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1.
Shy seed production in orchards of Eucalyptus nitens is a major barrier to the deployment of genetic gain in South African plantations. A machine learning method was used to identify optimal sites for the establishment of E. nitens seed orchards within the plantation forestry landscape of the summer rainfall region of South Africa. The ensemble classifier random forests (RF) was used to identify the environmental factors conducive to E. nitens floral bud production, and, based on these, build a predictive model deployable to the plantation forestry landscape for identifying suitable areas for E. nitens seed orchards. The RF model predicted site suitability likelihood for floral bud production with a high level of accuracy (area under the receiver operating characteristic curve = 0.83). Within the climatically optimal range for growing E. nitens, flower bud production was more abundant and consistent on cold slopes, i.e. sites experiencing lower minimum air temperatures during spring and autumn. The model was applied to the commercial plantation forestry landscape for the purpose of indicating sites climatically optimal for floral bud production in E. nitens and the establishment of breeding and seed production orchards of the same species. 相似文献
2.
Winter chilling is a key environmental trigger of floral induction in temperate Eucalyptus. Over the past two decades, considerable site × eucalypt flowering interaction research has been undertaken over a range of high elevation (>1 100?m asl) forestry sites in the South African summer rainfall area. A practical method of accurately monitoring eucalypt bud temperature at remote sites in these areas was needed for this research. Utilisation of traditional methods of air and bud temperature measurement were not viable, due to significant risks of data and meteorological equipment loss posed by severe weather, vandalism and theft. Between 1996 and 2004, a robust structure for housing the miniature Hobo® temperature logger (hereafter termed ‘Hobo pole’) was designed and utilised for in-field monitoring of air temperature in the research trials. During 2009 and 2010, an experiment was conducted to investigate the relationship between E. nitens bud temperature (BudT), Hobo pole air temperature (HoboAT) and radiation screen air temperature (ScrnAT), and develop appropriate calibration models. Attempts to develop a single model for predicting hourly BudT from hourly HoboAT over the entire annual period yielded unsatisfactory results (maximum R?2 value 0.49). Separate winter and summer regression models were subsequently developed for predicting BudT from HoboAT, ScrnAT from HoboAT, and BudT from ScrnAT. In these regressions, R?2 values were generally slightly higher, and SE values lower, for mid-winter data than for mid-summer data. In mid-winter, BudT on HoboAT gave the highest R?2 value (0.99) and lowest SE value (0.49 °C) of all regressions. The Hobo logger/Hobo pole combination, together with developed regression models (presented in this paper), offers one practical, cost-effective solution for accurately monitoring eucalypt bud temperature at remote, high-elevation forestry sites in South Africa. 相似文献
3.
Intraspecific and interspecific controlled pollinations wereattempted on 12 E. nitens trees representing a range of provenances.Over consecutive flowering seasons there were consistent differencesin the relative flowering times of five genotypes on one site.Of 24 intraspecific combinations attempted in 1985 62 per centset seed, and overall 45 per cent of flowers pollinated setseed. All but one of 10 interspecific combinations succeededwith 33 per cent of flowers pollinated setting seed. The maternalinfluence was generally stronger than the paternal, in termsof number of seed set and seed weight. For all mothers, themean number of seeds per capsule from self-pollinated and open-pollinatedflowers were only 2.2 and 3.8, compared with 6.8 and 7.9 forflowers hand-pollinated with E. gunnii and E. nitens pollenrespectively. Implications of various aspects of the reproductivebiology of these species on breeding programmes are discussed.Two previously identified forms of E. nitens showed consistentdifferences in floral morphology, flowering time and seed maturity.Their taxonomic status is commented on. 相似文献
4.
Gene flow between introduced and native Eucalyptus species 总被引：2，自引：0，他引：2
Barbour Robert C. Potts Brad M. Vaillancourt René E. Tibbits Wayne N. Wiltshire Robert J.E. 《New Forests》2002,23(3):177-191
The first evidence of in situ F1 hybridisation between an introduced eucalypt plantation species, Eucalyptus nitens, and a native eucalypt species is presented. Open-pollinated seed was collected from a mature E. nitens trial and from the adjacent native species, E. ovata and E. viminalis on the island of Tasmania. Nearly 70 000 seedlings were grown to a size at which hybrids could be clearly distinguished from pure species seedlings on the basis of morphology and a nearly species-specific isozyme allele. Hybridisation was observed between E. nitens and E. ovata, but no hybrids involving E. viminalis were found. This pattern of hybridisation was consistent with the flowering time overlap between the E. ovata and E. nitens. Eucalyptus nitens progenies displayed a low and relatively homogeneous level of hybridisation, averaging 0.15% per tree. In comparison, the proportion of hybrids obtained from the adjacent E. ovata trees varied from 0.04 to 16% per tree. Whether progeny arising from such hybridisation will survive and grow in nature to allow for backcrossing and introgression of the exotic genes into the native population is not yet known. 相似文献
5.
《Southern Forests》2013,75(4):267-271
The aim of this study was to compare survival rates and leaf gas exchange of micro- and macro-propagated Eucalyptus grandis × E. nitens, and seed-propagated E. grandis and E. nitens, at a site in Hilton, KwaZulu-Natal, South Africa, where the conditions were suitable for cold-tolerant hybrid eucalypts. Fourteen months after planting, 50% of micropropagated E. grandis × E. nitens had survived, compared with 87% for macropropagated E. grandis × E. nitens, 53% for seed-propagated E. grandis and 93% for E. nitens. Differences in instantaneous leaf gas exchange and parameters derived from the light and CO2responses of gas exchange were not significant between micro- and macro-propagated plants, but were significant between species. All trees used water more efficiently during photosynthesis at 16 months (winter; June 2004) than at 14 months (autumn; April 2004) after planting. However, micropropagation yielded plants that were most vulnerable to the combination of prolonged dry conditions and air frost 相似文献
6.
《Southern Forests》2013,75(4):319-328
Harvested logs supplied from five fibre-managed Eucalyptus nitens plantation coupes with different growing environments were assessed for quality and stiffness. Billets extracted from the logs were rotary peeled for veneer. When averaged across the five coupes, 30% of veneer recovered could be used directly in structural plywood production and an additional 20–25% could be used after further processing. In visual assessment most veneer was assigned an Australian/New Zealand Standard AS/NZS2269.0:2012 Quality D. Acoustic testing during processing showed veneer peeled from a drier and lower elevation coupe had significantly higher dynamic MOE values than veneer processed from logs harvested from wetter higher elevation coupes. To examine the utility of the E. nitens peeled veneer in the production of structural plywood, it was combined with veneer of a known higher stiffness, rotary peeled from regrowth forest Tasmanian oak species logs. Structural seven-ply panels were manufactured from the veneer prepared in three different ply arrangements. Mechanical testing of the panels in accordance with AS/NZS2269.0:2012 showed that an F17 target stress-grade panel product of 83% E. nitens and 17% Tasmanian oak species could be produced, if E. nitens veneer of higher stiffness were selected from veneer segregated by estimated dynamic Modulus of Elasticity value. Panels with 50% E. nitens and 50% Tasmanian oak veneer could be produced by selecting E. nitens veneer of lower stiffness after segregation. In the majority of panels tested stress-grade rating was limited by perpendicular bending strength. Outcomes from the study indicate that structural plywood can be manufactured using differing proportions of E. nitens veneer, rotary peeled from fibre-managed plantations, provided it can be segregated into stiffness categories and selected to achieve a target stress-grade. 相似文献
7.
Eucalyptus nitens (Deane & Maiden) Maiden takes at least five years to initiate flower buds from seed and is an infrequent and light flowerer. Because this behavior constitutes a major impediment to breeding programs, we examined the mechanisms controlling floral induction in E. nitens, with the long-term aim of reducing generation time and increasing seed yield. Application of paclobutrazol reduced the concentration of endogenous gibberellic acid (GA) in apical tissue and enhanced the reproductive activity of grafted trees maintained outside over winter in Canberra, Australia. Grafts maintained in a warm greenhouse over winter did not produce flower buds, despite the paclobutrazol-induced reduction in GA concentration of the apical tissue. Exposing untreated grafts, which had been maintained over winter in a warm greenhouse, to low temperature the following spring reduced growth but did not induce flower bud production. Addition of GA(3) to paclobutrazol-treated grafts reduced the effect of paclobutrazol on reproductive activity. 相似文献
8.
The number of fertile and infertile scales, filled and empty seeds, cone volume, seed efficiency and the incidence of insect and disease damage to seed were evaluated for seven jack pine (Pinus banksiana Lamb) and six black spruce (Picea mariana [Mill.] B.S.P.) seedling seed orchards in northern Ontario, Canada. On average, the seed potential of jack pine and black spruce cones was 50 and 82 seeds, respectively. Cone volume and the number of fertile scales were under strong genetic control and well correlated with one another for both species. Seed efficiency values were high for jack pine (60%) but poor for black spruce (24%). The incidence of seed insect damage was less than 2.5% for both species and nil for seed diseases. 相似文献
9.
The degree to which freezer storage fulfilled the chilling requirement of ponderosa pine (Pinus ponderosa Dougl. ex Laws.) seedlings of two sources was determined by monitoring their development after potting or planting. The seedlings were lifted in September, October, November, or March and subjected to storage before outplanting. The fulfillment of chilling was assessed by measuring days to budbreak, cumulative percentage of seedlings flushing, foliated shoot length, and rate of bud abortion. The effect of freezer storage depended on stage of seedling development at lifting, length of storage, and seed source. Storage did not totally replace winter conditions, especially for seedlings lifted in September and October. Those from a high-elevation seed source flushed sooner than those from a low-elevation source. Delayed budbreak after planting of early lifted seedlings from the high-elevation source disappeared in the second year, but those from the low-elevation source continued to show effects. Seedlings lifted and stored in November had patterns of budbreak that were similar to those of seedlings that had overwintered in beds. 相似文献
10.
《Southern Forests》2013,75(2):145-154
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. 相似文献
11.
To evaluate the practical application of an indoor seed orchard, we compared the seed production, final germination rates
and mating patterns of potted Cryptomeria japonica D. Don clones in two miniature seed orchards: one in a glasshouse and the other outdoors. There was no statistically significant
difference in total seed production between the orchards (P = 0.275, ANOVA). However, the final germination rate of seeds produced in the indoor orchard was significantly lower than
that of seeds produced in the outdoor orchard (P < 0.01, Wilcoxon test). The average self-fertilization rate was higher in the indoor orchard (27.2%) than in the outdoor
orchard (5.6%), and this parameter was strongly associated with the reduced final germination rates of the seeds harvested
in the glasshouse. Pollen contamination was considerably lower in the indoor seed orchard (48.9% in the outdoor seed orchard
and 4.4% in the indoor seed orchard). χ2 tests indicated that the paternal contributions of each constituent clone differed significantly in both orchards (P < 0.001 in both cases). The strong variations in paternal contributions among indoor orchard clones was significantly correlated
with their respective pollen production capacities (Spearman ρ = 0.693, P < 0.001). To reduce the high self-fertilization rates, we recommend the use of orchard clones with similar pollen production
capacity in indoor seed orchards. 相似文献
12.
Miyoko Tsubomura Eitaro Fukatsu Ryogo Nakada Yoko Fukuda 《Annals of Forest Science》2012,69(8):867-875
Context
Clonal variation of flower production has been investigated thoroughly in coniferous tree species because of the importance of flowering in seed production from seed orchards. However, the inheritance of flower production by progeny test has not been previously studied well, so the heritability of male flower production of Cryptomeria japonica, the most important species for forestry and the main cause of pollinosis in Japan, was estimated to provide fundamental data for pollen control in seed orchards and plantation forests.Methods
Male flower production in C. japonica was investigated for three years using 20 full-sib families created by a diallel mating design with six parents using gibberellin treatment to promote flowering.Results
The narrow-sense individual tree heritability of male flower production in each year was estimated as ranging from 0.777?±?0.339 to 1.050?±?0.346 by sib analyses. The contribution of general combining ability to the total variance varied from 24.1 to 35.6?%. The highest contribution of specific combining ability was 1.42?%. By selecting the top 50?% of parental clones for reduced male flower production, the genetic gain in lowering male flower productivity was predicted as 46.1?C53.0?%.Conclusion
Our results suggest that male flower production in C. japonica is under strong genetic control and that control of male flowering by breeding is possible with a well-designed program. 相似文献13.
Within-tree variation in fibre length and coarseness was studied in fifty trees of E. globulus and E. nitens to develop a non-destructive sampling strategy. Trees, aged 5 to 9 years, were sampled across a range of sites in southern
Australia. Simulated core samples were removed at six fixed heights easily accessible from the ground (0.5, 0.7, ... 1.5 m)
and at eight percentage heights (0, 10, 20, ... 70%). Whole-tree values, calculated from percentage height data, were correlated
with the core data to determine the optimal sampling height. Core samples were found to be reliable predictors of whole-tree
fibre length, but results were variable for fibre coarseness. Simulated cores taken from the recommended sampling heights
explained 87% and 71% of variation in whole-tree fibre length for E. globulus and E. nitens respectively and 54% and 45% of the variation in whole-tree fibre coarseness. Fibre length at all fixed heights showed good
correlations with whole-tree values at all sites for E. globulus. For E. nitens the correlations were slightly lower and variable across sites. Results for fibre coarseness varied across sampling heights
and sites for both species. The recommended sampling height for fibre length is 1.5 m for both species, whilst for fibre coarseness,
the recommended sampling heights are 0.9 and 1.1 m for E. globulus, and 0.9 and 1.3 m for E. nitens. Radial orientation of cores was not important and neither fibre length nor coarseness were related to tree size or basic
density. To estimate stand mean fibre length to an accuracy of ±5% would require sampling 9 whole trees or taking cores from
13 trees for E. globulus and 4 whole trees or cores from 8 trees for E. nitens. For estimating stand mean fibre coarseness, 10 whole trees of E. globulus and 7 whole trees are needed for E. nitens. Core sampling for stand mean coarseness would require more trees: 13 to 21 for E. globulus and 11 to 16 trees for E. nitens.
Received 17 September 1998 相似文献
14.
Until recently, the most important factors affecting the economics and genetics of the seed crop from seed orchards were considered to be the timing and duration of flowering, variation in fertility and the total number of clones used to establish the seed orchards. Change in climatic conditions however is an emerging factor that could prove crucial regarding the timing of flowering and synchronization among clones and thus, the quality and quantity of seed production. The temporal and spatial variation in flowering phenology and the duration of flowering were studied in consecutive years in a Pinus nigra Arn. seed orchard. Sixty plus trees representing the distribution of the species in Northern Greece were used to establish the seed orchard, and nineteen ramets per clone were planted in a honeycomb experimental design in order to avoid kinship. Temporal variation among clones, as well as spatial variation among ramets within clones growing at different sites of the orchard were recorded, for initiation and duration of male and female flowering. The majority of clones were synchronized in dates of flowering during the year with weather conditions close to the long-term climatic conditions, except for a limited number of clones that were precocious or late flowering. The pronounced variability in climatic conditions over the 2 years strongly affected the flowering and synchronization among clones, resulting in almost complete asynchrony during the xerothermic year, which was characterized by a prolonged mean monthly temperature increase of 2.3 °C and a water deficit of 53% in a 7-month-period (November to May). These results suggest that one of the effects of a warmer and drier climate may be the lack of flowering synchronization, as pollen shedding might be completed before female conelets reach the phase of receptivity. The restriction of male parentage to a limited number of clones severely violates the panmixia assumption and could result in fertilization failure. The projected climate change for the Mediterranean region could potentially prove detrimental for fertility and flowering synchronization of forest trees, having consequences on the quantity and genetic diversity of the seed crop in seed orchards, and the natural regeneration of forest trees in forest ecosystems due to the reduced percentage of sound seed. 相似文献
15.
试论世界桉树栽培现状和我国桉树人工林发展策略 总被引：4，自引：0，他引：4
桉树是世界上热带、亚热带地区最重要的人工林树种之一,其面积已超过600万ha。文中着重介绍了巴西发展按树的经验,并提出了我国应采取的对策。 相似文献
16.
[目的]为了解灰木莲引种到广西凭祥地区花期物侯及生殖构件分布状况,为其在引种地败育机制的研究奠定基础。[方法]选择中国林科院热林中心树木园、白云实验场、伏波实验场的灰木莲人工林为观测对象,参考Dafni方法,从林分到单株水平调查研究灰木莲在广西凭祥地区的花期物候、开花特征及生殖构件分布,跟踪观察单花开花动态进程,统计花部组件大小、数量及位置等特征。[结果]表明:灰木莲花为子房上位的两性花,雄蕊群着生于雌蕊群下部,雄蕊短小,其高度仅达到雌蕊群下缘;灰木莲花芽到开花过程可分为混合芽阶段、花芽阶段、花蕾露白阶段、白蕾阶段、展花阶段、花瓣脱落阶段6个阶段,花被片展开存在二次开合现象;在适生区,灰木莲开花特征稳定,开花强度中等,不同海拔高度灰木莲林分的花期物侯存在差异,林分的生殖构件在林内、林缘分布差异显著,且生殖构件的败育率极高。[结论]灰木莲引种到广西凭祥地区花期物侯稳定,开花同步性较高,但是花果转化率极低。 相似文献
17.
The effective number of clones (N
c) wasestimated for 255 conifer clonal seed orchards in Finland, Korea, andSweden, based on the variation in the number of ramets among clones. Themean census number of clones (N) varied from 70, in 13 KoreanPinus koraiensis seed orchards, to 139 in 176 Finnish Pinussylvestris seed orchards. The mean effective number of clones(N
c) was 66, with a range from 10 to 421. One fifthof the orchards had N
c between 10 and 40, and twothirds between 41 and 160. On average, the relative effective number ofclones (N
r =N
c/N) was 0.74, with a range from 0.2to almost 1.0. Thus, the census number of clones in a seed orchard isgenerally rather informative, but the effective number of clones is moreinformative. Many of these first-generation seed orchards wereestablished with an intention to have near-equal numbers of ramets foreach clone. The use of effective number of clones may be more importantin future seed orchards and genetically thinned seed orchards. 相似文献
18.
The seasonal growth (height and diameter) of 12 Eucalyptus species (E. agglomerata, E. baxteri, E. botryoides, E. cladocalyx, E. globoidea, E. microcorys, E. muelleriana, E. nitens, E. obliqua, E. pilularis, E. regnans, E. saligna) was measured on trees between 2 and 4 years of age on four hill country microsites; upper shady, lower shady, upper sunny
and lower sunny slopes. Additionally, seasonal mean daily solar radiation and temperature were recorded on each aspect over
the same time period. Height and diameter growth were both strongly seasonal; mean diameter growth was highest in the spring
(0.91 cm) while height growth was greatest in the summer (0.57 m). Conversely, diameter and height growth were least in the
winter (0.38 cm and 0.09 m respectively). There was a significant interaction between season and aspect for height (P = 0.01) and diameter (P = 0.02). Diameter and height growth on the shady face was similar to that on the sunny slopes during summer, but, in winter
growth on the shady face was typically lower than the sunny. Slope position also influenced height growth (P = 0.001), particularly in the winter, growth on the lower slope being less than on the upper. There was a strong linear relationship
between seasonal height growth and solar radiation but a curvilinear relationship between seasonal diameter growth and radiation.
Consideration of the influence of topography on solar radiation and other environmental factors may allow more reliable assessment
of potential forest production on a micro scale. 相似文献
19.
Loblolly pine seed dormancy: constraints to germination. 总被引：1，自引：0，他引：1
Stratification by moist chilling is often used to break seed dormancy in loblolly pine (Pinus taeda L.). The role that moist chilling plays at the cellular level in preparing the embryo for germination and early seedling growth was investigated. Moist chilling did not affect the embryo's ability to mobilize seed storage proteins, which is a biochemical marker of early seedling growth. Analysis of in vivo protein synthesis profiles indicated that moist chilling has only a subtle effect on gene expression in the embryo or germinant. The means by which moist chilling affects interactions between the seed coat and the living tissues of the seed also was studied. Although the seed coat is mainly a mechanical barrier to germination, seed coat replacement studies showed that moist chilling alleviates some factor(s) in the seed coat that significantly inhibit germination. 相似文献
20.
《Scandinavian Journal of Forest Research》2012,27(1-4):513-520
The proportion of background pollen grains in the seed crops of two Pinus sylvestris seed orchards in Central Finland was estimated with the aid of multilocus allozyme markers. The orchards studied were more than 30 years old and in full pollen production. For the bulked seed crops of the seed orchard with southern clones the estimated average of background pollination over four years was 26%. There were statistically significant differences between years. No significant heterogeneity in the degree of background pollination between clones was found. Among single ramets there was significant heterogeneity in the estimated contamination rates, but the variation was not related to position in the orchard. For the seed orchard with northern clones the bulked seed crop was studied only for one year and the level of background pollination was found to be 33 %. These estimates are fairly high, but lower than for many other orchards. Background pollination at this level will cause losses in expected genetic gains. Part of the seeds from northern orchards will not be adapted to the intended area of use. 相似文献