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Four new compounds, phomadecalin F (1), 8α-monoacetoxyphomadecalin D (2), 3-epi-phomadecalin D (3), and 13-hydroxylmacrophorin A (4), were isolated from the endophyte, Microdiplodia sp. TT-12 together with two known compounds, phomadecalins C (5) and D (6). The structures of the compounds were elucidated by NMR spectroscopic and mass spectrometric analyses in combination with chemical means. The antibacterial activities of the isolated compounds were evaluated. Compound 4 was weakly active against Raffaelea quercivora.

We examined the effect of early and intense pruning on light intensity under the canopy, individual growth, diameter–height relationships, and epicormic shoot dynamics in young hybrid larch (Larix gmelinii var. japonica × L. kaempferi) to establish a new effective management method for hybrid larch plantations. The objective is to produce high-quality wood while reducing silviculture costs using a combination of low-density planting and early and intense pruning. In a young hybrid larch plantation, we pruned branches to two different heights (2 and 4 m above ground level) using a no-pruning treatment as a control. Although the growth rates were lower in the heavy pruning treatment (4 m above the ground level) than in other treatments in the year following pruning, when measured 4 years later, growth did not differ between treatments. The number of epicormic shoots increased in the year following pruning, as did the relative photosynthetic photon flux density (rPPFD). The number of epicormic shoots was also dependent on the size of individual trees. However, survival of epicormic shoots was not sufficiently high to be problematic for high-quality timber production. If branches are pruned carefully such that the rPPFD does not rise above 20%, the emergence of epicormic shoots can also be controlled. Our results indicate that early and intense pruning is an effective component of a new management system for hybrid larch plantations.

Norcolensoic acid (1) was isolated from both the fruiting bodies and the liquid culture of Lachnum virgineum. The structures of 1 was determined using spectroscopic methods. Compound 1 was isolated for the first time from this fungus. Compound 1 showed moderate antibacterial and phytotoxic activities.

ブナ種子の長期貯蔵条件を見出すため, ヨーロッパブナにおいて提唱された貯蔵条件が日本のブナにも適用できるかどうか検証した。種子の含水率を3段階 (弱乾燥, 11.3%; 中乾燥, 6.1%; 強乾燥, 4.0%) に調製して−20oCで冷凍保存したところ, 弱乾燥処理は貯蔵4年目に発芽率が大きく低下し, 6年目に発芽能力を失った。強乾燥処理は貯蔵4年間で発芽率の低下はみられなかった。中乾燥処理で貯蔵5年まで高発芽率 (60%) が維持され, 貯蔵10年後にも発芽率は25%を示した。中乾燥処理の結果は追試験 (含水率6.6%, −20oC) によっても支持され (貯蔵7年で発芽率60%程度を維持), 長期貯蔵のための最適含水率は6∼9%と考えられた。貯蔵8年間で種子含水率の増加は1%に留まった。貯蔵4年目から本葉展開に至った実生の8∼25%に形態異常がみられたが, その後苗畑での生育には支障なかった。今後は, 北海道で確認された貯蔵条件が国内の他地域でも適用できるかどうか検討する必要がある。

To examine the proximate factors causing mast seeding in Fagus crenata Blume in Hokkaido, northern Japan, we analyzed a 13-year time series of seed production in relation to both previous reproduction and weather conditions. In an autocorrelation analysis we observed a significant negative correlation in 1-year time lags for the log-transformed total seed crop. This indicates that internal resource dynamics are important for mast seeding. A strong negative correlation was observed between the total seed crop and minimum temperature from late April to mid-May in the year preceding flowering. The critical minimum temperature from late April to mid-May for total seed crop at all five sites was about 1.0 °C higher than the 22-year (1979–2000) mean of the minimum temperatures, above which very few seeds were produced. These results show that a weather cue triggers the cessation of reproduction in F. crenata. Regression models that included reproduction in the previous year and minimum temperature explained 57.8%–83.1% of the total seed crop at the five study sites. Therefore, resource dynamics and weather cues are clearly involved in mast seeding in F. crenata.

Summary 1 Two non-mutually exclusive hypotheses have been proposed to explain the evolutionary advantages of mast seeding (the intermittent production of large crops of flowers or seeds by a population of perennial plants). Mast seeding could have evolved as a result of increased pollination efficiency in mast-flowering years and/or as an anti-predator adaptation that increases the survival of seeds by alternately starving seed predators in non-mast years and satiating them in mast years. 2 We investigated annual seed crops to test the relative contributions of pollination efficiency and pre-dispersal predator satiation to mast seeding in Fagus crenata, a tall tree species dominating cool-temperate forests in Japan. Thirteen-year (1990–2002) time series data were collected for five beech forests in south-western Hokkaido. 3 The negative relationship observed between the pollination failure rate and the total seed crop in the current year supports the pollination efficiency hypothesis. The predator satiation hypothesis was also supported by the fact that the predation rate showed a good fit to the ratio of successive total seed crops, suggesting that a numerical response (starving the predator in low seed years) operated in F. crenata. 4 Key-factor analysis revealed that pre-dispersal seed predation had a larger effect on seed production per flower than did pollination efficiency. 5 We used a simulation model to examine how the magnitude of fluctuation in the total seed crop would influence the pollination failure rate, the predation rate and the viable seed rate. The mean levels of fluctuation of total seed crops of F. crenata were just large enough to provide maximum benefits from predator satiation at some sites. 6 Mast seeding in F. crenata thus appears to be determined by selective pressures from its seed predators.

Three polyacetylene compounds, 1, 2 and 3, have been isolated from the organic extract of a liquid culture of Hypsizygus marmoreus (Peck.) Bigelow (Japanese name: Bunashimeji). The structures of 1, 2 and 3 were determined by using spectroscopic methods. Compound 3 is new, and was identified as 8(E)-decene-4,6-diyn-1,2,10-triol. Compound 1 exhibits antifungal activity against the pathogenic fungus Raffaelea quercivora responsible for Japanese oak wilt

Scaling of water absorption and water loss by seeds on various soil surfaces was simulated using seed analogues constructed with paper pulp. Three sizes of analogue seeds (large, medium and small) were laid on three types of soil surface (coarse, medium and fine texture). To estimate the amount of water absorbed by a seed during a fixed time interval, the difference in seed weight from the start of the experiment was used. The scaling of water absorption necessary for germination was also studied using actual seeds of 14 species representing a range of seed sizes. Scaling coefficients between the amount of absorbed water by an analogue seed (net water gain) and seed mass were usually lower than 1: small seeds absorbed water more rapidly than large ones. The water loss of analogue seeds was also correlated with seed mass with a scaling coefficient lower than 1, but the amount of water loss itself was far smaller than the absorption. On the other hand, the germination of actual seeds revealed that the amount of water necessary to start germination was proportional to seed mass. Thus, smaller seeds have an advantage over larger seeds in more rapidly attaining the water content necessary for germination. Moreover, small seeds can penetrate through small cracks in the soil surface and thus enjoy a double advantage in a microsite that promotes water absorption and minimizes desiccation.

Geographic variation in seed size of Japanese beech (Fagus crenata Blume) was examined. Seed size was not significantly correlated with climatic factors, such as mean annual temperature, warmth ind...

Japanese oak wilt (JOW) is a tree disease caused by the fungus Raffaelea quercivora, which is vectored by the ambrosia beetle, Platypus quercivorus. In a screening study of the inhibitory active compounds from fungi, a new cytosporone analogue, compound 1, was isolated from the endophytic fungus Cytospora sp. TT-10 isolated from Japanese oak, together with the known compounds, integracin A (2), cytosporones N (3) and A (4). Their structures were determined by extensive 1D– and 2D–NMR spectroscopic and mass spectral analyses. Compound 1 was identified as 4,5-dihydroxy-3-heptylphthalide and named cytosporone E. Compounds 2 and 3 showed antimicrobial activity against Raffaelea quercivora.