-4 had type B pollen grains and papilla stigmas. These polyploids will be useful as polyploidy breeding materials.

A survey of the insects visiting common buckwheat flowers and examination of the pollen attached to the insects captured at the field in Hokkaido was carried out in order to determine their role as pollinator. Two bumblebee species, Bombus ardens sakagamii and B. hypocrite sapporoensis, were captured as the predominant species (75.4%) and 97.6% of B. ardens sakagamii and 96.0% of B. hypocrite sapporoensis had tetraploid common buckwheat pollen attached to their body surface even though they were captured in a diploid common buckwheat field. From these results, these two bumblebee species were thought to be the main pollinators of common buckwheat in Hokkaido for the first time.

イチゴ‘ベルルージュ’の茎頂培養由来の幼植物の生長におよぼすランナー採取日の影響を検討した.その結果, 幼植物の生長はランナー採取期間によって異なり, ランナー発生期の前期 (6月23日～8月4日) と後期 (8月18日～9月21日) に大別できた. 後期の幼植物は前期に比較し, 展開葉数が少なく, 草丈は高くなる傾向を示した. また, アベナテストにより母株茎頂付近のオーキシン活性を調べたところ, 初回採取日をピークに活性が低下していくことが明らかになった. これらの結果から, 茎頂培養ではランナー発生前期の材料を用いる方がより適していることが明らかになった.

Petasites japonicus v. giganteus (Japanese butterbur) and Polygonum cuspidatum (Japanese knotweed) exude a large quantity of guttation fluid from the leaf edge. The concentrations of Ni and Mn in the guttation fluid from Petasites japonicus v. giganteus grown on ultramafic soil were 2.24 (Ni) and 0.32 (Mn) mg L−1, respectively, on the average, whereas those in the guttation fluid from Polygonum cuspidatum were 0.22 (Ni) and 3.13 (Mn) mg −1, respectively. The Ni concentration in the leaves of Petasites japonicus v. giganteus was about 5 times as high as that of Polygonum cuspidatum, especially at the leaf edges, and the Mn concentration in the leaves of Polygonum cuspidatum was about 6 times as high as that of Petasites japonicus v. giganteus. Thus, the concentrations of Ni and Mn in both the guttation fluid and leaves of Petasites japonicus v. giganteus were opposite to those of Polygonum cuspidatum. The contents of K, Mg, and Ca in the guttation fluid from Petasites japonicus v. giganteus were h...

イチゴにおける茎頂培養の作業を分散するため, ランナーの低温貯蔵が茎頂の生長に与える影響について調査した. その結果, 休眠が深い品種‘ベルルージュ’では11日程度の低温貯蔵 (4℃) で生存率の低下は認められず, 展開葉数が増加した. また,‘宝交早生’などの休眠が中程度および深い品種群でも同様の傾向が見られた. 一方,‘とよのか’などの休眠が浅い品種群の生育は低下する傾向を示した.このように, 低温貯蔵が茎頂の生長に与える影響は品種によって異なるが, 休眠が中程度および深い品種における茎頂の生長はランナーの低温貯蔵によって悪影響を受けず, 低温貯蔵が利用できる可能性が示唆された.