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1.
C.-Y. Xie 《New Forests》2008,36(3):273-284
Ten-year data on growth and survival of two red alder provenance-progeny test trials located in the southern and northern coastal regions in British Columbia, Canada, were analysed and their implications for the genetic improvement of this species were discussed. A total of 42 and 41 provenances, each represented by two to five open-pollinated families were evaluated at each site, respectively. Results indicate that red alder provenances responded differently to the environmental conditions of the two sites. At age 10, red alder provenances tended to perform better at sites near their origin. The results support earlier work that two breeding zones should be delineated with the boundary at approximately 52° N. One may expect an average of about 5% decrease in stem volume and 6% increase in mortality, respectively, for each degree of southward and northward transfer of seed sources from their origins. Individual, family, and within-family heritabilities for height, diameter, stem volume were moderately high (0.22–0.42), for the southern zone, implying good potential for genetic improvement. Heritabilities were somewhat lower (0.12–0.39) for the northern zone because of greater environmental heterogeneity of the test site. Selecting the top 20 unrelated individuals for seed orchard establishment would result in 29% and 23% gain in stem volume at a rotation age of 40 years in the southern and northern zones, respectively. Correlation between ranks of the predicted breeding values for height at different ages and stem volume at age 10 increased rapidly when plantation was young and became relatively stable after 6 years of out-planting. Stem volume had much stronger correlation with diameter (≥0.84) than with height (≤0.67). Early selection at age 6 based on stem volume is therefore recommended.  相似文献   

2.
Twenty-four provenances of two species (Azadirachta siamensis and Azadirachta indica) have been introduced to China from South Asia, Southeast Asia and Africa Since 1995. This paper summarizes the researches on the introduction and planting of Azadirachta indica and analyzes the morphological, phenological characteristics, the growth rhythm, pollinating and seed yielding features of the intro- duced 24 provenances of the two species as well as the variations of filial generation plants. The experiments showed that most of the prove- nances of,4. indica have normal growth and can blossom and fruit in the dry-hot valleys with tropical climate conditions in Yunnan Province, China. The normal regions for A. indica were classified and the selection criteria for superior plants were put forward in this paper, more- over, the major contents of industry planning and technical approaches for A. indica plantation establishment were discussed and the countermeasures to reduce the neem-based pesticide products were also proposed.  相似文献   

3.
Realized genetic gains brought by the first-generation tree improvement of Acacia mangium were evaluated by analyzing the 1-year growth performance of growth (height, dbh) and form (stem straightness, multi-stem) traits using data collected from three second-generation orchards: groups B, C, and D. Each orchard was composed of improved families derived from open-pollinated seed of plus trees selected from the first-generation seed orchards and newly added unimproved families collected from the same geographic region. The number of improved families and that of the unimproved in each orchard were 31 and 23 for group B, 28 and 39 for group C, and 24 and 30 for group D. Gains were calculated as percentage increase of improved families over unimproved ones. Improved families performed better than unimproved ones in 11 out of 12 comparison cases: four traits each in the three orchards. Averages of the realized genetic gain across the three seedling seed orchards were 3.1%, 5.2%, 4.3%, and 0.5% for height, dbh, stem straightness, and multi-stem, respectively. Except for multi-stem, the performances of improved families were significantly better than those of unimproved families in all the three orchards for dbh and in two out of three orchards for height and stem straightness.  相似文献   

4.
Reproductive phenology was observed over three years in a Eucalyptus grandis seed orchard in Madagascar to determine the impact of geographic differences of parental selections on the expected genetic composition of seed crops. Pollen flow (observed pollen cloud) was deduced from a paternity assignment based on sampling from one year’s seed production. The two approaches were used to verify whether knowledge of phenology is sufficient to predict the genetic quality of the seeds collected. Despite the high flowering level, with a constant cycle over three years, the results demonstrated wide reproductive phenological differences associated with the parents’ origin, suggesting putative pollination disequilibrium. From both observed and expected pollen clouds, the results showed preferential mating among different provenances, which has consequences for seed crop composition. Phenological observations, which can be made inexpensively, can be used to promote methods of effective seed orchard management in order to improve the genetic quality of seeds.  相似文献   

5.
The optimum lifetime of Picea abies seed orchards in Sweden was calculated using a model which considers changes in seed yield over time, annual progress of genetic gain, establishment, management and seed costs, and both the monetary and genetic value of the seeds produced. The longer the seed orchard is active, the more genetically outdated the produced seeds will become, and thus their value will decline with time. A main scenario was constructed using the best available estimates for Swedish Norway spruce and was compared to various alternatives reflecting likely variations. The optimal lifetimes in all of these scenarios was in the order of 40 years. Sensitivity analyses showed that use of orchards for slightly more or less than their optimal lifetimes does not lead to large losses. A more effective tree breeding program could slightly reduce the optimal lifetimes. The optimal lifetime depends strongly on the relationship between monetary value and genetic gain. Thus, in cases where genetic progress is sufficiently rapid, the optimal lifetime may be less than 30 years.  相似文献   

6.
Seed was collected from two habitat types (harsh/rocky and favorable/control) within five Balkan provenances. An experiment was conducted to examine water uptake (grams water per gram of fresh seed) during 48 h after exposure to water. A second experiment investigated the effect of simulated-drought conditions (4% sucrose solution) compared to non-drought conditions (distilled water) on subsequent germination percentage. Seed from rocky habitats had less water uptake than those from control habitats for three of the provenances. However, water uptake was not correlated with subsequent germination. Drought simulation decreased germination but patterns for seed within each provenance were similar to germination under non-drought conditions. With the exception of one provenance, seed from the rocky habitats had lower germination than seed from control habitats. The data suggests some degree of adaptation to environmental conditions although variability was very high within each provenance’s habitat types. This is of particular importance when considering potential impacts of climate change and the anticipated migration of species due to changes in habitat.  相似文献   

7.
The magnitude and practical importance of family × site interactions for growth and form traits considered in radiata pine (Pinus radiata D.Don) breeding were analysed by four different methods: type B genetic correlation, regression coefficient, mean rank deviation and ecovalence. The material analysed consisted in growth, form and frost resistance assessments of 58 open pollinated half-sib families at 3 to 4 years old across three sites in Galicia (NW Spain). Analysis of variance revealed that family × site interactions were quantitatively important for all traits (diameter, volume, branch angle, straightness and frost resistance). The losses in potential genetic gain for a breeding population were important for all traits under individual selection but only for diameter and frost resistance under family selection. Omission of the ten most interactive families from the analysis considerably reduced the losses for all traits, although losses in potential genetic gain remained important for frost resistance under family selection. The results indicate that elimination of these families from breeding programmes would be an effective strategy for selecting for stability in performance across sites for all traits except frost resistance. In order to overcome this problem, selecting varieties for frost resistance specifically adapted to various regional contexts would be an option. However further studies under controlled conditions are required before making final decisions for radiata pine breeding programmes.  相似文献   

8.
Pinus patula and high-elevation (HE) sources of P. tecunumanii exhibit intermediate levels of resistance to pitch canker (Fusarium circinatum), compared to extremely resistant species such as P. oocarpa, and extremely susceptible species such as P. radiata. Seedlings from 20 P. patula provenances and 15 HE P. tecunumanii provenances were artificially inoculated with the pitch canker fungus at 21 and 12 weeks of age, respectively, and assessed for resistance 12–20 weeks later. There was important provenance variation in pitch canker resistance for both species. The 20-week LiveStem percentage ranged from 70.3% to 43.6% among the P. patula provenances and 59.6% to 11.7% among HE P. tecunumanii provenances. There was a geographic pattern to the provenance variation, and in both species, low altitude sources demonstrated more resistance than those from high elevation. Provenance variation in pitch canker resistance could be useful when making selection and breeding decisions with these species.  相似文献   

9.
The cotton whitefly, Bemisia tabaci (Genn.) (Hom., Aleyrodidae) is increasingly a very important pest on many vegetables, field crops and ornamental plants. Therefore, controlling of this pest is still needed especially under glasshouse conditions. The specialist whiteflies’ predator, Serangium parcesetosum Sicard (Col., Coccinellidae) appears to have a great potential for the cotton whitefly control. In this study, the dynamic changes in B. tabaci populations in glasshouse cabins in response to S. parcesetosum were monitored. B. tabaci were introduced to cotton plants in three cabins in average of 50 adults per plant. One and two weeks later, adult females and males of S. parcesetosum were introduced at a rate of one female and one male per plant in the first and second cabins, respectively. The third cabin was considered as a control. The results showed that the mean number of whiteflies in the control cabin was found significantly higher than that of either when S. parcesetosum was introduced 1 or 2 weeks after the infestation with the whitefly. Also, the mean number of B. tabaci was significantly higher when the predator was introduced 2 weeks rather than 1 week after B. tabaci infestation. The maximum mean weekly number of whiteflies/plant was 192.3 in the second week, whereas it was 294.6 in the third week and 1136.4 in the fifth week, in first, second and control cabins, respectively. In the last experimental week, the mean weekly numbers were 74.7, 122.9 and 684.7 whiteflies/plant in the three cabins, respectively. S. parcesetosum has been successfully fed, reproduced and established its population on B. tabaci on cotton plants. The mean weekly number of the predatory individuals increased gradually with the progress of the experimental time. The results demonstrated that the maximum reduction percentage in B. tabaci population was 90.7 and 86.5% in the fifth week after B. tabaci infestation, when the predator was introduced 1 and 2 weeks after the infestation with the whiteflies, respectively. Nevertheless, it is speculated that an earlier release of S. parcesetosum would be more effective in the biological control of B. tabaci.  相似文献   

10.
We evaluated the survival and growth of Abies homolepis and Picea jezoensis var. hondoensis seedlings on Mt. Ohdaigahara, where the population of sika deer (Cervus nippon) is high and an experimental fence has been in place for 13 years. No significant differences were detected in the survival of small seedlings between fenced and unfenced plots. The growth of A. homolepis was significantly higher in the fenced plot, but growth of P. jezoensis var. hondoensis did not show significant differences between fenced and unfenced plots. Seedlings of height ≤5 cm in the forest floor vegetation of the unfenced plot were probably too small for deer to find and browse, so they survived.  相似文献   

11.
General biology, seasonal flight numbers and ovipositional data were gathered to understand the phenology of the cherry bark tortrix, Enarmonia formosana Scopoli in Seattle, WA. Pheromone trapping during 2001 and 2002 showed a continuous flight period from May to September. During this time the greatest abundance of adults occurred during July and August. The combined seasonal egg data and larval developmental times indicate E. formosana is a univoltine species in the Pacific Northwest. Field releases of Trichogramma cacoeciae Marchal increased E. formosana egg parasitism on individual trees. During the two years, parasitism levels ranged from 72 to 74%.  相似文献   

12.
India is the largest grower of Eucalyptus with an area of 3.943 million hectares under plantations and E. tereticornis is the predominant species in the plains of southern India with an average productivity of 12–25 m3 ha−1 year−1. With the aim to establish seedling seed orchards of the species, seed lots of fifteen provenances were imported from Australia and a trial was laid. In the present study the genetic diversity existing in the seed orchard was estimated using ISSR–PCR. Seven ISSR primers amplified 663 amplicons in the size ranging from 255 to 2,711 bp. The total number of polymorphic bands varied from 59 to 123 with 100% polymorphic banding profiles. The average gene diversity (Hj) of all the provenances ranged from 0.0589 to 0.1109 and the total gene diversity estimated was low (H T = 0.130) when compared to the earlier reports from other eucalypts species. Analysis of Molecular Variance partitioned the ISSR variation into inter and intra population components. The inter population component accounted for 55.2% of the variation and the intra population component accounted for 46.3% (P < 0.001). A neighbour-joining analysis was done using the dissimilarity matrix to determine the aggregation of the individuals into clusters. Existence of population structure among the populations was revealed in STRUCTURE analysis but geographical region based clustering was not observed. The assessment of intra and inter genetic variation documented in the present study suggests that, along with the phenotypic traits, knowledge about genetic diversity measured at the DNA level in individuals of seed orchards provide an objective guide for selective culling of trees for maintaining optimal diversity for enhanced genetic gains.  相似文献   

13.
Liriodendron are ideal plants for research on mating system, systemic evolution and population genetics. Here we report the development and application of a set of simple sequence repeat (SSR) markers derived from expressed sequence tags (ESTs) of L. tulipifera. In total, 176 primer pairs were developed and yielded 132 EST-SSR markers that amplified clear SSR bands with genomic DNA of L. tulipifera. Transferability of these EST-SSR markers to related species and genera was further examined. Twelve highly informative loci screened from 132 EST-SSR markers were applied to explore the effective pollen dispersal patterns and male reproductive success of Liriodendron. A provenance trial population of Liriodendron comprised 12 L. chinense (Hemsl.) Sarg provenances and 5 L. tulipifera provenances. The four maternal trees were randomly sampled as tested maternal trees in the population. Paternities of 220 open-pollination progenies from 4 maternal trees above were potentially identified by means of paternity analysis, of which 138 progenies (accounting for 62.7%) were assigned to 49 male parents at the 95% confidence level. The cumulative exclusion probability of 12 EST-SSR loci was 98.5%. The average effective pollen dispersal distance of pollen donors ranged from 15 to 35 m, with the maximum dispersal distance of 77 m. There were obvious male reproductive success differences among individuals, ranging from 0 to 10.9%. The cumulative male reproductive success of individuals within 35 m radius around the known maternal trees reached 51.4%. Diversiform mating patterns, including selfing, intra-species mating and interspecies mating, coexisted in the occasion of open-pollination in Liriodendron.  相似文献   

14.
The genetic variation in seed weight, seed number per kg and seedling traits was compared among eight Acacia senegal provenances originating from the clay plain (east) and sand plains (west) of the gum belt in Sudan. The main objective of this study was to identify germplasm sources of A. senegal that have a good seed germination capacity and seedling traits suitable for reforestation in the clay-soil part of the dryland gum belt in the Blue Nile region in Sudan. A specific objective was to tentatively explore the adaptive strategy of A. senegal populations. Seventeen-week-old seedlings were planted in the field at spacing of 3 m × 3 m, giving 100 trees per plot and replication; within a randomized complete block design with four replications. The experimental site was in the clay plain region. Seed variables showed significant differences. Clay plain provenances showed considerable variation in seed weight and seed number. They had the smallest seed weight but the highest seed number, while the sand (western) provenances had the largest seed weight but lowest seed number. Seedling branch number, root length, root to shoot ratio and shoot dry weight differed significantly among the provenances 12 weeks after germination. Clay provenances had the highest branch number and shoot dry weight but the shortest roots and lowest root to shoot ratio. This was interpreted as showing better adaptation to the site in these local provenances in comparison to those originating from the western sandy soil regions. High positive correlations were observed between seedling variables, such as root nodule and branch numbers; this could be used for early selection. The variation was greater between provenance groups than within them, suggesting that especially selection among groups would yield genetic gain.  相似文献   

15.
The genetic variability of four natural populations of Larix gmelinii from East Siberia was determined and compared by RAPD analysis. Comparison of the RAPD profiles provided an estimation of variability in 193 RAPD fragments. More than 89% of these fragments were found to be polymorphic. The main genetic variability parameters of the two populations from Central Yakutia, a region free of fluoride pollution, had considerably higher values than those from East Transbaikalia, a region potentially affected by fluoride pollution (FLU, near a fluorite quarry growing on soils with a high natural content of fluorides). AMOVA revealed that 72.94% of the variation was within populations, while only 7.05% of the variation was between populations within geographical regions. The genetic diversity of the FLU fluoride-tolerant population was the lowest, but only slightly lower than that of a fluoride non-tolerant population from Chita, 50 km distant from FLU. Although this study demonstrates the absence of fundamental alterations of genetic structure within the populations of L. gmelinii growing on soils with a high content of fluorides, it is presumed that the reduction of genetic diversity was the genetic response of the FLU population to such an environmental stress as a constantly high concentration of fluorides within the soil.  相似文献   

16.
Interspecific protoplast fusion between two monokaryotic strains (a methionine auxotrophic and chloramphenicol-resistant Pleurotus ostreatus strain and a wild-type strain of Pleurotus pulmonarius) was carried out to introduce mitochondrial DNA (mtDNA) from P. ostreatus into P. pulmonarius. Because mycelial colonies regenerated on minimum medium containing chloramphenicol only after the treatment of protoplast electrofusion, the regenerants were regarded as protoplast fusants. The fusants isolated from regenerated colonies were uninucleate, and their resistance of chloramphenicol seemed to be a stable trait. The fusants mated with P. pulmonarius but not with P. ostreatus, and showed almost identical random amplified polymorphic DNA (RAPD) patterns to that of the parental P. pulmonarius monokaryon. The sizes of mitochondrial genomes were estimated to be 81.5 kb for P. ostreatus monokaryon, 54.9 kb for P. pulmonarius monokaryon, and 84.5 or 86.0 kb for the fusants. BamHI and EcoRI digest patterns of the fusant mtDNAs were almost the same as the parental P. ostreatus monokaryon. From the above results, the fusants seemed to carry nuclei derived from the monokaryon of P. pulmonarius and mtDNA including the chloramphenicol-resistance gene from the P. ostreatus monokaryon, suggesting that the P. ostreatus mtDNA had been introduced into P. pulmonarius cells by interspecific protoplast fusion. Contribution No. 383 of the Tottori Mycological Institute  相似文献   

17.
In the last 10 years, four species of psyllid were detected in Brazil on eucalypts: Ctenarytaina spatulata in 1994, Blastopsylla occidentalis in 1997, Ctenarytaina eucalypti in 1998 and Glycaspis brimblecombei in 2003. The latter two are serious pests in several countries. In Brazil, G. brimblecombei caused significant damage to the eucalypt plantations in the first years of its introduction. Now this pest is under control due to the programmes of integrated pest management, where the parasitoid is the principal control agent. The four eucalypt psyllid species introduced into Brazil are presented with information on distribution, hosts, biology and control.  相似文献   

18.
Plantations of Pinus spp. constitute approximately 50% of the South African forestry industry. The first aim of this study was to develop a reliable inoculation technique to screen Pinus spp., for tolerance to infection by F. circinatum, which threatens pine forestry in South Africa. Inoculation of branches was compared with stem inoculations and we considered the number of branches or trees required to obtain statistically significant results. Furthermore, variation in the susceptibility of some Pinus families, clones and hybrids was considered. Results showed that branch inoculations were closely correlated with those from stem inoculations, and that it is important to consider branch and stem diameters when assessing susceptibility of trees. Subsequent trials using branch inoculations showed significant differences in F. circinatum tolerance amongst a range of pine species and hybrids of potential interest to forestry in South Africa. Significant differences in susceptibility were also found among clones of two P. radiata families. The most tolerant trees were P. elliottii × caribaea and P. patula × oocarpa hybrids, while the most susceptible species were P. patula, P. greggii and hybrids of these two. This is the first trial considering the susceptibility of Pinus hybrids, Pinus clones and some P. patula provenances, and the results indicate excellent potential for breeding for tolerance to pitch canker in South Africa. Application The accurate selection of disease tolerant planting stock for the South African forestry industry is crucially important for the continued sustainability of this important industry. The work described here provides valuable information on an artificial inoculation technique that will assist the industry in screening trees for tolerance to the pitch canker fungus, F. circinatum. It also provides some indication of the relative susceptibility of a number of Pinus spp., hybrids and families currently being evaluated in the country.  相似文献   

19.
Cotton bollworm, Helicoverpa armigera Hubner selected for five generations with Bacillus thuringiensis insecticidal crystal protein Cry1Ac in the laboratory developed 12.98-fold resistance. Resistance and susceptible populations were mass crossed to study the dominance of resistance. The Cry1Ac—selected (BCR) population showed 5.8-fold resistance to Cry1Aa and 5.04-fold resistance to Cry1Ab. The degree of dominance (D) was 0.34 and 0.40 for the R × S and S × R hybrids, respectively, which indicates incomplete recessive character of Cry1Ac resistance in the population. The estimated realized heritability (h 2) and response quotient (Q) of resistance for Cry1Ac were 0.52 and 0.15, respectively. This indicated the lower phenotypic variation in the selected population. The resistance risk assessment based on h 2 indicated that the resistance would increased tenfold after <9 generations for Cry1Ac in the resistant population. The results show the ability of H. armigera to develop resistance against Cry1Ac and cross-resistance to Cry1Aa and Cry1Ab.  相似文献   

20.
利用扫描电镜观察了忍冬(Lonicera jàponica Thunb)和华南忍冬(Lonicera confus)叶表皮形态特征,观察指标包括:气孔器、表皮毛、表皮细胞等.结果表明:气孔仅分布在下表皮,气孔器呈无规则型散生;上表皮细胞的垂周壁呈沟槽状下陷;下表皮密被表皮毛(包括腺状毛和非腺毛),同时还分布有瘤状的草酸钙簇晶.为进一步证明这种瘤状结构是否为草酸钙簇晶,作者发现利用Fluo-3/AM(钙离子荧光指示剂)处理的活体叶片在激光共聚焦显微镜下能够发出强烈的荧光.此外,通过电子探针对瘤状物进行分析,发现其元素组成为C、O、Ca.上述叶表皮构造特征,有利于减少植物体水分散失,还有助于植物适应富钙的石灰土,从而适应我国西南岩溶区特殊的干旱、富钙的环境.电镜观察结果表明,在忍冬叶上表皮中脉处有呈线状分布的腺状表皮毛,而华南忍冬叶上表皮则无表皮毛分布,这一微形态特征可以作为二者种间特异性差别,从而为二者的合理区分提供一定的依据.  相似文献   

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