Micropropagation of Elaeagnus angustifolia from mature trees

Multiple shoots were obtained from nodal segments of mature trees of Elaeagnus angustifolia L. cultured on MS medium (Murashige and Skoog 1962) supplemented with 0, 0.88 or 2.22 micro M N(6)-benzyladenine. When nodal segments taken from the in vitro proliferated shoots were cultured under the same conditions, additional multiple shoots were obtained. Rooting of the in vitro propagated shoots was achieved on full strength MS medium or on MS supplemented with 2.46 micro M indole-3-butyric acid. Regenerated plantlets were acclimatized and successfully transplanted to soil.     

Micropropagation of field tested superior Eucalyptus grandis hybrids

Three superior clones of Eucalyptus grandis hybrids were micropropagated through several steps. Five-year-old trees were girdled to induce juvenile sprouts. Cultures were attempted from mature branches and sprouts. Branches from mature trees were 100% contaminated while sprouts were only 40% contaminated. Pre-initiation hormone free medium and dark environment were used to screen for contaminants and to reduce production of phenolic compounds. Initiation of auxillary buds was achieved with modified MS plus 0.05 mg/l NAA and 0.5 mg/l BAR High multiplication rates were obtained on auxin-free medium with 0.6 mg/1 BAR Elongation of shoots was best on media with high auxin (2.5 mg/l of IBA) and cytokinin (1–1.5 mg/l of zeatin). Continual subculture on the multiplication medium improved rooting significantly. Up to 98% rooting was achieved on 1/4 MS with 2 mg/l IBA. Rooted propagules were successfully transferred to a mist greenhouse with 82% survival, and then to greenhouse conditions.     

提高桦木板材性能的研究

本文以提高桦木板材物理、力学性能指标,扩大其使用用途为目的,着重研究了桦木中施加强化剂后对其显微结构,物理、力学性能的影响,为今后扩大其木材利用率提供了一定的依据。     

Managing birch woodlands for the production of quality timber

Interest in silver birch (Betula pendula Roth) and downy birch(Betula pubescens Ehrh.) has greatly increased in recent yearspartly as a result of pressures to restore and expand nativewoodlands but also due to renewed interest in birch as a treecapable of producing quality timber. Despite the many advantagesof birch as a commercial timber tree—ease of establishment,fast growth on good sites, high value timber and a short rotation,it has a poor reputation in Britain largely as a result of thepoor form of the existing, mainly unmanaged resource. The followingpoints need to be considered if stands of quality birch treesare to be produced in an economical timescale. (1) Sites: silverbirch needs good sites that are relatively well drained withlight mineral soils. Downy birch does well on moist to wet sites.(2) Regeneration: natural regeneration through a shelterwoodis the preferred system of regenerating birch as some overheadprotection is beneficial to germination success. About 20–40seed trees should be left per hectare. Good ground preparationand control of grazing are essential. The vast majority of seedlingsare recruited in the first year of the regeneration cycle thereforeplanting should be considered if the initial regeneration successis poor. Direct seeding is also a successful method of regeneration.Birch readily regenerates naturally into suitably prepared openareas next to existing birch woods but these should not be toobig, e.g. gaps or strips 20–60 m wide have been suggestedin the literature. (3) Maintenance: density of regenerationneeds to be reduced to about 2500–3000 stems ha^–1by the time the trees are about 3–6 m tall. Birch seedlingsmust always be taller than the competing vegetation. (4) Thinning:thinning should begin when the mean height of the stand is about8–10 m. At this point at least half the number of treesshould be removed with the emphasis on retaining dominants andco-dominants of good form. The aim is to maintain about halfthe height of the tree as living crown to sustain a high rateof growth. Additional thinnings will be required at intervalsof 5 to 7 years and final thinning should leave around 300–500stems ha^–1. (5) Rotation: a rotation of 40–50 yearsis possible on good sites and perhaps 50–55 years on lessfavourable sites.     

Determinants of biomass production in hybrid willows and prediction of field performance from pot studies

Pot experiments are often performed to assess plant physiological traits and relationships among growth traits under controlled environments. However, the reliability of pot studies for predicting the growth and performance of trees in the field has rarely been rigorously assessed. We evaluated the suitability of pot experiments for predicting field performance, measured as shoot biomass production, by investigating determinants of growth in hybrid willows (Salix spp.) grown under various environmental conditions in the field, and by comparing the data with the results from a corresponding pot study. Biomass production in six hybrid willow clones, bred for use as bio-fuels, was assessed in three field trials located in central and southeastern Sweden throughout the first 3-year cutting cycle. The determinants of biomass productivity, measured as biomass allocation and nitrogen (N) economy, were identified in one of the field trials. Key traits for shoot biomass production in the field were total leaf area and total amount of N; plant N losses by shed leaves were only partly controlled by leaf-litter N concentration. These key traits were also obtained from the pot study and related to shoot biomass production and abscission-leaf N loss in the field. Total leaf area and total N pool of plants grown in pot experiments were good predictors of long-term biomass production in the field, whereas shoot biomass production, specific leaf area and tissue N concentration of pot-grown plants were less suitable as predictors of field performance. Relationships between the key traits and shoot biomass production were clone-specific, indicating the need for analysis of growth traits at the clone level if field performance of trees is to be evaluated based on data from pot studies. Nutrient loss components are important for tree performance in the long term and evaluations of nutrient loss characteristics at the individual-tree level should focus on nutrient pools lost rather than on nutrient concentrations in abscised plant parts.     

Stem radial CO_2 conductance affects stem respiratory CO_2 fluxes in ash and birch trees

The CO_2 released from respiring cells in woody tissues of trees can contribute to one of three fluxes:efflux to the atmosphere(E_A),internal xylem sap transport flux(F_T),and storage flux(DS).Adding those fluxes together provides an estimate of actual stem respiration(R_S).We know that the relative proportion of CO_2 in those fluxes varies greatly among tree species,but we do not yet have a clear understanding of the causes for this variation.One possible explanation is that species differ in stem radial CO_2 conductance(g_c).A high g_c would favor the E_A pathway and a low g_cwould favor the F_Tpathway.However,g_chas only been measured once in situ and only in a single tree species.We measured g_cusing two methods in stems of Fraxinus mandshurica Rupr.(ash)and Betula platyphylla Suk.(birch)trees in situ,along with R_S,E_A,F_T and DS.Stem radial CO_2 conductance was substantially greater in ash trees than in birch trees.Corresponding to that finding,in ash trees over 24 h,E_Aconstituted the entire flux of respired CO_2 ,and F_Twas negative,indicating that additional CO_2 ,probably transported from the root system via the xylem,was also diffusing into the atmosphere.In ash trees,F_T was negative over the entire 24 h,and this study represents the first time that has been reported.The addition of xylem-transported CO_2 to E_A caused E_Ato be 9% higher than the actual R_Sover the diel measurement period.Birch trees,which had lower g_c,also had a more commonly seen pattern,with E_A accounting for about 80% of the CO_2 released from local cell respiration and F_T accounting for the remainder.The inorganic carbon concentration in xylem sap was also lower in ash trees than in birch trees:2.7 versus 5.3 mmol L^-1,respectively.Our results indicate that stem CO_2 conductance could be a very useful measurement to help explain differences among species in the proportion of respired CO_2 that remains in the xylem or diffuses into the atmosphere.     

Susceptibility of adult trees of the endangered species Pinus armandii var. amamiana to pine wilt disease in the field

Adult trees of Pinus armandii var. amamiana (PAAm) and P. thunbergii grown in the field were inoculated with 100000 or 1000 of the nematode Bursaphelenchus xylophilus to evaluate their susceptibility to pine wilt disease. PAAm trees inoculated with 100000 nematodes started to show disease symptoms 2 weeks after inoculation, and all died within 29 weeks. Although the PAAm trees inoculated with 1000 nematodes tended to show delayed disease symptoms compared with those inoculated with 100000 nematodes, all of them died within 33 weeks after inoculation. All P. thunbergii trees inoculated with 1000 nematodes had died 6 weeks after inoculation. In the nematode-inoculated PAAm trees, death of branches distal to the nematode inoculation site was the first visible symptom, followed by the systemic discoloration of needles, whereas the whole tree wilted simultaneously in P. thunbergii trees. In nematode-inoculated PAAm trees, the period from inoculation to death was longer than that in P. thunbergii. These results suggest that adult PAAm trees are susceptible to pine wilt disease, but are less vulnerable than P. thunbergii.     

柏木优树家系苗期生长表现

以来自重庆市和浙江省千岛湖的4个种源34个柏木优树家系2年生苗为材料,研究家系和种源间苗期生长性状的差异性。结果表明:苗高与地径在家系和种源间均存在极显著差异,家系间变异系数分别为11.37%和18.89%,种源间变异系数分别为7.25%和12.58%,说明柏木的苗高与地径在家系和种源间存在较为丰富的变异,具有选育潜力。按15%的入选率,筛选出5个柏木苗期速生优良家系丰05、丰03、丰04、丰01和忠13。5个优良家系平均苗高和地径分别为79.04 cm和9.99 mm,高出参试家系平均苗高和地径的15.43%和31.37%,比对照高19.94%和49.15%。     

园林苗木容器栽培的城市环境效应

园林苗木容器栽培是一种十分有效的栽培方式,必将成为苗木栽培的主要方式.本文从园林苗木容器栽培的城市环境功能方面阐述了容器栽培相比于露地栽培的独到优势,以期进一步推动我国园林苗木容器栽培产业的发展.     

The growth and production modeling of individual trees of Eucalyptus urophylla plantations

Individual tree models(ITMs) are classified as growth and production models for projecting current and future forest stands. ITMs are more complex than other growth and production models, show a higher level of detail and, consequently, produce a better modeling resolution. However, the accuracy and efficiency of ITMs have not been properly assessed to date. In this study, we estimated the growth in height, diameter, and individual tree volume of a Eucalyptus urophylla plantation by applying an ITM. We used a continuing forest inventory dataset in which 1554 individual trees within 29 permanent plots were measured in the field over a 6-year period(24 to 72 months). Each individual tree volume was estimated for future tree age. To achieve this, we adjusted the model to predict the height and diameter growth, and the probability of mortality as a function of the competition index. The ITM accuracy was assessed based on the analysis of variance results and, subsequently, the multiple mean comparison test at the 5% significance level. The tree volumes predicted by the ITM for the forest stand aged 72 months,beginning at ages 24, 36, 48, and 60 months, were compared to the field measured tree volume acquired from the 72-month forest inventory that was used as the reference age. Estimated and observed tree volumes were similar when the estimation was based on the 48-month forest plots. These results might help to reduce financial costs of forest inventory because the ITM produces accurate future predictions of forest stand stocks. Our estimated ITM for Eucalyptus plantations using measurement intervals up to 2 years is recommended because it significantly reduced the projected volume discrepancy compared to the field measurements.     

吴江市果树生产现状及发展对策

通过分析吴江市现有果树生产、经营上存在的优良品种少、生产技术落后、经营规模小而散等现状,提出了今后果树产业发展要走规模化、品牌化、科技化生产经营之路。     

Micropropagation and tissue culture of Eucalyptus-a review

Micropropagation has the potential to provide very high multiplication rates of selected tree genotypes, with resulting short-term silvicultural gains. Aseptic cultures have been established from seeds, seedlings, shoots, flowers and lignotubers. Callus cultures have been established from a wide range of tissue sources for at least 30 species of Eucalyptus. Plant regeneration from callus was successful for 12 of these species. Micropropagation through axillary proliferation, or adventitious shoot proliferation on nodal explants, or both, has been successful. An agar-based medium of Murashige and Skoog with a low auxin/cytokinin ratio is most commonly used for shoot multiplication. Vitrification and shoot senescence remain problems. Gibberellic acid was added in some media to stimulate shoot elongation. Various media are used for in vitro root initiation. Suspension and protoplast cultures have been achieved and plants have been regenerated from protoplasts. In vitro techniques are presently being applied to Eucalyptus to achieve genetic transformations.     

Loblolly pine cutting morphological traits: Effects on rooting and field performance

Shoot cuttings were harvested fromfour-year-old, loblolly pine hedges in March andSeptember of 1987, and placed into a series offactorial combinations of cutting length, diameterclass, and the presence/absence of a terminal bud toassess effects on rooting and field performance.Average rooting in the March trial was 50 percent andonly 20 percent for the September trial; however, thebest treatment in March yielded 100 percent rooting.Terminal bud status did not appear to influencepercent rooting. Shorter cuttings (5.1 or 7.6 cm)with an average diameter of 2 or 3 mm tended to rootbetter and develop more roots. Field performance ofthe rooted cuttings through age five suggests that theoriginal cutting does not require a terminal bud, butthe best set of morphological traits differ dependingon bud status. Considering both rooting ability andfield growth with an original tip bud present, thebest cutting dimensions were 5.1 or 7.6 cm long and 2or 3 mm in diameter. Without a tip bud present,cutting dimensions were restricted to 7.6 or 10.2 cmlong and 3 mm in diameter. Number of main roots wasa weak predictor of tree height or dbh at age five.     

Shade trees: a determinant to the relative success of organic versus conventional coffee production

Greater understanding of the influences on long-term coffee productivity are needed to develop systems that are profitable, while maximizing ecosystem services and lowering negative environmental impacts. We examine a long-term experiment (15 years) established in Costa Rica in 2000 and compare intensive conventional (IC) coffee production under full sun with 19 agroforestry systems combining timber and service tree species with contrasting characteristics, with conventional and organic managements of different intensities. We assessed productivity through coffee yield and coffee morphological characteristics. IC had the highest productivity but had the highest yield bienniality; in the agroforestry systems productivity was similar for moderate conventional (MC) and intensive organic (IO) treatments (yield 5.3 vs. 5.0 t ha^?1 year^?1). Significantly lower yields were observed under shade than full sun, but coffee morphology was similar. Low input organic production (LO) declined to zero under the shade of the non-legume timber tree Terminalia amazonia but when legume tree species were chosen (Erythrina poepiggiana, Chloroleucon eurycyclum) LO coffee yield was not significantly different than for IO. For the first 6 years, coffee yield was higher under the shade of timber trees (Chloroleucon and Terminalia), while in the subsequent 7 years, Erythrina systems were more productive; presumably this is due to lower shade covers. If IC full sun plantations are not affordable or desired in the future, organic production is an interesting alternative with similar productivity to MC management and in LO systems incorporation of legume tree species is shown to be essential.     

Field performance of Pinus contorta trees propagated vegetatively via adventitious buds

Abstract

Pinus contorta plants regenerated from adventitious buds induced on zygotic embryos were planted in a field trial where growth, straightness and flowering were followed over 7 years. Seedlings were taller than the plants derived from adventitious buds at the start of the field trial. Adventitious plants did not catch up with seedlings in height after 7 years in the field, but the relative height growth was equal. The higher frequency of plagiotropic growth that was displayed by adventitious plants the first year in the field was not reflected by differences in the frequency of basal sweeps 6 years later. However, the frequency of crooked stems was comparatively high but similar among the plant types. Flowering was more abundant for the seedlings than for adventitious plants. Taken together, the results show that P. contorta can be cloned via adventitious buds from zygotic embryos, and that the resulting plants show satisfactory growth for inclusion in breeding.     

Evaluation of 15 leguminous trees and shrubs for forage and wood production in Tanzania

Fifteen leguminous tree and shrub species were evaluated for production of fuelwood, forage and forage nutrient concentrations. When assessed for survival, growth and biomass yields after 30 months, Acacia crassicarpa, A. leptocarpa, A. auriculiformis, A. torulosa and A. aulacocarpa were the most outstanding. The nutrient concentrations in edible fractions varied greatly among the accessions. While the results indicate that most of the species tested could not supply adequate minerals when used as sole feeds, they could supply valuable supplemental fodder. This revised version was published online in June 2006 with corrections to the Cover Date.     

Stock quality and field performance of Pinus patula seedlings produced under two nursery growing regimes during seven different nursery production periods

Two types of containerized P. patula seedlings, referred to as hard and soft seedlings, were raised by droughting and different fertilizer applications. Hard seedlings were raised by applying half the water and a quarter of the fertilizer (0.01 g per seedling 21%N:7.1%P:14.2%K) applied to the soft seedlings. At the end of the nursery cultural treatments the two types of seedlings were morphologically distinct. Hard seedlings had lower heights, height to root collar diameter ratios and seedling dry masses than soft seedlings, but mortality was similar for both seedling types when planted during seven different production periods within the planting season on three sites which differed climatically and geologically. Correlations between mortality and height to root collar diameter ratio (r = 0.76), root to shoot ratio (r = 0.83) and root growth potential (r = --0.69) were obtained indicating that grading of seedlings on these parameters may improve survival. However, it was evident that survival could be significantly improved by identifying the best time of year and conditions for planting, as well as improving stock quality.