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 o...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.展开更多
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...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.展开更多
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...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.展开更多
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 tree...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.展开更多
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 plant...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.展开更多
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 mult...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.展开更多
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 concentrat...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.展开更多
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 ...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.展开更多
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 prop...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.展开更多
基金supported by the Sci-technology program of Guangxi Province(No.Guikezhong 1347001)
文摘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.
基金financially supported by the Special Fund for Forest Scientific Research in the Public Welfare(201404113)the 111 Project(B13007)the Program for Changjiang Scholars and Innovative Research Team in University(IRT13047)
文摘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.
文摘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.
基金China-ACIRA (Australian Centre for International Agricultural Research) cooperation project (FST/1999/095) Chinese"948" Project (No. 2005-4-73).
文摘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.
文摘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.
文摘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.
文摘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.
基金supported by the New Century Excellent Talents in University - "Study on characters and optimal matching of woodsolar drying latent heat storage system"
文摘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.
文摘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.
