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1.
The flavonoids content and its composition in Ginkgo (Ginkgo biloba L.) leaves are affected by environmental factors such as temperature and soil moisture. Here we performed experiments in phytotron using 2-year-old Ginkgo seedlings to explore the effects of temperature and soil moisture on flavonoids content, enzymes related to flavonoids biosynthesis such as phenylalanine ammonia-lyase (PAL), cinnamate-4-hydroxylase (C4H) and p-coumarate CoA ligase (4CL), soluble sugar and protein content. We found that temperature and lower soil moisture had significant effects on these parameters. The effects of temperature on flavonoids content, the activity of C4H and 4CL and soluble sugar content were greater than that of soil moisture. The total flavonoid content, the activity of PAL, C4H and 4CL, soluble sugar content were higher in lower temperature regime 15 °C (daytime)/5 °C (nighttime) and lower soil moisture (30–35 % of field capacity), but higher temperature was beneficial to the accumulation of soluble protein. This indicates that increasing of soluble sugar content and the activity of PAL, C4H and 4CL are beneficial to flavonoids biosynthesis and accumulation in the Ginkgo leaves, while increasing of soluble protein is adverse to flavonoids biosynthesis. Because lower temperature and soil moisture are favorable to flavonoids biosynthesis, we can take some silvicultural steps to increase flavonoids production in Ginkgo plantation, such as establishing leaf-harvest plantation at lower temperature zone, reducing irrigating before harvesting leaves.  相似文献   

2.
Field experiments have been carried out to evaluate the potency of the biological control agentBacillus thuringiensis (Dipel), the pyrethroid Fenvalerate and their combinations for the control of the lesser cotton leafwormSpodoptera exigua on soybeans in Qualubia governorate. Molasses was combined with all treatments to enhance their effectiveness. One spray application with either Dipel or Fenvalerate showed an obvious reduction in larval counts ofS. exigua, associated with a significant increase in the crop yield but in varying degrees, in correlation with the tested dose. Treatments with combinations of both biological and chemical insecticides at the lowest tested doses (62 g ofB. t. +50 ml of Fenvalerate/feddan) showed to be highly potential, and caused 2.8 fold increase in the crop yield. It may be recommended that a combination of both preparations may be used for the control ofS. exigua.  相似文献   

3.
Maritime pine (Pinus pinaster Ait.) is an important timber and pulpwood species covering about 4 million ha in Portugal, Spain and France. This work studied the cross-sectional distribution of heartwood and sapwood along the stem using 3D modelling on 20 trees. The target was to assess the potential of this species for the industrial production of heartwood sawn products. The maritime pine stems were characterized by wide sapwood of 10 cm, in average, and the presence of heartwood at all height levels with constant diameter up to 35 % tree height, decreasing afterwards. In the radial section, the heartwood follows a circumferential-like shape which changes along the stem. Pith eccentricity index values were low and homogeneous regarding to stem and higher for heartwood. Heartwood cross-sectional shape was constant up to 45 % of total height of the tree and more elongated upwards. The constant heartwood diameter, low taper and pith eccentricity index, and an approximate circular shape up to 10 m height indicated these species’ potential to produce solid wood products made out of heartwood.  相似文献   

4.
The aim of the present work was to estimate the basic wood density of Mimosa tenuiflora by using near-infrared spectroscopy (NIRS). Fifty-eight wood samples representing sapwood, heartwood and pith were evaluated by gravimetric method and NIRS together with wavelength selection methods. A comparison was made among several multivariate calibration techniques and algorithms for preprocessing and variable selection of data, including full-spectrum partial least squares (PLS), interval PLS, backward interval PLS, synergy interval PLS, genetic algorithm-PLS and successive projections algorithm for interval partial least squares (iSPA–PLS). Finally, the results obtained using iSPA–PLS model for the root mean square error of calibration and prediction were 0.0383 and 0.0166 g/cm3, respectively. A t-test was performed to compare the results of the models with each other and with a reference method. NIRS and iSPA–PLS can be used to predict basic density of Mimosa tenuiflora [Willd.] Poiret wood samples rapidly. In addition, the basic density could also be predicted with only 17 wavelengths in the range from 2,090 to 2,208 nm that should allow for measurement of this parameter using handheld NIR spectrometer.  相似文献   

5.

Context

Reliable information on tree stem diameter variation at local spatial scales and on the factors controlling it could potentially lead to improved biomass estimation over pine plantations.

Aims

This study addressed the relationship between local topography and tree diameter at breast height (DBH) within two even-aged radiata pine plantation sites in New South Wales, Australia.

Methods

A total of 85 plots were established, and 1,302 trees were sampled from the two sites. Airborne light detection and ranging (LiDAR) was used to derive slope and aspect and to link them to each individual tree.

Results

The results showed a significant relationship between DBH and local topography factors. At both sites, trees on slopes below 20° and on southerly aspects displayed significantly larger DBHs than trees on steeper slopes and northerly aspects. Older trees with similar heights also exhibited a significant relationship between DBH and aspect factor, where greater DBHs were found on southerly aspects.

Conclusions

The observed correlation between tree DBH and LiDAR-derived slope and aspect could contribute to the development of improved biomass estimation approaches in pine plantations. These topographical variables are easily attained with airborne LiDAR, and they could potentially improve DBH predictions in resource inventories (e.g. stand volume or biomass) and support field sampling design.  相似文献   

6.
Agroforestry with its outstanding variety of systems and technologies has been practiced in all parts of the world since times immemorial. Its worldwide recognition, scientific promotion and application in rural development strategies in the tropics, however, ‘exploded’ with two events: the foundation of the International Council for Research in Agroforestry (ICRAF), 1977 and the Eighth World Forestry Conference in Jakarta, 1978. This is important to be recalled at the occasion of the Ninth World Forestry Congress to be held in Mexico this year. Agroforestry's holistic approach to solving land use problems under prevailing conditions and constraints of different humid, semiarid and mountainous regions has gained importance and produced first remarkable results with regard to increasing the human-ecological carrying capacity. Forestry is gaining from the newly promoted strategies of integrated land use in various ways: less pressure on forest resources and thus less destruction of forest vegetation, additional lands for wood production outside the forest estate, cooperation instead of confrontation with other target groups, and an expanded multiple-use concept increasing the value of marginal forest lands. Agriculture and livestock management are improved by various environmental benefits of the forest component and by the availability of forest products within agroforestry systems. First achievements over the past seven years have been encouraging in many instances. Much more, however, remains to be done in future.  相似文献   

7.
A review of research on the nun moth (Lymantria monacha L.) 1973–1984 in Czechoslovakia conducted with pheromone traps is given. By using this method many new results on bionomy, ecology and gradology of this pest could be obtained.  相似文献   

8.
The reactions of Japanese cedar and Japanese beech in a pyridinium-based ionic liquid, 1-ethylpyridinium bromide ([EtPy][Br]) were studied. Japanese beech was more easily liquefied than Japanese cedar. Hemicellulose is liquefied rapidly, lignin more slowly, while cellulose is partially liquefied. X-ray diffraction analyses on the [EtPy][Br]-insoluble residues revealed that the crystalline structure of cellulose is maintained even after treatment. The difference in liquefaction can be explained by chemical structural differences between softwood and hardwood lignins and hemicelluloses.  相似文献   

9.
Bamboo fibers were mechanically extracted from raw green bamboos by crushing, rolling, and combing techniques with 1,4-butanediol as a solvent. The morphology of the bamboo fibers thus obtained was analyzed. The bamboo fibers were treated with isocyanatoethyl methacrylate (IEM) in the presence of dibutyltin dilaurate as a catalyst, to improve the interfacial adhesion between the fibers and unsaturated polyester (UPE) resins. The bamboo fibers reinforced UPE composites were prepared by hand lay-up compression molding. FTIR, XPS, and NMR analyses indicated that the IEM was covalently bonded onto the bamboo fibers via carbamate linkages. The IEM treatments significantly increased the tensile strength, flexural strength, flexural modulus, and water resistance of the resulting composites and yet decreased the impact strength of the composites. The SEM images of the tensile-fractured surfaces of the IEM-treated bamboo fibers–UPE composites revealed that the fiber treatments markedly improved the interfacial adhesion between the bamboo fibers and UPE resins.  相似文献   

10.
The focus of this study was to investigate the chemical and colour changes occurring at different exposure times on artificially photo-irradiated surfaces of normal and red heartwood in beech in order to understand the mechanisms that cause the changes and to evaluate the possibility of usages of beech not only for energy production purposes. In this sense, surface colour modifications are of crucial importance to define the commercial value of beech wood. The artificial photo-irradiation of the wood samples was performed in a Solar Box, equipped with an ultraviolet filter that cuts off the spectrum at 280 nm. Reflectance spectrophotometry and Fourier transform infrared (FTIR) spectroscopy were used to assess artificial sunlight influence. The experimental data were statistically treated to evaluate their significance. Colour monitoring revealed that wood surface colour undergoes an important variation due to photo-irradiation, occurring within the first 24–48 h. Moreover, it was found that the chromatic coordinates (L*a*b*) in normal wood and in red heartwood tended to similar values after 504 h. FTIR spectroscopy allowed for investigating the rate of photodegradation of wood surface due to oxidation reactions of wood components. The results were validated by statistical analysis applied both to the colorimetric and spectroscopic data.  相似文献   

11.
A trial demonstrating an establishment and maintenance technique forPinus caribaea var hondurensis in an agroforestry land use system on the Atherton Tableland, north east Australia, is described. The establishment of the tree component involves mechanical cultivation and the application of herbicides which in combination are technically feasible and acceptable to a landholder who wishes to integrate pine trees and pasture grasses. The cost of establishment and maintenance of the pines up to age 39 months was calculated at $A809 ha?1 (1986 values). This includes the cost of thinning. The sale of some thinnings for Christmas trees realised a net profit of $A564 from 300 trees ($A188 ha?1). At age 38 months the stand had a stocking of 254 trees ha?1, a mean height of 6 m and a mean diameter at breast height of 12.1 cm. The growth compares favourably with other plantation grownPinus caribaea var hondurensis on the Atherton Tableland.  相似文献   

12.
The global spread of the Asian tiger mosquito Aedes albopictus, an urban pest as well as a vector for arboviruses, is a threat for public health. As control measures include the use of insecticides such as the pyrethroid λ-cyhalothrin, it is crucial to assess their efficiency and their potential impact on the biodiversity especially under climate change conditions. To evaluate the environmental risk, biotests are well established for non-target organisms but not yet for mosquitoes. We therefore developed a full-lifecycle biotest for mosquitoes kept under quarantine conditions based on the OECD guideline 219. Therewith we tested the effect of temperature and nutrition on the ecotoxicological response to λ-cyhalothrin on the mosquitoes Ae. albopictus and Culex pipiens by assessing sublethal and life history parameters. The efficiency of λ-cyhalothrin decreased in both mosquito species with increasing temperature and changed with feeding protocol. At effective concentrations for potential mosquito control in surface waters, λ-cyhalothrin poses a high risk for indigenous aquatic key role species inhabiting the same microhabitats. Those aspects should to be taken into account in vector control strategies.  相似文献   

13.
During spring and summer 1990 observations on the biology of the ash sawfly,Tomostethus nigritus F. were made and control options discussed. The sawfly overwinters as an co- or pronymph in the soil, and pupates in earlys spring. The tlight period lasted for about 3 weeks. The larvae fed on the leaves till June. Injecting the systemic insecticide Carbicron 50 SCW (Dicrotophos) was successful.  相似文献   

14.
Lepidosaphes beckii Newm. (Hom., Diaspididae) andCeroplastes floridensis Comst. (Hom., Coccidae), are dominant pests on citrus trees (Citrus sinensis), in Alexandria district. The population fluctuations of the parasites of both insects were studied during a whole year. Six species of hymenopterous primary parasites together with one secondary parasite were found onL. beckii. These species wereAphytis lepidosaphes Compere,A. bispanicus Compere,Encarsia (Prospaltella) spp.,Aspidiotiphagus citrinus Craw,Aphytis lingnanensis Compere, and the secondary parasiteMarietta javensis Howard.A. lepidosaphes was the most common parasite onL. beckii. ConcerningC. floridensis, four species of hymenopterous parasites were found, namelyTetrastichus ceroplastae (Girault),Aspidiotiphagus citrinus Craw,Metophycus flavus (Howard), andMicroterys flavus (Howard).  相似文献   

15.
Variability of the compression properties of cork   总被引：1，自引：0，他引：1  
The variability of the compression properties of cork was determined after field sampling covering the main production area in Portugal (10 sites) with samples taken from 20 trees per site at the time of cork stripping. In all cases, cork showed compressive stress–strain curves typical for cellular materials, which are characterized by an approximately “elastic” region up to a 5 % strain, followed by a large plateau up to 70 % strain caused by progressive buckling of cell walls, and a steep stress increase for higher strains corresponding to cell collapse. The radial direction of compression offered higher strength. The Young’s moduli averaged 10.4 and 9.2 MPa for radial and non-radial directions, respectively, spreading from 3.5 to 22.5 MPa for the non-radial and 4.2 to 21.5 MPa for the radial directions. The geographical location of cork production was the major factor of variability. Density, annual growth ring width and chemical composition influenced compression. Cork samples with higher density showed overall larger resistance to compression. The energy absorbed per unit volume to achieve the maximal deformation with full densification of cork is higher when the average annual ring width is smaller. Cork samples with relatively higher suberin content required less stress for deformation. The results encompass the natural variability of cork and are the most extensive to characterize cork. They allow a better insight into the differences that may explain the variation in cork properties and strengthen its use either in the known applications, i.e. as a sealant, or in novel applications.  相似文献   

16.
Part I of this article dealt with the theoretical background of ergonomics and its role in rural development. This second part points out the economic and social advantages of ergonomically-orientated planning of rural development. Outside the industrial world ergonomics is still a largely hypothetical science. Research and information needs prevail for the derivation of ergonomic guidelines for agroforestry landuse in tropical and subtropical regions. Climate, nutrition and skills are decisive factors in determining the sustainable work capacity of people. Agroforestry with its increased use of human labour must fail if economic goals cannot be reconciled with ergonomic requirements, particularly physiologically balanced work designs.  相似文献   

17.
Spodoptera exempta (Wlk.) is recorded every year in the Republic of Yemen. Based on the use of pheromone traps, a very simple but effectively applicable monitoring and forecasting system was developed. Areas from which infestations have been reported and the frequency of attacks are mapped in detail. The monthly distributions and frequencies of incidence are presented in two tables. The range of recordedS. exempta moths is illustrated and the number of outbreaks for the last 32 years described.  相似文献   

18.
Agroforestry Systems Inventory   总被引：2，自引：0，他引：2  
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19.
In Amazonian Ecuador, studies are being realized to intensify fallow periods by grazing African tropical forest type sheep (Red Afro-Colombian X Barbados Black Belly) on Asian tropical forest legume cover forage (Desmodium ovalifolium) under American tropical forest legume fuelwood trees (Inga edulis). The specific approach represents an innovative effort to address the complex problems associated with the pernicious use of less fertile lands by small-scale farmers and graziers in the humid tropics. The technologies developed are closely compatible with traditional socio-cultural patterns. For example, shifting cultivators are encouraged to plant contour strips of legume fuelwood trees in their cassava fields. With the cassava harvest, legume cover forage is planted between the fuelwood trees, to be grazed later by tropical forest sheep. Forage and fuelwood legumes increase soil aeration, organic matter, nitrogen and available phosphorus, control soil erosion and leaching, as well as provide a break in cropping that checks insect, disease and weed build-ups. Tropical forest sheep improve soil fertility by depositing organic matter which stimulates legume/Rhizobium symbiosis and by supplying fecal microorganisms which mineralize crop residues. In addition, tropical forest sheep cause little soil compaction and erosion, produce high quality food protein from legume cover forage, as well as generate cash income, capital and employment for small-scale farmers. Tropical forest sheep on legume forage/fuelwood fallows not only intensify land use under shifting field cultivation, but also form the basis for rehabilitating already degraded lands for further foodcrop production.  相似文献   

20.
Influences of fiber orientation and milling on wood cellulose crystallinity were studied using jack pine wood. The fiber orientation effects were measured by sampling rectangular wood blocks in radial, tangential, and cross-sectional orientations. The influence of milling was studied by analyzing the unsieved and sieved milled wood fractions (all <1,000 μm). Fiber orientation effect was manifested in both X-ray and Raman measurements and was dependent upon the orientation of the sampled wood blocks. In Raman, the observed crystallinity was similar between the blocks sampled on the tangential and the radial faces. However, the estimated values were 5.5 % lower compared to that measured in a powdered sample pellet. Moreover, in these sampling modes, the orientation of the block with respect to the direction of the electric vector of the laser made a difference only for the tangential mode of sampling. When a wood block was sampled on the cross-sectional face, the observed Raman crystallinity was 3.9 % higher from that of the pellet. The observed crystallinity did not significantly differ with change in sample orientation with respect to the electric vector direction. In contrast, the Segal-WAXS study of the blocks indicated that compared to the pellet, the estimated crystallinities in the radial, tangential, and cross-sectional sampling modes were 5, 2, and 11 % lower, respectively. This suggested that the radial and the tangential faces of the blocks can be used to estimate the crystallinity of wood. With regard to the effect of milling on Raman and Segal-WAXS estimates, the wood crystallinity did not depend upon the particle sizes of the fractionated samples and was similar to that of the original unfractionated ground wood.  相似文献   

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