High resolution temporal variation in wood properties in irrigated and nonirrigated Eucalyptus globulus

? Environmental determinants of wood properties variation were examined in Eucalyptus globulus, a globally important hardwood plantation species, in southern Tasmania, Australia.

? Radial variation in wood properties, measured with the SilviScan system, were re-scaled from distance to time abscissa using stem radial growth data measured with dendrometers. With this re-scaled data it was possible to evaluate how water availability and temperature affected wood density, microfibril angle (MFA) and fibre and vessel transverse dimensions in irrigated and non-irrigated trees.

? Wood density, fibre radial diameter and MFA were sensitive to water availability. Wood density increased and fibre radial diameter decreased in response to reduced water availability. When high water availability was maintained, wood density was negatively correlated with temperature. Together, temperature and soil matric potential explained about 60% of temporal variation in wood density variation. In contrast MFA was not related to temperature but decreased with increasing water stress. Slower growing trees also had lower MFA than faster growing trees. Slower growing trees had a larger number of vessels per unit area of wood than faster growing trees within this even aged stand. However, vessel radius to the 4th power was significantly higher in faster growing trees than in slower growing trees.

? Overall, E. globulus wood properties were sensitive to temporal changes in environmental conditions (particularly water availability) and associated growth rates. The data provided support for the hypothesis that growth rates are hydraulically mediated.

     

Assessing genetic variation to improve stem straightness in Eucalyptus globulus

Context

Stem straightness is an important trait for growers and processors of Eucalyptus globulus logs for solid-wood products.

Aims

The aims of the study were to determine the extent of genetic variation in stem deviation from straightness in E. globulus and assess the utility of a six-point subjective scoring method as a selection criterion for stem straightness.

Methods

Two E. globulus progeny trials, grown under solid-wood product regimes, were studied. At age 9 years (post-thinning), stem straightness was measured using both image analysis and a six-point subjective scale. Diameter at breast height (DBH; 1.3 m) was measured at both age 5 (pre-thinning) and age 9 years.

Results

Significant additive genetic variation was observed. Strong, positive and significant additive genetic correlations were observed between the stem straightness assessment methods and between DBH at ages 5 and 9 years. Significant positive genetic correlations were shown between subjectively scored stem straightness and DBH at both ages 5 and 9 years.

Conclusion

The six-point subjective scoring method is a cost-effective selection criterion for stem straightness in E. globulus. The image measurement technique may be applied where objective estimates of stem straightness are required, for training purposes and to verify subjective scores.     

Wood anatomy and biometric parameters variation of Eucalyptus globulus clones

Variation in wood anatomy and biometric variables was studied in 14 7-year-old Eucalyptus globulus clones grown in a clonal trial in Arauco, Bio-Bio Region, Chile. Biometric characteristics were measured for each tree and the anatomical variables were measured at three radial positions by image analysis on transverse microsections cut from radial increment cores sampled at breast height. Results showed, that among clones wide ranges of variation were found for vessel frequency, vessel area and vessel coverage. However, narrow ranges of variation were found for fiber wall thickness, fiber diameter and lumen diameter. From pith to bark, mean vessel area and vessel coverage increased gradually, whereas the vessel frequency decreased. The fiber wall thickness did not differ significantly from pith to bark. Mean fiber and lumen diameters showed the same radial pattern, increasing from pith to the midpoint of the radius to reach a plateau close to the bark. Furthermore, important commercial volume gains that can exceed 100% were found. Considering the commercial importance of tree volume, vessel and fiber anatomy in the pulping and papermaking process, it is suggested that the information given in this study may be used as an additional criteria for the selection of E. globulus.     

Foliar nutrient retranslocation in Eucalyptus globulus

We measured patterns of change in concentrations and contents of nitrogen, phosphorus, potassium, magnesium and calcium in fully expanded leaves of young Eucalyptus globulus (Labill.) trees growing in a plantation in southeastern Australia, over a 12-month period beginning at the onset of spring. There was significant net retranslocation of mobile nutrients on a seasonal basis from green leaves, coinciding with continued growth and production of foliage. There was a close positive relationship between initial nutrient content (N, P and K) of the leaf and amount retranslocated, and a tight coupling between N and P retranslocated from leaves. Net retranslocation was significantly correlated with basal area growth increments. Artificial shading of leaves resulted in senescence and reduction in leaf mass. It also induced retranslocation of N, P and K from leaves of different ages and from different position in the canopy. Although the mechanisms underlying the effects of shading intensity on these changes were not elucidated, shading provided an experimental tool for studying retranslocation. Comparison of the results with published data for Pinus radiata (D. Don) grown in the same environment indicated a similarity between the species in patterns of change in foliar nutrient contents and in factors governing foliar nutrient retranslocation, giving rise to unifying principles.     

Patterns of longitudinal within-tree variation in pulpwood and solidwood traits differ among Eucalyptus globulus genotypes

Wood discs were sampled from 6 heights up the stem of 248 trees representing 10 subraces and 116 families grown in an E. globulus base-population progeny trial. The lower stem had the least favourable wood properties for kraft pulpwood and most solidwood applications: bark was thickest, basic density was lowest and kino, decay and shrinkage traits were greatest at or below 12% of tree height. Significant genetic differences at the subrace level were revealed in diameter, bark thickness, basic density, decay and gross shrinkage and at the family within subrace level in diameter, basic density and decay. However, subrace-by-height-category interactions in bark thickness, basic density, decay and gross shrinkage indicated that differences among subraces were dependent on height in these traits. Examination of longitudinal trends revealed some evidence that the zone of thick basal bark extended further up the stem in thicker-barked subraces and that the Southern Tasmania subrace might be less effective than other subraces in restricting the longitudinal spread of decay after infection.     

Teratosphaeria gauchensis associated with trunk,stem and foliar lesions of Eucalyptus globulus in Portugal

Teratosphaeria gauchensis and T. zuluensis both cause a stem canker of eucalypts that leads to serious damage in various parts of the world. Until recently, this disease was unknown in Portugal. Nevertheless, severe damage to Eucalyptus globulus has been observed in Portugal since 2006 when symptoms appeared as necrotic spots on young green stems and leaves, twig lesions, and dark oval‐shaped lesions on stems and trunks. The isolates from affected E. globulus tree plantations were identified using sequence data of the ITS1‐5.8S‐ITS2 and EF‐1α clusters, together with morphological characteristics. Based on these results, the causal organism was identified as T. gauchensis, which represents the first report of this pathogen from Portugal.     

蓝桉、直干桉综合丰产技术试验示范

试验林采用正交设计，因素为树种、整地方式、密度、施肥，各因素取３个水平，３次重复。用生长量、生物量与投入产出进行评价。试验结果：３．５年生蓝桉、直干桉幼林最佳处理平均高９．５ｍ，平均胸径８．９ｃｍ，每ｈｍ２蓄积量７０．５１２６ｍ３，最佳处理比最差处理树高大２８．４％，胸径大３４．９％，蓄积量大１８３％。用已取得的技术成果营造的示范林，３．５年生平均高９．８ｍ，平均胸径６．５ｃｍ，累计产桉叶２．４３万ｋｇ／ｈｍ２，３年生左右，通过桉油及薪柴的收入可以回收全部造林及加工成本。     

蓝桉组织培养的研究

用蓝桉（Ｅｕｃａｌｙｐｔｕｓｇｌｏｂｕｌｕｓ）离体芽器官诱导培养，分化形成丛生芽，年繁殖系数３￣（１２）。０．１～０．５ｍｇ／Ｌ的６－ＢＡ或０．５～０．８ｍｇ／Ｌ的ＫＴ诱导外植体（带节茎段）腋芽萌动的效果最佳，诱导率分别达８０．３％和８１．５％。１．５～２０ｍｇ／Ｌ的６～ＢＡ或２０～２．５ｍｇ／Ｌ的ＫＴ分别与０．５～１．０ｍｇ／Ｌ的ＮＡＡ组合，对于促进腋芽分化形成丛生芽及继代培养中芽的增殖具有最佳效果。培养基中的无机盐浓度、蔗糖含量对蓝桉试管苗的生根具有显著影响；ＩＢＡ促进蓝桉试管苗的生根。至目前为止，在１／２ＭＳ无机盐培养基＋ＩＢＡ１．２～１．４ｍｇ／Ｌ＋Ｓ５ｇ／Ｌ中诱导生根，生根率最高可达２６．４％。     

Mineral nutrition and adventitious rooting in microcuttings of Eucalyptus globulus

We characterized the adventitious rooting response of Eucalyptus globulus Labill. to various concentrations of calcium, nitrogen, phosphorus, iron, manganese, zinc, boron and copper. The parameters analyzed were percent rooting, root number, root length and mean rooting time. Root number and root length were significantly affected by mineral nutrition, whereas mean rooting time and rooting percentage seemed to be closely related to auxin availability. Root number was affected by calcium, nitrogen source and zinc, whereas root length was influenced by concentrations of phosphorus, iron and manganese, and by nitrogen source. Based on these results, we evaluated various combinations of several concentrations of these minerals in each rooting phase. Cuttings that were rooted in an optimized mineral nutrient medium and acclimatized to ex-vitro conditions for two months showed significantly higher survival after transplanting and drought stress than cuttings rooted in basal medium and treated in the same way.     

Studies on Dual Mycorrhizas of Eucalyptus globulus and E

This paper represents the first part of the results from a glasshouse experiment designed to compare the competition of ECM and VAM fungi on root colonization and effects on growth of two Eucalyptus species　（E．globulus and E．urophylla）．One ECM fungus（Laccaria lateritia）　and three VAM fungi belonging to genera Glomus，Acaulospora and Scutellospora，along with field soil as well，were used to inoculate Eucalyptus seedlings alone or in combination．Both ECM and VAM fungi colonized and formed mycorrhizal associations on roots of inoculated seedlings，though infective rates of VAM and ECM tips per meter varied according to inoculant fungi and plant ages． There were some regressive interactions for colonization between the two fungi，as a general trend for ECM root colonization levels to increase with time at the expense of VAM colonization was observed during 16 weeks． The effect of phosphorus levels in soils on mycorrhizal formation was discussed．     

Water deficits are more important in delaying growth than in changing patterns of carbon allocation in Eucalyptus globulus

Potted cuttings of three Eucalyptus globulus Labill. clones (AR3, CN44, MP11) were either well watered or subjected to one of two soil water deficit regimes for six months in a greenhouse. Reductions in lateral branching, leaf production and leaf expansion were the leading contributors to the large differences observed in biomass production between well-watered and water-stressed plants. Although no significant differences among clones were observed in dry matter accumulation or in the magnitude of the response to soil water deficits, sensitivity of lateral branching, leaf initiation and whole-plant foliage to water stress was significantly lower in CN44 than in AR3 and MP11. When the confounding effect of differences in plant size resulting from the different watering regimes was removed, allometric analysis indicated that the genotypes differed in biomass allocation patterns. In addition to a drought-induced reduction in leaf number, water deficits also resulted in smaller leaves because leaf expansion was inhibited during dehydration events. Resumption of leaf expansion following stress relief occurred in all of the clones, but was particularly evident in severely stressed plants of Clone AR3, possibly as a result of the osmotic adjustment observed in this genotype.     

Leaf orientation,light interception and stomatal conductance of Eucalyptus globulus ssp. globulus leaves

Juvenile and adult leaves of the heteroblastic species Eucalyptus globulus Labill. ssp. globulus did not show active diurnal orientation toward or away from incident radiation. Juvenile leaves of a late-maturing sapling of a Tasmanian provenance were evenly distributed in all azimuth sectors. In contrast, an early-maturing sapling of the same age from Wilsons Promontory, Victoria had a predominance of adult leaf blades facing east and west. Mid-vein and blade angles of juvenile and adult leaves were non-random with an overall vertical declination of the leaves. Both leaf types intercepted a greater irradiance during the morning than at midday. Sub-horizontal juvenile leaves intercepted 22% more irradiance than vertical adult leaves during the middle of the day. The amphistomatal and isobilateral adult leaves intercepted sunlight equally on both leaf surfaces. Stomatal conductance was variable during the period of measurement but was similar for the Tasmanian juvenile (0.4 to 0.9 cm s(-1)) leaves and Wilsons Promontory adult (0.5 to 1.2 cm s(-1)) leaves. Greater light interception by the sub-horizontal juvenile leaves would confer a growth advantage to saplings and regenerating canopies. Reduced light interception and leaf temperature of vertical adult E. globulus leaves would assist in water conservation, particularly at high solar angles.     

蓝桉人工纯林土壤肥力研究

本项研究历时４年,研究结果显示,营造蓝桉纯林会引起林地土壤肥力明显降低,有机质、全Ｎ、有效Ｎ、Ｐ、Ｋ、交换性Ｃａ２＋、Ｍｇ２＋等７项指标均直接受影响。蓝桉人工林,经造林初期林地施肥能提高其生长量,但不能阻止林地土壤肥力下降。由于施肥促进了林木的生长,故也加强了对土壤肥力的消耗。     

蓝桉子代测定

本文对云南省一平浪蓝桉实生种子园的子代测定林进行初期评价。该子代测定采用α-循环设计,21个重复,每个重复有18个不完全区组,每个区组分为15个小区,每小区2株树。全部270个家系均为自由授粉的半同胞家系,按来源分为3个类型(原产地天然林、云南地方品种和种子园),11个地区。调查和分析的数据包括造林后2年时的树高、胸径、冠幅、干形、抗寒性和存活率等性状。分析结果如下:1. 不同的类型在生长表现上存在显著差异,来自种子园的类型为最好。2. 自不同地区的蓝桉在各性状上都表现出显著差异。在生长表现上,来自维克多利亚东部、西部和各种子园的子代比其它地区的好。云南当地蓝桉子代的耐寒性和两年时的保存率为最好,在生长、干形和抗病方面与塔斯马尼亚东部和南部的蓝桉子代表现相似。采用两株小区,明显比单株小区降低小区缺失率,提高分析的可靠性。表3参7。     

Distinct effects of auxin and light on adventitious root development in Eucalyptus saligna and Eucalyptus globulus

Adventitious rooting is essential for vegetative propagation of woody species. We studied the effects of auxin and light on the development of adventitious roots in cuttings obtained from seedlings of Eucalyptus saligna Smith and E. globulus Labill in an attempt to characterize the adventitious rooting process and identify factors controlling rhizogenesis. Root development was scored as rooting percentage, root density (roots per rooted cutting), mean rooting time and root length. In both species, rooting time was reduced in the presence of auxin. Cuttings from 2-month-old E. saligna seedlings were responsive to lower auxin concentrations than comparable cuttings from E. globulus seedlings. Cuttings from 3-month-old E. saligna seedlings rooted promptly and rooting was not significantly affected by light conditions. In contrast, rooting of cuttings from 3-month-old E. globulus seedlings exhibited recalcitrant behavior and no roots were formed if illuminated during the root formation phase. Effective root regeneration of E. globulus cuttings was obtained by a 4-day exposure to 10 mg l(-1) IBA and culture in darkness during the root formation step. Loss of rooting capacity with seedling age was more pronounced in E. globulus than in E. saligna. The possibility of switching adventitious rooting off and on by manipulating light regime and exogenous auxin supply in E. globulus, and the constitutive nature of rooting in E. saligna may provide useful models for examining the rooting process at the biochemical and molecular levels in Eucalyptus.     

Mycosphaerella species occurring on Eucalyptus globulus and Eucalyptus nitens plantations of Tasmania,Australia

The genus Mycosphaerella Johanson contains many pathogens capable of causing a severe impact on the growth of susceptible eucalypt species. The lack of knowledge about which species are present in Tasmania and their potential risk to the plantation industry prompted this study into the Mycosphaerella species occurring on Eucalyptus globulus and Eucalyptus nitens plantations in Tasmania. A total of 36 plantation and five road verge sites of E. globulus and E. nitens were sampled. Five Mycosphaerella species and three species from associated anamorph genera were isolated and identified in Tasmania; Mycosphaerella nubilosa, Mycosphaerella cryptica, Mycosphaerella tasmaniensis, Mycosphaerella grandis, Mycosphaerella vespa, Coniothyrium ovatum, Sonderhenia eucalypticola and Sonderhenia eucalyptorum. The most frequently isolated species with the highest incidence and severity of infection were M. cryptica and M. nubilosa. These two species appear to have the greatest potential to damage juvenile eucalypt plantations in Tasmania. A link between Mycosphaerella vespa and Coniothyrium ovatum is described for the first time.     

Heartwood and sapwood variation in Eucalyptus globulus Labill. trees at the end of rotation for pulp wood production

The amount of heartwood and sapwood in Eucalyptus globulus Labill. wood was determined in commercial pulpwood plantations at harvest age (12 to 15 years) in four ites in central portugal. twelve trees were sampled in each site at nine stem height levels. Heartwood was present in all the trees up to 82%–87% of the total tree height and amounted to 38%–41% of the total tree volume. The heartwood proportion in the stem cross-section decreased from the base upwards, representing 53.3% and 26.1% of the total area respectively at the base and 55% height level. The sapwood width remained relatively constant along the stem at a mean 38 mm up to the 55% height level. The trees within the site, the height level and their interaction were highly significant sources of variation for heartwood proportion and sapwood width. The heartwood diameter and sapwood width were positively correlated with radial tree growth.     

Physiology and anatomy of lenticel-like structures on leaves of Eucalyptus nitens and Eucalyptus globulus seedlings

Intumescences or abnormal, non-pathogenic, blister-like protuberant growths, form on Eucalyptus globulus Labill. and, to a much lesser extent, Eucalyptus nitens (Deane and Maiden) Maiden leaves when plants are grown in a high relative humidity environment. We examined the histology of intumescences and their effects on leaf photosynthetic processes. Intumescences were induced by placing E. globulus and E. nitens seedlings in a relative humidity of 80% in a greenhouse for 5 days. Symptomatic and asymptomatic leaves of plants with intumescence development were compared with leaves of control plants. Light-saturated carbon dioxide (CO(2)) assimilation (A(max)) and responses of CO(2) assimilation (A) to varying intercellular CO(2) partial pressure (C(i)) were measured. Symptomatic and asymptomatic leaf samples were fixed and sectioned and cellular structure was examined. Intumescences greatly reduced the photosynthetic capacity of E. globulus leaves and were associated with reduced electron transport rate and ribulose bisphosphate (RuBP) regeneration capacity. Tissue necrotization and cellular collapse of the palisade mesophyll and deposition of phenolic compounds in the affected areas, probably reduced light penetration to photosynthesizing cells as well as reducing the amount of photosynthesizing tissue. Photosynthetic capacity of E. nitens was unaffected. The intumescences resembled simple lenticels, both morphologically and developmentally. To our knowledge, this is the first time that lenticel-like structures developed in response to environmental conditions have been described on leaves.     

Advances in reproductive biology and seed production systems of Eucalyptus: the case of Eucalyptus globulus

Eucalyptus globulus is the main eucalypt species grown in Australian plantations. The focus on seedling deployment systems, coupled with exploitation of large, open-pollinated base populations for breeding purposes over the last two decades, has required a detailed understanding of the reproductive biology of this species. We review our research on the reproductive biology of E. globulus, with a focus on its breeding system and advances made in seed production systems. While most improved seed is still obtained from open-pollinated seedling or grafted seed orchards, the development of the one-stop/single-visit pollination procedure has revolutionised the breeding and deployment of this species. The reduced costs of controlled pollination has meant full pedigree-control can now be maintained in large advanced-generation breeding populations and E. globulus is one of the few eucalypt species where large-scale production of manually pollinated seed for family forestry is being undertaken.