Leaf Area Calculation Model of E.urophylla and E.grandis×E.urophylla

[Objective] The aim was to build an optimal leaf area measurement model of E. urophylla and E. grandis×E.urophylla. [Method] The correlation between leaf area and leaf＇s eigenvalue of E. urophylla and E. grandis×E.urophylla were studied. [Result] There was certain difference in leaf characteristics values between the 2 species. The leaf areas of E. urophylla and E. grandis×E.urophylla both had significant correlation with leaf length,leaf width,leaf perimeter,leaf length × leaf width,the ratio of leaf length to leaf width,shape factor,etc.,so the factors could be constructed into a regression model with leaf area. Among them,the best 2 models for leaf area calculation which were built by leaf length × leaf width of E. urophylla and E. grandis×E.urophylla both had relatively high accuracy and practical applications. [Conclusion] The research provides a simple and effective leaf area measurement method for studies on the 2 tree species.

Soil microorganisms alleviate the allelopathic effect of Eucalyptus grandis × E. urophylla leachates on Brassica chinensis

Soil microbes may be critical players in determining the allelopathic potential of some plants. Low levels of plant community biodiversity in Eucalyptus plantations have been attributed to the allelopathic potential of these tree species. The role of soil microbes in the allelopathic effect of leaf leachates of the hybrid tree Eucalyptus grandis x E. urophylla, was tested in Petri dish assays with Brassica chinensis as a receiver plant. Soils were collected from either a local garden (soil A) or a Eucalyptus plantation (soil B) and half of each soil was sterilized to remove microbes. These soils were then treated with E. grandis x E. urophylla leachates for 0-72 h. Seed germination of B. chinensis was significantly inhibited in soils treated with leaf leachates relative to untreated soils. The inhibitory effect of the leaf leachates was more pronounced in sterilized soils. Total phenolic content was obvious lower in nonsterile leachate-treated soils than in sterile soils. Biomass of B. chinensis was negatively correlated with the total phenolic content in soils. Our findings suggest that soil microbes can alleviate the allelopathic potential of Eucalyptus and thereby its negative impact on plant growth.

Comparative microsporogenesis and flower development in Eucalyptus urophylla×E.grandis

Microsporogenesis and flower development in Eucalyptus urophylla × E. grandis were examined using chromosome tableting to provide a method to predict the meiotic stages in this species. Although microsporogenesis was normal, cytokinesis during meiosis of pollen mother cells occurred simultaneously, with strong asynchronism observed in the two different lengths of stamens in a flower bud. In a single flower, the developmental period of microsporogenesis in anthers on the longer stamens was always ahead of those on the shorter stamens. Flower development was also asynchronous at different locations on a branch. Flower buds on the upper side of the branch were larger in diameter than those on the lower side. In addition, a correlation was observed between microsporogenesis development and flower bud diameter growth. The pachy- tene stage was first observed when the diameter of the flower buds increased to 3.0 mm, and the majority of the meiotic stages were observed when bud diameters ranged from 3.5 to 5.0 mm. This study showed that the developmental stages of microsporogenesis in Eucalyptus urophylla × E. grandis could be distinguished readily, which may be applicable to future breeding studies.

Purification of AS-CMP effluent by combined photosynthetic bacteria and coagulation treatment

The effluent from the pulping of E. urophylla by alkali sodium sulfite chemi mechanical process(AS-CMP) was characterized for its biodegradability by photosynthetic bacteria (PSB). Chemical coagulation post treatment of biotreated wastewater was also studied. One month continuous treatment in the laboratory indicated that the COD Cr , BOD 5 and SS removals in biotreatment stages reached 56%, 83% and 89% respectively, and the CH 2Cl 2 extractives decreased from 10.7 mg/L to 7.7 mg/L. In chemical coagulation post treatment stage, the effects of process conditions, such as coagulant dosage, pH value and the coordinated coagulation flocculation treatment of three kinds of coagulants on coagulation effectiveness were discussed. The optimum operating conditions were given.

Monoterpene hydrocarbons,major components of the dried leaves essential oils of five species of the genus Eucalyptus from Cote d’Ivoire

The chemical composition of the essential oils obtained from the dried leaves of five species of the genus Eucalyptus (E. camaldulensis, E. de-glupta, E. grandis, E. torelliana, E. urophylla) growing in C?te d’Ivoire, was analyzed by means of GC and GC/MS. The density and the refractive index were measured. The major components of all these oils are: α-pinene, β-pinene, α-phellandrene, limonene, γ-terpinene, p-cymene and β-caryo-phyllene. The particularity of these oils is their monoterpene hydrocarbons major components.

Influence of Planting Spacing on Mechanical Properties of Eucalyptus grandis × E. urophylla Planted in China

The objective of this study was to understand influence of planting spacing on mechanical properties of Eucalyptus grandis × E. urophylla planted as a potential species for solid wood products in China. Four trees at age of 13 were selected from each of 6 groups of planting spacing and a total of 24 sampling trees were selected from the Dongmen Forestry Center of Guangxi Province in China. Furthermore, a one-meter-long log from each tree was cut into small blocks for wood properties testing. MOE, MOR and compression strength parallel to wood grain were determined in accordance with Chinese standards. In addition, wood density and shrinkage properties were measured. Statistical analysis by SAS software indicated significant differences among the 6 groups of planting spacings on the air-dried density, radial shrinkage and bending MOR properties at the 0.05 level, and also on the compression strength at the 0.10 level. However, it was observed that there is no significant differences among shrinkages in tangential and volume, and MOE.

Study on Machining Properties of Eucalyptus urophylla×E. grandis:I. Planing and Sanding Properties

The research method in this paper is based on the standard of American Society for Testing andMaterials (ASTM). Planing and sanding are selected to study the machining properties of E. urophylla × E.grandis plantation wood. Moreover, the reasons for machining defects are analyzed. The results show E.urophylla × E. grandis planted in south China is a good species with a great potential for solid woodutilization.

Growth Process of Eucalyptus urophylla × E.grandis Stand Based on Logistic Equation

Eucalyptus is the most valuable cultivated forest genus in the tropical and subtropical areas nowadays. It has been a challenge for foresters to model growth due to the genetic variations, management regimes, and multiple products generated from the plantations. In this paper, Logistic equation was used to study the stock growth process of E. urophylla × E. grandis plantation at age of 14 with 6 spacing treatments. And the biological interpretation of the parameters of Logistic equation was analyzed. The results show that it is flexible, precise and accurate to fit the growth process.

Study on Machining Properties of Eucalyptus urophylla× E.grandis:Ⅱ.Shaping,Boring,Mortising and Turning

The research method of this paper is based on the standards of American Society for Testing and Materials (ASTM). Four items that contain boring, mortising, shaping and turning are selected to study the machining properties of E. urophylla × E. grandis plantation wood. The reasons for machining defects are analyzed. The resultshows thatE. urophylla × E. grandis planted in South China isa good specieswith great potential for solid wood utilization.

Effect of Initial Moisture Content on Solar Drying Ratefor Eucalyptus grandis × E. urophylla

Wood drying is one of the most important process links in wood products processing.However, the existing drying methods mainly depend on heat to desiccate wood, which makes wooddrying consume roughly 40% - 70% of the total energy in the entire wood process. Using solar energyfor drying is greatly significant in two aspects of energy conservation and environment protection. Themoisture content (MC) of lumber affects not only the target value of wood drying, but also the heattransfer properties, moisture rate of expansion, etc., affecting dried lumber quality and drying rate.Eucalyptus grandis × E.urophylla lumbers were collected from Guangdong as test materials and dried inthe solar dryer with low temperature schedule and the effect of initial moisture content were primarystudied on drying rate. Experiments showed that solar drying was suitable for timber with high MC. Interms of drying rate and dried lumber quality, solar drying was as good as traditional steam drying withthe same schedule. And the solar dryer had distinct energy-saving effect.

短周期尾巨桉连栽林分生产力的研究

采用空间代替时间和定位观测相结合的方法对广西东门林场3．6年生尾巨桉林分生物量和生产力的连栽效应进行了研究。结果表明：林分平均单株生物量及林分生物量3代〉1代〉2代，不同代数尾巨桉器官生物量的大小顺序为干材〉干皮〉根蔸〉粗根〉光枝〉叶〉枯枝〉叶枝〉吸收根〉细根，地上与地下部分的比例分别为84．48％-84．75％和15．25％～15．52％；不同代数林分乔木层生产力为3代〉1代〉2代，连栽对尾巨桉林分生产力的影响有待进一步的研究。

不同林龄尾巨桉人工林生态系统生物量的研究

对闽南山区不同林龄(2、3、4、5、6年生)尾巨桉人工林生态系统的生物量进行了研究,其中林木生物量采用标准木法,林下植被和地被物生物量采用样方收获法。结果表明:乔木层生物量随着林龄的增加而逐渐增加,分别为45.14、69.22、92.20、111.82、175.09t/hm2,其中树干占的比例最大(44.5%～60.4%),细根最小(0.2%～0.6%);各林龄尾巨桉生产力依次为22.86、26.07、32.63、32.70、46.69t/(hm2·a),叶的生产力随林龄增长呈现先增加后减少的趋势;林下植被生物量依次为5308.83、7201.62、5676.47、4033.42、9183.13kg/hm2,其中灌木生物量在3年生时最大,为2121.89kg/hm2,而草本生物量在6年生时最大,达到1062.19kg/hm2;不同年龄尾巨桉地被物现存量大小表现为6年生>3年生>5年生>2年生>4年生,2～5年生时未分解层现存量小于分解层,6年生时则是分解层现存量小于未分解层。

不同林龄尾巨桉人工林土壤养分与微生物的耦合关系

基于对广西东南部不同林龄尾巨桉人工林下土壤养分和微生物测定及典范对应分析,探讨了不同林龄尾巨桉林土壤养分、微生物特征及其相互关系。结果表明:(1)不同林龄尾巨桉人工林下土壤有效磷和pH值的林龄效应不显著,土壤有机质、全氮、全钾、碱解氮随林龄增加基本上呈先增后减趋势,但各养分含量最高点的林龄有所不同。(2)土壤微生物种群总数、细菌、真菌及放线菌数量含量的林龄效应明显,土壤微生物种群总数量、细菌、真菌均在3a和8a龄林地含量较高,而且微生物种群中细菌比例最大,放线菌次之,真菌最小;细菌、真菌数量变化趋势相似,随林龄增长表现为增长减少再增长的趋势,放线菌数量变化没有一定规律。(3)微生物量碳(Cmic)、氮(Nmic)、磷(Pmic)的林龄效应均比较明显,Cmic从1a～8a龄林地呈折线变化,最高峰位于8a龄林地,1a龄林地次之;Nmic的变化趋势呈"V"状,1a和8a龄林地含量基本相同,最低点出现在3a龄林地;Pmic含量变化情况则相反,最高点位于5a龄林地,1a、8a龄林地含量较低。(4)典范对应分析表明,5个不同林龄尾巨桉人工林地土壤主要养分与微生物大部分不呈正相关或相关性不显著,说明影响土壤养分、微生物及其之间的关系不仅受林龄的影响,地形等其他因素也起到很大作用。

巨尾桉挥发油对真菌和昆虫的化感作用

对巨尾桉挥发油对真菌和昆虫的化感潜力及其化学成分进行了研究。结果表明,巨尾桉油乳液对真菌和昆虫均有抑制作用。随着巨尾桉油乳液浓度的增大,其对病原真菌(真菌粉蕉枯萎病菌、水稻稻瘟菌、香蕉胶胞炭疽菌和胡椒疫霉病菌)和有害昆虫(斜纹夜蛾和棉铃虫)的取食和化蛹的抑制作用明显增强。用GC/MS联用方法,对巨尾桉挥发油进行鉴定,相对百分含量在3%以上的化合物有:α-蒎烯(13·63%)、别罗勒烯(43·22%)、γ-萜品烯(5·49%)、(E)-3,7-二甲基-2,6-辛二烯醇(3·58%)、β-小茴香醇(4·58%)和2-氨基-3,5-二氰基-6-(4-甲氧基苯氧基)-吡啶(3·67%)。萜烯类化合物在巨尾桉挥发油对真菌和昆虫的抑制活性中起主要作用,巨尾桉人工林生物多样性较低可能与其化感活性有关。

不同林龄尾巨桉人工林凋落物和土壤C、N、P化学计量特征

为正确认识桉树(Eucalyptus spp.)人工林凋落物和土壤C、N、P时空分配格局及两者间的关系,对5个林龄尾巨桉林分凋落物及土壤C、N、P含量及化学计量比进行测定分析。结果表明,凋落物的C含量均显著大于土壤,且不同林龄间凋落物C含量无显著差异,1年生人工林土壤表层(0~20 cm)的C含量显著小于3~7年生,其他土层C含量在不同林龄间差异不显著。凋落物的N含量均显著高于土壤,且1年生人工林显著大于其他林龄的,而土壤表层的N含量以7年生人工林最大,1年生的最小。凋落物的P含量除1年生人工林显著大于3年生外,其他林龄间均无显著差异,土壤的P含量在不同林龄间的差异均不显著。凋落物C∶N随林龄呈逐渐增大趋势,且显著大于土壤层。凋落物的C∶P和N∶P在不同林龄间的差异不显著,但均显著大于土壤层。凋落物的N含量与表层土壤的C、N含量呈极显著负相关,凋落物的C∶N与表层土壤的C∶P,N∶P呈显著正相关,表层土壤C、N积累受到凋落物N的制约。因此,在桉树人工林经营管理过程中如何降低凋落物分解的N限制性、提高养分传递效率及合理施肥显得十分重要。

TDZ对巨尾桉(GL9)胚性愈伤组织诱导和再生的影响

The embryogenic callus induction and shoot regeneration were studied systematically in elite clone GL9 of Eucalyptus cultivated widely in south China.We investigated TDZ 0.02-0.05 mg·L-1 was the proper concentration.The callus induction rate was 92.9%—100%.When TDZ concentration was higher than 0.1 mg·L-1,the axillary bud germination was completely inhibited.TDZ 0.02 mg·L-1 with combinations of CoCl2 0.125 mg·L-1 could induct the embryogenic callus.The direct regeneration rate was 13.39%±1.03%,and with combinations of NAA 0.1mg·L-1 could not differentiate directly from callus,but higher regeneration rate(20.2%±13.3%) could be obtained by transferring callus onto regeneration medium.The size of callus can increase to 1.4 fold of its original size in the first subculture in modified MS+TDZ 0.02 mg·L-1 +NAA 0.1 mg·L-1medium and the average number of deep-pink-coloured masses of embryogenic cells on each callus was 8.4.In the second and third subculture,callus stopped growing further and the number of masses of embryogenic cells decreased gradually.Regeneration system could lay a good foundation for further transformation research.

巨尾桉单宁的提取分离及其抗菌抗氧化性能

采用超声波辅助法提取了巨尾桉叶中的单宁,大孔树脂吸附法纯化了粗提物,考察了提取物对8种常见菌种的抑制作用和对H2O2、DPPH.和.OH的清除作用。结果表明,巨尾桉单宁的提取得率为4.01%;经树脂分离纯化后单宁质量分数达到53.12%;巨尾桉单宁对除大肠杆菌外的供试菌种均有较强的抑制作用,纯化后的单宁对金黄色葡萄球菌、酵母菌和痢疾杆菌的最低抑菌质量浓度(MIC)均为1.0 g/L,对蜡状芽孢杆菌和沙门氏菌的抑制作用优于阳性对照物;粗提物、纯化物在质量浓度为0.50 g/L时对H2O2有最大清除率,分别为80.00%、89.12%,其IC50分别为0.11、0.12 g/L;抗坏血酸、粗提物和纯化物均在质量浓度为1.50 g/L时对DPPH.有最大清除率,分别为98.43%、88.97%和92.21%。在清除.OH体系中,粗提物、纯化物均在质量浓度为4.00 g/L时有最大清除率,分别为87.52%和94.32%,各试样对.OH的清除能力依次为抗坏血酸>纯化物>粗提物。

尾巨桉S2层微纤丝角及组织比量的径向变异

对8个尾巨桉家系木材的S2层微纤丝角和组织比量进行了系统研究.结果表明:(1)S2层微纤丝角自髓心向外呈缓慢的减小趋势.(2)导管组织比量径向上呈递增趋势,随后在第5至第11生长轮间略有降低或基本保持平稳;纤维组织比量从髓心向外的数个生长轮内变异规律不明显,近树皮处有上升或下降的现象;木射线组织比量随树龄的增加而减小,以后又呈波动性的增加或基本保持稳定;轴向薄壁组织比量径向上变动幅度较大,无一定规律.(3)家系间及家系内个体间的组织比量在个体水平上分布范围较广,呈正态分布,开展个体选择的潜力大.(4)S2层微纤丝角和纤维长度间存在一定负相关,但关系密切程度比针叶材低.

巨尾桉叶中皂苷的提取分离及其抗氧化活性研究

开展了从巨尾桉叶中提取皂苷的工艺优化研究。考察了温度、时间,溶剂用量对皂苷得率的影响,并对粗提物进行纯化。结果表明,巨尾桉叶皂苷的优化条件是:提取温度61.8℃,提取时间5.02 h,溶剂与巨尾桉叶的液料比为20.09∶1,皂苷的提取得率(g/g)为5.51%。提取物经大孔树脂-丙酮沉淀联用分离法纯化后皂苷含量由16.22%提高到50.35%。对粗提物、大孔树脂纯化物和大孔树脂吸附-丙酮沉淀纯化物进行抗氧化活性研究。结果表明,它们对DPPH自由基的最大清除率分别为83.02%、84.20%和85.62%,对过氧化氢的最大清除率分别为80.10%、55.02%和48.21%,对超氧阴离子自由基的最大清除率分别为16.62%、13.43%和10.01%。

巨尾桉光合特征与水分消耗的季节适应

使用Li-6400于旱季和雨季分别对云南省澜沧地区种植巨尾桉的净光合速率和蒸腾速率、气孔导度进行测定。研究发现:雨季巨尾桉光饱和点达1590μmol photon·m-2s-1,而旱季土壤水分不足时光饱和点仅867μmol photon·m-2s-1,光补偿点亦有下降。旱季气孔导度对蒸腾和光合的限制作用明显强于雨季。旱季巨尾桉气孔限制强度及蒸腾对光强变化的响应均与本地植物红木荷类似,而雨季巨尾桉的净光合速率远高于后者。巨尾桉具有与环境水分供应变化相协调的水分利用策略,旱季减少水分消耗以尽量节水,雨季则充分光合以获得更多生长。其类似本地植物季节变化的蒸腾特征和水分利用对策有利于维持群落地段的水分平衡。