Investigation of change in tangential strain on the inner bark of the stem and root ofBetula platyphylla var.japonica andAcer mono during sap season

Although it is well known that sap exudation during early spring in temperate deciduous trees occurs in response to daytime warming and nighttime cooling, the mechanisms of the process are not yet fully understood. Previous theories suggested that changes in stress in the wood caused by daytime heating and nighttime cooling might be linked with sap flow. Consequently, a study of itaya-kaede maple (Aver mono) and shirakamba birch (Betula platyphylla var.japonica) looked at tangential strains. One-hour intervals for 3 years of the tangential strains on the inner bark of stem and root were measured in itaya-kaede maple and shirakamba birch during the sap exudation season. The measurements indicated different mechanisms of sap exudation in these two trees. During the sap exudation season in late March, when the temperature fluctuated around 0°C, the tangential strain in the root of itaya-kaede maple showed expansion in the daytime and contraction at night. Conversely, in early April the tangential strain in the root of shirakamba birch exhibited contraction in the daytime and expansion at night. The changes in tangential strains in itaya-kaede maple were attributed to conditioning, a known concept used to explain the uptake mechanism of soil water in maple and its exudation during early spring. However, because the change in tangential strain in the roots of shirakamba birch was similar to that found during the rampant season, sap exudation was not attributed to conditioning but to the plentiful supply of water from the roots. The implications of these mechanisms are that different sap harvesting techniques may be appropriate for different tree species.     

The spatial pattern of a northern conifer-hardwood landscape

A geographic information system, fractal analyses, and statistical methods were used to examine the spatial distributions of old growth hemlock, northern hardwood, mixed hardwood/hemlock stands and wetlands with respect to each other and also soils and topography. Greater than 80% of the stands of any covertype were less than 20 ha in area. Nearly pure hemlock and northern hardwood stands were associated with soils having a fragipan, while mixed hardwood/hemlock stands were associated with sandier soils. Hemlock stands were distributed independently of hardwood and mixed hardwood/hemlock stands, but hardwood and mixed hardwood/hemlock stands were usually surrounded by hemlock. Bogs and lakes were usually surrounded by hemlock stands and are distributed independently of hardwood stands. The shapes of all stands vary from extremely simple to extremely complex, with a general tendency for hemlock stands to be more convoluted than hardwoods. The analyses suggest segregation across soil types and a disturbance regime favoring the establishment of hardwoods and mixed hardwood/hemlock stands in a hemlock matrix as reasons for the origin of the observed spatial patterns.     

PHOSPHORUS NUTRITION AND MYCORRHIZAL GROWTH RESPONSE OF BROADLEAF AND NARROWLEAF BIRDSFOOT TREFOILS

In Argentina narrowleaf trefoil (Lotus glaber) predominates over broadleaf trefoil (Lotus corniculatus). Researchers have suggested this predominance occurs because L. glaber grows better at low levels of P availability. I studied the effect of increasing phosphorus (P) nutrition and mycorrhizal growth response of Lotus corniculatus and Lotus glaber in a soil of low available P. L. corniculatus was more efficient in P utilization than L. glaber and produced larger yields of shoot tissue per unit of P. The critical P concentration, measured as a percentage of P in the shoot required to achieve 90% of maximum shoot yield, was 0.22 in L. corniculatus and 0.28 in L. glaber. The roots of both two species were heavily infected by arbuscular micorrhizae (AM), and both mycorrhizal and nonmycorrhizal plants responded strongly to added P in soil. This suggests that both species are at no advantage or disadvantage whether mycorrhizal or nonmicorrhizal. The fraction of roots colonized by AM fungi differed between species at low levels of added P but was similar at high levels of added P. The specific root length (cm g^?1) of mycorrhizal plants was greatest in L. corniculatus when P was insufficient to achieve maximum growth. The lower critical P concentration and the higher specific root length at low levels of P nutrition may be why L. corniculatus is superior to L. glaber in soils low in P. Therefore, the predominance of L. glaber compared with L. corniculatus in Argentinean soils is not due to ability of L. glaber to grow better in soil at low levels of P availability.     

银白槭育苗技术研究

银白槭具有很高的观赏价值,值得在国内推广应用。对美国进口的干燥种子和鲜活种子进行播种育苗试验,并对银白槭的出苗率、当年生长量与育苗技术进行研究。试验结果表明,苗床直播与穴盘点播,鲜活种子具有萌芽早、出苗快、出苗率高的特点。穴盘点播的鲜活种子的出苗率为84.0%,发芽持续时间为13d。银白槭春播种子当年平均高生长量为121.30cm,夏播种子当年平均高生长量为80.5cm。银白槭生长季需加强水肥管理,促其健壮生长,及时喷施农药预防天牛及红蜘蛛等。幼苗冬季最好假植以保护越冬。     

诱导子对茶条槭悬浮细胞核酸酶的激活研究

为揭示真菌诱导子诱导茶条槭悬浮细胞发生凋亡的原因,以茶条槭悬浮细胞为材料,采用细胞形态观察、基因组DNA电泳分析以及核酸酶活性检测等手段,研究了真菌诱导子对细胞发生凋亡的影响。结果表明真菌诱导子处理的细胞,其形态结构发生变化,DNA降解成呈梯状的条带,且检测到分子量大约为50、40、41、38、34 kD的核酸酶。通过这些结果说明,茶条槭悬浮细胞在真菌诱导子诱导下发生细胞凋亡,并伴有特异核酸酶被激活。     

Seasonal biology and management of the maple shoot borer, Proteoteras aesculana (Lepidoptera: Tortricidae), in production nurseries

BACKGROUND: Proteoteras aesculana (Riley), a caterpillar that causes tip dieback and kills the central leader of maples, is an important nursery pest. The authors sought to develop a pheromone lure, use it to clarify the pest's seasonal biology, determine when and where infestations originate and extend the management window.RESULTS: Gas chromatography, electroantennographic detection and trapping showed that (Z)-dodec-8-en-1-ol (Z8-12:OH) is the major sex pheromone component. Flight began in March, peaking in early spring. Larvae developed during April and May, giving rise to moths active in late May and June. No additional larvae were found in maples following that flight. Sporadic moth captures occurred into November, suggesting that adults overwinter. Three parasitoid species, all new host records, were documented. A different tortricid, Episimus tyrius Heinrich, caused leaf-tying damage in late summer. Maples shipped from Oregon were free of shoot borers, refuting speculation that larvae overwinter in buds. One bifenthrin spray applied from just before bud break at onset of moth flight to just after peak flight when shoots had two pairs of leaves reduced infestation by 96-100%.CONCLUSION: Maples are infested soon after planting in Kentucky nurseries via eggs laid in early spring. The temporal window for preventive control is broader than previously thought. Copyright (c) 2008 Society of Chemical Industry.     

茶条槭化学成分及药食应用研究进展

综述了国内外近30年来关于茶条槭化学成分、药理作用和药食应用等方面的研究进展,并对茶条槭的进一步开发利用进行了展望。     

元宝枫叶片花色素苷的提取及其稳定性研究

元宝枫（Acer truncatum Bunge）又名华北五角枫、平基槭,属于槭树科(Aceraceae)槭属（Acer.L）。元宝枫叶形秀丽,嫩叶红色,秋叶黄色,红色或紫红色,为优良的秋色叶树种,宜作庭荫树、行道树或风景林树种,元宝枫树冠荫浓,树姿优美,是北方重要的秋色叶树种。 花色素苷(anthocyanin)是一种类黄酮物质,存在于大部分的花和果实及一些植物的茎和叶中,对植物的蓝、紫、红、橙等色泽起主要贡献。虽然元宝枫做为常用红叶绿化树种被广泛应用,但由于元宝枫存在秋季变色株系差异较大,周边环境等因子对元宝枫叶片变色程度产生不同影响;因此通过对元宝枫秋季叶片花色素苷的提取及稳定性的研究,对探索元宝枫秋季叶片变色机理和优良无性系选育,丰富完善园林造景资源具有重要意义。     

引种紫花槭叶属性的年际变化

采用叶色量化结合主要生理指标测定和生物学观测等方法,研究了哈尔滨地区引种的园林绿化秋季色叶树种紫花槭的叶属性年际变化。结果表明,在驯化过程中,紫花槭的叶属性在年份间存在显著差异,从一定程度上反映了引种紫花槭的适应性呈逐年提高趋势。     

茶条槭的生物学特性与培育技术研究

茶条槭为是中国自然分布的乡土槭树之一。通过在江苏南京的育苗试验,阐明了其幼苗生长特性,并概括了壮苗培育技术,以期为该种植物的合理利用提供参考。