Ahmed M. Abd-El Dayem
Forestry Department, Horticultural Research Institute, Agricultural Research Center, Giza, Egypt
From 1990 to 1992 field surveys of poplar stand trees were conducted to select the mother trees of different poplar species for reproduction. For Populus alba, the mother tree was located at Sakha (Kafer El-Sheikh) as well as at El-Behera; for P. nigra the mother tree was located at Gharbia; for P. deltoides, male and female, and P. euramericana, the mother trees were located at Giza (H.R.I. farm). Stoolbeds were grown in the forest nursery from the different Populus species in February 1992. Stem cuttings obtained from the mother trees were used, with the exception of P. deltoides, which was propagated from stem cuttings for both the male and female trees as well as the sexual reproductive seedlings which were selected from germinated seeds during 1990 to 1992. Stem cuttings from stoolbeds were then taken during February of the two successive seasons, 1996 and 1997, and rooted in a mixture of 1:1 peat moss and clear sand by volume of 25 cm diameter in plastic pots. Every 21 pots represented one genotype and every pot contained two stem cuttings. At the beginning of August in the two seasons, the seedlings were lifted and the following data were recorded: percentage of plant survivals, plant height (cm), number of developed leaves, mean leaf area (cm2 ), number of adventitious roots, and length of the longest root (cm). Also, polyacrylamide gel electrophoresis separation of total soluble proteins in leaves of each genotype was investigated. The results obtained indicated that among all studied genotypes, P. nigra was the best for vegetative reproduction, followed by P. euramericana (1); moreover, the hybrid P. deltoides exceeded their parental species (P. deltoides male and female) in this respect. On the other hand, P. alba proved to be difficult for vegetative propagation since more than 80% of the cuttings failed to grow and survive in both studied seasons. All poplar species under investigation showed significant differences in their vegetative characters, which means that vegetative growth of poplar seedlings was significantly affected by species. Data also revealed that polyacrylamide gel electrophoresis separation of total soluble proteins can be used as a genetic fingerprint for identification, differentiation, and comparison among the different species of Populus under investigation.
Inger Åhman
Svalöf Weibull AB, SE-268 81 Svalöf, Sweden
Defoliating leaf beetles, mainly of the species Phratora vulgatissima and Galerucella lineola, are among the most important insect pests in the biomass willow crop in Europe. Beetle-susceptible willow varieties of the species Salix viminalis and hybrids between S. viminalis and Salix schwerinii dominate in the plantations at present. Varieties of the generally more beetle-resistant species Salix dasyclados (Salix burjatica) are less common. Since 1987, breeding to produce willow varieties suitable for biomass production has taken place at Svalöf Weibull AB in Sweden. The main breeding goals have been increased yield level and improved yield stability through breeding for resistance to Melampsora rust and tolerance to frost. Breeding for resistance to shoot-tip infesting insects such as the cecidomyid Dasineura ingeris and various lepidopteran species has also been included in the program, as a way of reducing problems with side-shoots at cutting production. Plant selections were based on field screenings. However, P. vulgatissima and G. lineola have been rare in plantations and there were no opportunities for selection of beetle-resistant clones up to 1997. Since then, beetles have been abundant at some experimental sites, and advanced breeding lines as well as clones potentially useful as resistance sources have been scored for leaf damage there. Plantations of potentially beetle-resistant clones include the North American species Salix eriocephala and the eastern European species S. dasyclados and hybrids between these and other species. It is evident that certain S. dasyclados types are very resistant and promising for breeding, whereas the S. eriocephala material studied has a lower potential as a resistance source.
Nuria Alba, Dolores Agundez, and Ricardo Alía.
Departamento de Mejora Genética y Biotecnología, CIFOR-INIA,
Apdo 8111, 28080 Madrid, Spain
F-statistics were employed to analyse quantitative and isozyme variation among 14 families collected from seven native populations of Populus alba L. in Spain. Seven polymorphic isozyme loci that tested neutral were used to provide an empirical basis for constructing a null hypothesis to test natural selection as a determinant of quantitative evolution in phenotypic traits: growth variables, stem form, wood density, and survival. The average Fst value in isozymes loci (0.245) was compared with that obtained for phenotypic traits. Results show a strong influence of random effects on the pattern of variation of the species measured by isozyme loci. The importance of selection and random effect in the pattern of variation of quantitative traits is discussed to establish optimal sampling strategies of genetic diversity for use in genetic resource conservation of the species.
G. Allegro1 and S. Augustin2
1Istituto di Sperimentazione per la Pioppicoltura, Casale Monferrato, Italy
2NRA-Station de Zoologie Forestiére, Ardon, France
This report illustrates the contributions of European research on poplar resistance to insect pests in the period 1992-1999. Twenty-five papers were reviewed, dealing with genetic resistance (assessment of plant resistance behaviour and poplar resistance mechanisms), evaluation of resistance in genetically engineered poplars, and environmentally induced resistance. During the reported period, European research on poplar resistance to insect pests was almost completely sustained by France and Italy, probably on account of the high economical importance of poplar cultivation in these countries, but also because of the increasing public perception towards the problems of environmental pollution and human safety. Some outcomes are highly interesting. The development of screening techniques to characterise plant-aggressor interactions allowed the assessment of poplar clonal resistance to Hyphantria cunea and Phloeomyzus passerinii in Italy and to Chrysomela tremulae and Chrysomela populi in France. Moreover, the discovery of the role of phenolic glycosides in the resistance behaviour of poplars towards key pests like C. tremulae and C. populi or Ph. passerinii, as well as of a genomic region in Populus trichocarpa involved in resistance to C. tremulae, could represent a first step towards a marker-assisted selection for resistance to insects. Noticeable results were recorded from studies on genome manipulation techniques, which led to the production of genetically engineered poplars modified by the insertion of genes encoding proteinase inhibitors or Bacillus thuringiensis endotoxin. This success shows new exciting perspectives in pest control, provided that European policies define clear strategies on deployment of transgenic trees.
A. Álvarez1 , M.T. Cervera2, D. Agúndez, N. Alba1 , J.M. Zapater2 , and J.M Grau2
1 Centro de Investigación Forestal, INIA, Madrid, Spain
2Centro Nacional de Biotecnología, Madrid, Spain
AFLP (Amplified Fragments Length Polymorphism) has been chosen as the most suitable molecular marker for clonal identification. AFLP is a dominant marker that covers a wide range of the genome obtaining a great number of polymorphisms and making it possible to identify individuals and try to detect specific polymorphisms between clones that show similar morphological characters and similar behaviour in the field. A total of 29 different clones have been analysed. They belong to the Aigeiros, Tacamahaca, Leuce, and Leuce x Aigeiros sections. Clones of P. nigra, P. deltoides, and P. x euramericana hybrids were included from the Aigeiros section and clones of P. x interamericana were included from the Tacamahaca section. Different numbers of ramets were used for the different clones, including a total of 69 samples. From the analysis, 246 polymorphisms were obtained using two different primer combinations. The Dice similarity index was used to build a dendrogram using the unweighted pair group method average (UPGMA) clustering, where the clones are clearly grouped into sections and groups, and all the clones were identified showing different ramets at a Dice index higher than 90%. The genetic similarity level was higher than 50% among sections, higher than 70% among groups, and higher than 75% for those clones belonging to the same group. In the Aigeiros section, the P. nigra clones share a total of 39 polymorphic bands, 59 bands for P. deltoides, and 30 bands for P. x euramericana. The P. x interamericana clones share 8 bands with the rest of the clones from the Aigeiros section and 60 bands between them. Comparing the different groups, P. x euramericana clones are different in 12 bands with P. nigra, and in 5 bands with P. deltoides, and P. x interamericana clones are different in 9 bands with the P. x euramericana, in 30 bands with P. deltoides, and in 44 bands with P. nigra.
N. Anselmi1, M. Nasini1, A, Vannini1 and M. Sabatti2
1Diparimento di Protezione delle Piante, Università degli Studi della Tuscia, Viterbo, Italy
2Dipartimento di Scienze dell'Ambiente e delle sue Risorse, Università degli Studi della Tuscia,
Viterbo, Italy
Investigations have been carried out on the effects of elevated atmospheric CO2 on natural attacks of various leaf diseases on Populus spp. A poplar plantation was established in central Italy with three poplar species, cultivated in plots with enriched carbon dioxide (550 ppm) or ambient atmosphere. The diseases considered are: rusts (Melampsora allii-populina) on Populus nigra, clone Jean Pourtet, and on P. x euramericana, clone I-214; leaf spots (Marssonina populi-nigrae) on P. nigra Jean Pourtet, and Marssonina castagnei on Populus alba clone 2AS11; and viruses by Poplar Mosaic Virus on P. x euramericana I-214. Elevated CO2 level reduced the Melampsora attacks, although differences were not statistically significant. No effect of the CO2 concentration on attack intensity of poplar mosaic virus and Marssonina spp. was evident. The incubation period of the latter pathogen under elevated CO 2 seemed shorter than in the ambient atmosphere.
F.A. Aravanopoulos1, D. Lin2 , L. Zsuffa2 , and M. Hubbes2
1Department of Forestry and Natural Environment, Aristotle University of Thessaloniki, Thessaloniki, Greece
2Faculty of Forestry, University of Toronto, Toronto, Canada
This study reports the identification of willow clones selected for biomass short-rotation intensive culture plantations and a comparative analysis among different approaches for clonal identification. In particular, seven willow clones (three Salix eriocephala, two S. exigua, one S. eriocephala x exigua, and one S. exigua x eriocephala clone) were employed to record leaf morphology data (leaf length, leaf width, petiole length, distance from leaf base to leaf widest point, number of teeth per centimetre, stipule length, stipule width), iso-enzyme data from 10 enzyme systems (ACO, ACP, ADH, CE, GOT, PER, 6PGD, PGI, PGM, SDH), and RAPD data from two primers (Chl-2, Chl-4). Univariate statistical analysis of the morphological data showed that leaf parameters were unable to discriminate the clonal material. Fifteen variable loci were scored in the 10 enzyme systems studied. All clones presented unique multilocus isoenzyme genotypes with differences from each other ranging from 7 to 13 loci. By using two primers, 15 stable and repeatable RAPD loci were revealed. Six out of seven clones (86%) presented unique multilocus RAPD genotypes, while differences among clones ranged from 2 to 13. Leaf, isoenzyme, and RAPD data were subjected to principal component analysis, the latter two data sets after vector transformation. In all cases most of the variability was resolved in low multidimensional space, in particular 99% of leaf variability, 72.5% of the isoenzyme variability, and 89% of the RAPD variability in the first three axes. In general, three groups could be identified: the S. eriocephala and the S. eriocephala x exigua clones, the S. exigua clones, and the S. exigua x eriocephala hybrid. The conclusions of this study were: (1) leaf parameters were not suitable for clonal identification, (2) all clones were uniquely identified with 30-loci genotypes, (3) RAPDs were much more polymorphic than isoenzymes since there were 1.5 variable loci per enzyme system and 7.5 RAPD loci per primer.
Par Aronsson and Kurth Perttu
Department of Short Rotation Forestry, Swedish University of Agricultural Science, P.O. Box 7016, SE-75007 Uppsala, Sweden
Building complex treatment plants or landfills that meet the needs for satisfactory handling of wastes is very costly. Consequently, it is necessary to find much less expensive and more "natural" ways of waste treatment, which are efficient enough to be an alternative to complex technical solutions. One such method is the use of vegetation filters, regularly harvested, that remove unwanted, polluting subjects from the system. A crop used as a vegetation filter should neither directly nor indirectly be used as a food crop. Short-rotation willow coppice (SRWC), consisting of different species and clones of Salix, meets most of the requirements (non-food crop, efficient nutrient uptake, selective heavy metal uptake, high evapotranspiration rate, potential bioenergy fuel). Because of the presence of pathogens in municipal wastewater and sludge, attention must be paid to storage and distribution of this type of waste. In Sweden, trickle irrigation of wastewater is only occasionally accepted and instead, different types of drip irrigation techniques have been adopted. Sludge has to be treated or stored before it is regarded as safe. Humans could be infected after direct contact with the pathogens, which might happen during storage, by sprinkler irrigation through aerosols, and/or after ingestion of contaminated drinking water or swimming water. Indirectly, humans might be infected through zoonotic transfer of pathogens via livestock and pets. When localising vegetation filter systems in the landscape, it must be ensured that pathogens cannot affect humans. From our experiences and results so far, the following conclusions can be drawn:
S. Augustin1 , P. Faivre Rampant2 , A. Delplanque1 , M.C. Lesage3 , M. Villar3 , and C. Bastien3
1INRA, Unité de Zoologie Forestière, Ardon, France
2Université de Nancy 1, Laboratoire de Biologie Forestiére, Nancy, France
3INRA, Unité d'Amélioration, Génétique et Physiologie Forestières, Ardon, France
The leaf beetle Chrysomela tremulae is a serious pest of poplars in France causing significant defoliation that could prevent plantation establishment and decreasing biomass production in short-rotation coppices. Studies have revealed significant differences in responses among poplar species and hybrids, so learning about the host plant resistance and its genetic variation is a first step in achieving selection for durable resistance. To determine the genetic basis of inter-American inter-specific hybrids to C. tremulae, an experimental trial was installed in INRA Orléans to evaluate chrysomelid damages in natural conditions. A study of the sensitivity of 180 progenies of an INRA interspecific family (Populus deltoides x P. trichocarpa) is underway. Ninety progenies have been already used to evaluate the level of sensitivity to C. tremulae in laboratory conditions by feeding adults through multiple choice bioassays. This study allowed the classification of the progenies according to their level of sensitivity. To understand the genomic structure of resistance, two genetic maps have been realised using RAPD, RFLP, AFLP, and microsatellite markers: the first one corresponding to the female parent P. deltoides, and the second one corresponding to the male parent P. trichocarpa. Preliminary analysis of variance clearly showed a genomic region involved in susceptibility to C. tremulae in Populus trichocarpa. The next step will focus on the behaviour of the whole progenies in both natural and laboratory conditions to validate or not this first result and to research other putative statistical links between genomic regions and phenotypic data.
Gojko Avramovic, Vojsilav Guzina, Branislav Kovacevic, Leopold Poljakovic Pajnik, and Predrag Pap
Agricultural Faculty, Poplar Research Institute Novi Sad, Antona Cehova 13, P.O. Box 117, 21000 Novi Sad, Yugoslavia
In Yugoslavia, Dothichiza populea Sacc. et Br. is still a major problem in both poplar nurseries and in plantations. P. x euramericana genotypes, which are widely used in afforestation, are especially endangered (clones I-214, Robusta, 45/5 1, and Ostia). There is a permanent need to replace these genotypes with new ones that yield approximately the same or greater timber volume but that are far less susceptible to Dothichiza populea. To meet this need, the Poplar Research Institute in Novi Sad has designed a long-range program of selection and hybridisation. At the moment, more than a hundred clones are in the selection procedure. To get information on susceptibility to Dothichiza populea, 125 poplar genotypes (sections Aigeiros and Tacamahaca) and their rooted cuttings were transplanted into two separate plots in 1975. Between 1997 and 1999, on 2-year-old plants, the total number of necroses caused by Dothichiza populea attack was recorded. Fungal infections were spontaneous. The number of necroses was recorded each year between February 23 and March 4. Based on the number of necroses, a relatively great variability of tested clone susceptibility was observed. There were no necroses on seven genotypes in 3 years, and this group of clones was classified as "unsusceptible." In 33 genotypes, only 1-3 bark necroses were identified, and they were classified as "low susceptible" clones. The clones with 4-9 bark necroses were classified in the group of 35 "susceptible" clones. The greatest number of clones (50) had more than 10 necroses in the bark tissue (clone I-214 had up to 70 necroses), and they were classified as "highly susceptible" clones. The number of clones in the groups "unsusceptible" and "low susceptible" (40 clones) leads to the conclusion that a sound basis has been created for the solution of the problem caused by Dothichiza populea.
Istvan Bach1, Gaspar Bagamery1 Sandor Bordacs1, Erno Gabnai1 Attila Borovics2, Jozsef Gergacz2
1National Institute for Agricultural Quality Control, 1024 Budapest, Hungary
2Forest Research Institute, Research Station, 9601 Sarvar, Hungary
The gene preservation program was initiated in 1997. In the program we combined the scientific description of genotypes and ex situ conservation with the promotion of the production of propagating material intended for the replanting of endangered species.
A detailed accession record was made on each specimen (genotype) chosen and their ex situ conservation and testing for species identity by DNA analysis is in progress depending on the financial resources available. To date 214 genotypes were found to be true to type using B. Heinze's method and further 200 collected samples await analysis. A central gene archive (ERTI-Sárvár) and regional gene collections (Derecske, Fadd-Tolna, Sárvár) were established. Preservation is carried out both in juvenile stage (stool bed) and adult tree stage.
Law N° LIV 1996 on nature conservation requires, that forest owners must use indigenous species for afforestation in the protected areas of flood plains e.g. Populus nigra. Therefore the demand for both generative and vegetative propagating material is increasing steadily. Our working group has called attention to the occurring introgression due to Populus x euramericana cultivars. We recommended the use of easy to root genotypes that were found to be true to species by DNA analysis. Several ecologists debate the use of vegetative propagating material, therefore the use of seedlings is also significant, which is also a cheaper method. Seedlings were carried out by a non-random sampling for a DNA test. The samples were selected per 10 000 seedlings, in total 49 samples for DNA tests. We analysed specimens of extra size and peculiar morphological characteristics and found only 1 tree as a hybrid. By the number of samples taken the results can only be regarded as representative. A 0.6 ha stool bed containing clones of 40 DNA tested specimens was also established and the establishment of a clonal seed orchard containing clones of 45 genotypes is in process. The advantage of vegetative reproductive material of good growth parameters is that it better survives after the sometimes 1-3 months long and 2-4 meters high inundation by flood waters, than the smaller seedlings
Result data based on regions are presented. The populations in the Danube valley are well represented, so in the next phase we shall emphasise work on populations living along the river Tisza and its tributaries. Based on the collected samples we shall make preparations to carry out DNA testing of chloroptasts in order to estimate the genetic diversity.
John J. Balatinecz1 , Andre Leclercq2 , and David E. Kretschmann3
1Faculty of Forestry, University of Toronto, Toronto, ON, M5S 3B3, Canada
2Centre de Recherche de la Nature, des Forets et du Bois, B-5030 Gembloux, Belgium
3USDA Forest Service, Forest Products Laboratory, Madison, WI 53705, USA
Poplar wood is suitable and is utilised for a broad range of forest products world-wide. The utilisation of any species is governed by a number of factors, such as basic wood properties, overall quality, quantity and price of the resource, available processing technologies, local as well as international market conditions for the products, and the availability and price of competing products. The combined influence of these factors during the past 5 decades created a favourable environment for substantial growth in the poplar using industries globally, which is now stimulating major interest and investment in poplar growing. The many and varied uses of poplar wood include pulp and paper, lumber, veneer, plywood, composite panels, structural composite lumber, containers, pallets, furniture components, match splints, chopsticks, etc. The high cellulose and relatively low lignin content make poplars well suited for pulp and paper products. Poplar wood can be pulped by all commercial pulping methods, such as mechanical, semi-chemical, sulphate, and sulphite processes. Poplar pulps, in turn, are utilised in fine papers, tissues, paperboard, newsprint, and packaging papers. Poplar kraft pulps, when blended with softwood kraft, are particularly well suited to fine paper manufacture because of inherently desirable properties such as excellent sheet formation, high opacity, good bulk, and good printability. Recent technical advances in anthraquinone-catalyzed sulphite pulping are helping to increase pulp yield and strength properties of paper. While poplar wood continues to be an important raw material in the traditional lumber, veneer, and plywood industries, the most remarkable "success story" in poplar utilisation is the phenomenal growth of the oriented strand board (OSB) and the structural composite lumber industries (e.g., composite I-beams, laminated veneer lumber or LVL, laminated strand lumber or LSL) in North America during the last decade. These products and their industries have grown to multibillion dollar scope in annual product value and are now the largest users of poplar fibre. One of the many advantages of composites is that they use wood fibre more efficiently than sawn lumber, and greater product uniformity is achieved through highly automated manufacturing processes. Future prospects for growing and utilising poplar fibre resources look excellent. On the resource production side, opportunities for genetically modifying important wood properties, such as chemical composition, fibre quality, and natural durability of wood, can now be realised. On the resource utilisation side, high value engineered composites and high yield pulp and paper products will represent the strongest growth sectors in poplar utilisation during the coming decades.
Victoria Baonza Merino and Antonio Gutierrez Oliva
Dpto. Industrias Forestales, CIFOR-INIA, Apdo. 8. 1 1 1, 28080 Madrid, Spain
Poplar veneer yields from an industrial peeling operation were analysed in several trunk sections up to a height of 12 m. Peeling was carried out with 13 clones of genus Populus from the Populetum of Zamadueñas (Valladolid, Spain). The wettest veneer was automatically removed, and this material was visually classified according to the required industrial quality. Clones showing the highest wet veneer percentage (more than 40% in some cases) were Flevo, Dorskamp, 1-476, and 1-Z. On the other hand, clone Lux showed the smallest values, about 7%. In clones 1-214, Mc, Campeador, Canada Blanco, 1-262, PA-1, 1-Z, and Lux, more than a quarter of the total number of veneers obtained were of first quality. In relation to veneer yield, there were no pronounced differences among clones. Veneer yields from logs of a trunk up to 12 m in length averaged 60 to 70% in volume. In general, the best performance was found in the middle to lower zone of the trunk. However, optimal yield was found to be maintained even above 10 m in trunks in clones 1-214, Flevo, Mc and PA-1.
Gabriel Bascur B., Francisco Tapia F., and Carlos Covarrubias Z.
Agricultural Engineers M.Sc., CRI La Platina, INIA, Santiago, Chile
To improve the use of soil in a forest of poplars, systems associated with crops were developed, and the effects of different crops on the growth of the trees were evaluated. In poplars of the clone I-488 in the first and second years of the plantation, established at a density of 278 trees/ha (6 x 6 m), the effect of annual associated crops was studied. The annual crops included onion, tomato, sweet corn, corn, green beans, dry beans, potato, wheat, broccoli, cauliflower, lettuce, beans, pea, oat-vetch, Italian squash, fresh corn, and similar crops. The effect on the crops was evaluated through the yield of each species; for the poplars the diameter at breast height (dbh) and at the base of the first branch, total height, and height to the first branch were evaluated. For the agro-forestry system, the incidence of photosynthetic active radiation (PAR), effect on the fertility of the soil, variation of the environmental and soil (30 cm depth) temperature and fluctuations of the water table were measured. The yields obtained in each crop in the first year of evaluation were not affected; in the second year, a negative effect was observed in some crops from the spring season. In relation to the growth of the trees, there were no statistical differences in comparison to the control without crop; however, some species showed a significant and positive effect on dbh in the first year (green beans and onion). For the rest of the variables, differences were not apparent in either of the 2 years. Regarding the PAR, during the first year, the trees did not interfere with the incident light on the crops. In the second year, an effect was observed only from spring, when the incident PAR decreased by between 10 and 50%. The results obtained in these 2 years show that the poplars are not affected by the competition of the associated crops and that the latter reduce their yield only from the spring season in the second year.
Vasile I. Benea, Alexandru-Marius Coro
Statiunea de cercetäri pentru plop si salcie Cornetu, Bucharest, Romania
In the national forestry research program are included, both the `in situ' and `ex situ' native poplars genetic resources. So far, the results obtained in `in situ' stands, covering all native poplars (white, grey, black, aspen), which include 43 populations with 208.5 ha (approx. 0.4% from the total area), have been published already.
The present paper deals with the performances obtained in the Arge valley, which crosses the territory of the Cornetu Station, 20km from Bucharest.
They are, mainly, the following:
1. 17 target trees of 4 Populus alba clones: Ro-345, Ro-361, Ro-366 and Ro-D18;
2. 22 quantitative and qualitative phonotypical indices of the trees: form, size, colour of the stem, crown branches, bark and tree health;
3. 7 qualitative indices of the basic traits, with obvious genetic importance: straightness, slenderness and oval form of the stem, stem pruning/height ratio, branch thickness and tree health;
4. Qualitative value of the clonal-stands: Ro-345 superior, Ro-361, Ro-366 and Ro-018 medium-superior.
Vasile I. Benea1 and Victor Savulescu2
1Statiunea de cercetäri pentru plop si salcie Cornetu
2Instjtutul de cercetãri si proiectäri Delta Dunãrii, Tulcea, Romania
The paper deals with the results obtained in the trials of short-rotation plantations (1-5 years) in the Danube Delta. The tested species and clones are: Populus x euramericana Robusta Ro-16, I-214, and Sacrau-79; Populus deltoides I-69/55; and Salix alba Ro-201, Ro-202, Ro-204, and Ro-326, all used in applied forestry. The main conclusions are:
1. The Danube Delta offers favourable pedo-climatic conditions for short-rotation plantations of poplars and willows;
2. The best results were obtained with Salix alba clones, with an annual above ground average yield of 27.9 to/ha (1 x 1 m) to 42.0 to/ha (1 x 0.5 m); Populus clones produced 16.3 to/ha to 32.3 to/ha;
3. The most productive species and clones are: Salix alba Ro-326 (46.6 to/ha/year) and Populus deltoides I-69/55 (34.4 to/ha/year);
4. The 2-year rotation age is more favourable than that of 1 year for above ground yield biomass, which was 0.2-1.9 times more for willows and 0.5-0.9 times more for poplars.
C.C. Beno1, M.C. Coleman2, and A.L. Friend3
1University of Wisconsin-Stevens Point, Stevens Point, WI, USA
2USDA Forest Service, Savannah River Institute, New Ellenton, SC, USA
3Mississippi State University, Mississippi State, MS, USA
Root proliferation in enriched nitrogen (N) microsites has shown a varied degree of response. We hypothesise that cottonwood roots will proliferate in enriched N microsites and that this root proliferation response is negatively related to whole plant N status. To test our hypotheses, a cottonwood plantation was established and plots within it received 0, 50, 100, and 200 kg N/ha. Time-release fertiliser was used to prevent disturbance effects associated with large pulses of N. To create an N enriched microsite, 90 ml of 7mM N solution (1:3 ammonium:nitrate ratio made from NH4:NO3 and Na NO3 ) was injected into the soil. A second microsite received 90 ml N-free control solution (NaCl). The solutions were applied at two random locations along a clear, plastic minirhizotron. The minirhizotrons were located on one side of the tree row and placed horizontal to the surface at 15 cm depth. The two treatment solutions were also applied to similar locations on the opposite side of the tree row so that soil cores containing proliferating roots could be collected. Microsite treatments were applied to different locations at three phenological stages: leaf emergence, peak growing season, and budset. The microsites over minirhizotrons were monitored for fine-root production (sum of new root length), mortality (sum of missing root length), and standing crop (net amount of root length present). Cores were collected 3 weeks after application. Minirhizotrons treated at leaf emergence had greater production in N patches compared with the N-free controls, but not at peak growing season, suggesting that plant phenological stage could be a factor in root proliferation response to N enrichment. Plot fertilisation did not affect root sensitivity to microsite N, so the hypothesis was not supported. Also, no patch treatment differences were found for cores collected at any time in the season. Even though we know that cottonwood roots respond to N-enrichment in soil microsites, our findings from the field indicate that this response signal is difficult to detect within the noise of natural spatial and chemical variation in soil properties and the ability of soil to quickly buffer the addition of inorganic N. Therefore, larger concentrations of N in microsites and more careful monitoring and sampling may be required to rigorously test the hypothesis.
Bill Berguson
University of Minnesota, Natural Resources Research Institute (NRRI), Duluth, MN 55811, USA
The Minnesota Hybrid Poplar Research Cooperative (MHPRC) was formed in 1996 to improve poplar genetics, increase yields, and provide technical assistance to cooperative members and the public. Genetics research being done by the MHPRC includes testing of native cottonwood sources, breeding of interspecific hybrids, and field-testing of new poplar clones. We are currently attempting approximately 150 crosses annually using native P. deltoides as the female and P. maximowiczii and P. nigra as males in greenhouses at NRRI. Also, backcrosses of P. deltoides x maximowiczii hybrids to P. deltoides are being done to produce clones having higher resistance to Septoria canker. Of the 150 crosses made annually, our target is a minimum of 60 families having 100 seedlings per family for a total of 6,000 genotypes produced each year. Planting of field tests throughout Minnesota began in 1999 to evaluate these genotypes. In addition to breeding, clone tests have been established at 13 sites since 1997. These trials include native P. deltoides selections, P. deltoides x maximowiczii hybrids, and two commercial standards (DN34 and NM6). Data from our trials suggest that significant improvements in yield over the current commercial clones can be made. Results after 4 years of testing will be presented. The MHPRC is also conducting research to assess the nutritional needs of poplar plantations and improve cultural practices. Early results of fertilisation research at two sites suggest that yield can be increased by as much as 70% over unfertilised plots. We have established 16 fertilisation studies across a wide range of soil types since 1997. The goal of fertilisation research being done by the MHPRC is to develop tools to allow assessment of nutritional status and develop recommendations for supplemental nutrition. Research on cultural practices includes studies to test the phytotoxicity of new herbicides and optimise their effectiveness. The MHPRC has established an extensive network of growth and yield plots of clones recently recommended for commercial planting. Yield studies of these clones were established in 1995 and annually thereafter to assess the potential to improve yields over current commercial standards. Growth data and projections of final yield will be presented.
Egbert Beuker, MaUi Haapanen, Jan Hynynen, Pertti Pulkkinen, and Lars-Göran Stener
Finnish Forest Research Institute, Punkaharju Research Station, Finlandiantie 18, FIN-58450 Punkaharju, Finland
European aspen (Populus tremula) is the only species of the genus Populus that occurs naturally in Finland. Aspen, however, has never had much economic importance in Finnish forestry. Only during a few decades after the middle of the last century was there a short boom in aspen cultivation for raw material for the match industry. This was after hybrid aspen (P. tremula x P. tremuloides) was found to have superior growth compared to the pure species. After the decline of the match industry from the 1970s on, the interest in aspen disappeared again. Because aspen was considered a weed, it was mostly removed from the forests. Presently aspen stands cover about 60,000 ha, which is only 0.3% of the Finnish forest area. The appearance of aspen decreases from south to north. It is estimated that the standing volume of aspen in Finland is about 21 mill. m3, which is only 1.2% of the total. Since the 1990s, there is again a growing interest in aspen, this time as raw material for the pulp and paper industry. Aspen has been found to be very suitable as a raw material for new lean technologies in the paper production process, resulting in new grades of fine printing paper. The fibre morphology is especially important. The wood quality of naturally grown aspen is, however, very variable. Little was known about the causes for this variation (genetic vs. environmental). Recent studies using three replicated clone trials with hybrid aspen in Sweden (age 7 to 13 years), consisting of 18 clones, estimated the genetic parameters for some important fibre and yield traits. The estimates for clonal heritability for fibre and yield traits ranged from 0.42 to 0.86 and from 0.38 to 0.77, respectively. Between some of the fibre and growth traits, a strong correlation was found. Using data from the aspen and hybrid aspen stands (full-sib families) that were established during the 1950s and 1970s, growth potentials for southern Finland were estimated. Under good growing conditions, the wood production for hybrid aspen was found to be nearly twice that of native aspen. Hybrid aspen also grows faster than any of the three dominant tree species in Finland: birch, Norway spruce, and Scots pine. The profitability of aspen and hybrid aspen compared to the other species depends, of course, on developments in wood prices. At present price levels, hybrid aspen offers a good alternative. Aspen is probably the best alternative for reforestation of spruce sites affected by the Heterobasidion spp. (formerly Fomes spp.) root rot. Besides its promise as raw material for the pulp and paper industry, aspen is currently also of interest for the enhancement of biodiversity in Finland. When individual trees or small stands are left standing during forest harvesting, they offer niches for many species of insects, birds, and fungi.
Bixia Xiang1 , Min-ren Huang2 , and Ming-xiu Wang2
1Michigan Technological University, School of Forestry, Houghton, MI 49931, USA
2Key Laboratory of Forest Tree Genetics and Genetic Engineering, Nanjing Forestry University, Nanjing, 210037, China
There are two serious problems in Populus deltoides breeding in China: (1) narrow genetic basis for parent selection and (2) lack of detailed study on genetic variation for important traits. To broaden our genetic base, we collected plus open-pollinated P. deltoides families in the south of USA where P. deltoides grows naturally along rivers. This paper has studied genetic variation by use of both RAPD molecular markers and quantitative traits (height and diameter). To establish the linkage between the molecular markers and QTLs (quantitative trait loci), we used both the MB (marker-based) method and RAPD-based analysis to detect the probable number of QTLs related to plant height and diameter of P. deltoides and study their relationships. The main results are listed below:
(1) Fourteen out of 300 (10 bp) random oligonucleotide primers from PCR were screened for RAPD analysis among 11 open-pollinated P. deltoides families, 163 clones (5 P. cathayana clones used as contrast). Each primer produced 1-12 bands that ranged in size from 200 to 2000 bp. Thirty-four out of 97 (35.1%) bands amplified by 14 primers were polymorphic, and 10 out of 34 polymorphic bands were low frequency bands (<15%). Different primers had different frequencies for polymorphic bands, which may be related to regions of the genome. RAPD analysis allowed one to discriminate among all tested clones.
(2) The average Nei's Genetic Distance (D) between out-group and every family was 0.2. The D among 11 families ranged from 0.0164 to 0.1751, and the UPGMA dendrogram based on the 12 x 12 genetic distance matrix was effective in differentiating the out-group from 11 families. There were no obvious relationships within the 11 family dendrogram and the family's geographical location. For most families and clones, the genetic distance among clones from the same family was smaller (0.0606-0.5000), than the genetic distance among clones from different families (the largest was 0.8873).
(3) Variance analysis indicated that the family and the clone-within-family source of variation is highly significant for two traits (height age 1, diameter age 1). The data of variance component showed that the genetic variation exists mainly in clones within-family, not among families. So, it is possible to achieve genetic gain through selection among clones. The broad-sense heritabilities (h 2 ) of diameter is larger than that of height, which suggests that diameter growth of cottonwood clones is more controlled genetically than height growth. Estimates of non-additive genetic variance were small.
(4) According to one-way ANOVA, 9 out of 34 markers (26.47%), were significantly related to height and diameter (P<0.05) separately. Through two-way ANOVA, 7 1 out of 1,122 (6.24%) two-markers-recombination were detected linked with QTLs for height (45) and diameter (26) (P<0.001). Two-way ANOVA failed to detect interactions among most of the QTLs discovered by one-way ANOVA. The quantitative traits were controlled by many loci, and these loci were likely distributed randomly in the genome.
(5) The P value varied with larger range (0.0001-0.9239) and there are few markers related to quantitative traits with very low P value (P<0.00 1). Height and diameter of P. deltoides appeared to be under the control of many quantitative trait loci (QTLs), and few markers can explain more genetic variation. The results were consistent with other results based on genetic linkage maps, and they are potentially valuable for design of poplar breeding strategies.
(6) Four markers (L7, L8, L25, L13) were significantly related to QTLs of both diameter and height (P<0.05), esp. L13 and L25, which were highly significantly related (P<0.01) to QTLs of diameter and height. It seemed that one marker is related with two or more traits.
Wout Boerjan
Department of Plant Genetics, Flanders Interuniversity Institute for Biotechnology, Ledeganckstraat 35,
9000 Ghent, Belgium
According to the State of the World's Forests report (FAO), global forest cover is decreasing annually by 12 million ha, while the demand for wood and wood products is increasing steadily. It is therefore necessary to improve the yield of fast-growing trees that can be grown in intensively managed plantations.
Conventional breeding consists of the identification of plus trees, the generation of interspecific and intraspecific hybrids, and the selection of superior hybrids. Especially for forest trees, breeding cycles are long, mainly because of the long generation times and the fact that important traits, such as wood quality, can only be evaluated at rotation age. When viewed at the molecular level, conventional breeding combines a number of beneficial genes, residing from different parents, into a single hybrid clone. The principal question to be resolved is "How to identify the genes that underpin important traits in a forest tree; i.e., that can improve yield or quality?" Most fundamental knowledge on the function of genes comes from extensive research on model plants such as Arabidopsis. For Arabidopsis, the complete genome has been sequenced, and the function of approximately 50% of the genes is known. Many of these genes or homologues are candidates to be introduced into the poplar genome by genetic engineering, to alter quality or yield. For example, modifying the expression levels of the genes encoding enzymes of the lignin biosynthesis pathway has been shown to improve the quality of wood for the production of paper. Other studies have shown that insect resistance and growth can be improved by emphasizing certain genes in poplar. Experimental field trials have been established for several transgenic poplar clones.
Another promising field of research is based on molecular marker approaches. Apart from their value in fingerprinting individual clones for clone identification purposes, molecular markers have made it possible to create genetic maps. These genetic maps are extremely valuable to dissect the genetics of complex traits. Although until now, the direct value of genetic maps to improve poplar breeding has been limited, they hold an enormous potential as they get more refined and many more genes are being mapped. As a first step to identify genes explaining important traits, several research projects aim at exploring a potential co-localisation of QTL for a given trait with genes identified through other methods (e.g., EST or micro-array projects). Such a candidate gene approach is now feasible to identify genes for disease resistance. In addition, the knowledge of the complete sequence of the Arabidopsis genome will make it possible to investigate to what extent the Arabidopsis and the poplar genomes are co-linear. If microsyntheny (similar sequential order of the genes) exists, it will be possible to use map-information from the Arabidopsis research field for poplar improvement.
One of the main challenges for future tree improvement programs will be to integrate the knowledge and experience from breeders with the increasing wealth of data being produced from molecular tools, to speed up the genetic improvement of trees.
Esteban D. Borodowski and Raul O. Suarez
Nucleo de Extension Forestal Delta, Proyecto Forestal de Desarrollo, S.A.G.P.y A., Argentina
The objective of this work was to evaluate the growth of two plantations of Populus deltoides Marsh. cv. Catfish 5, planted at two different densities. The experiment was performed at the First Section of the Delta Parana River Province of Buenos Aires, Argentina (34oS, 58oW). Mean annual precipitation and temperature was 1,021 mm and 16.5°C, respectively, and plantations are subjected to periodic flooding. The plantations were established in 1989 at two densities: i) 4 m x 4 m (LD: low density), and ii) 3 m x 2 m (HD: high density). In September of 1994, 95 trees of each treatment were marked at breast height (1.30 m). From this date until September 1999 (5 years), the circumference was measured at 3-month intervals (coinciding with the initiation of each annual station), using metric tape with 0.1 cm precision. At the beginning of the measurements, LD had 549 trees/ha with a mean diameter of 13.59 cm, 7.96 m 2 /ha basal area, and 206 Reineke Density Index. HD had 1,517 trees/ha with a mean diameter of 13.36 CM, 21.27 m 2 /ha basal area, and 555 Reineke Density Index. There were no differences of individual growth between treatments at the beginning of the measured period, evaluated by the mean diameter.
Annual mean diameter growth was 24.57 and 11.84 mm for LD and HD, respectively, during the first year (Sept. 1994 - Sept. 1995); 18.44 and 8.22 mm for the second year (Sept. 1995 - Sept. 1996); 15.48 and 6.32 mm for the third year (Sept. 1996 - Sept. 1997); 11.91 and 4.70 mm for the fourth year (Sept. 1997 - Sept. 1998), and 10.14 and 5.16 mm for the fifth year (Sept. 1998 - Sept. 1999). The growth was higher in LD than HD (P<0.01) in all growing periods. The higher increments occurred in the spring - summer period (98% of the total annual growth) depending on the year. This tendency increased as plantation development advanced and was higher in HD compared with LD. The results obtained for this particular site, age, and density conditions allow us to deduce that thinning would produce an increase of diameter growth, as LD showed a higher diameter growth than HD.
Esteban D. Borodowski and Raul O. Suarez
Nucleo de Extension Forestal Delta, Proyecto Forestal de Desarrollo, S.A.G.P.yA., Argentina
Our objective was to define a management range for cottonwood (Populus spp.) plantations using the Reineke Density Index (RDI). This method considered density as the number of trees per unit of area and as an expression of the competition within a plantation. To define a management range utilising this method, published data sets from the U.S. and Argentina, which proposed optimum management for cottonwood plantations, were reanalysed. This work included a wide range of clones, different initial spacing, and different soil types. Management range (number of trees per hectare) was converted into RDI, and the average RDI for each region was calculated. Maximum and minimum values of management of RDI for the U.S. and Argentina were defined. The estimated management range for the U.S. was 193 to 356 RDI and for Argentina was 250 to 380 RDI. Considering the average of the minimum and maximum values could be a first approach to establishing a management range for Populus spp. plantations. More investigations in this subject area will help improve management in this species.
Esteban D. Borodowski and Raul O. Suarez
Nucleo de Extension Forestal Delta, Proyecto Forestal de Desarrollo, S.A.G.P.y A., Argentina
The objective of this work was to evaluate the seasonal growth of three plantations of different clones of Populus deltoides (cv. Stoneville 71, cv. Catfish 5, and cv. I 72/51) planted at the same density. The experiment was performed at the Second Section of the Delta Parana River Province of Buenos Aires, Argentina (34oS, 58oW). Mean annual precipitation and temperature were 1,021 mm and 16.5°C, respectively. The plantations were established in 1993 with a spacing of 3 m x 5 m. In September of 1997, 110 trees of each treatment were marked at breast height (1.30 m). From this date until September 1999 (2 years), the circumference was measured at 3-month intervals (coinciding with the initiation of each annual station), using metric tape with 0.1 cm precision. At the beginning of the measurements the plantation of P. deltoides cv. Stoneville 71 (ST.71) had 612 trees/ha with a mean diameter of 10.40 cm, 5.21 m 2 /ha basal area, and 150 Reineke Density Index. The plantation of P. deltoides cv. Catfish 5 (CF.5) had 654 trees/ha with a mean diameter of 7.91 cm, 3.22 m 2 /ha basal area and 104 Reineke Density Index. The plantation of P. deltoides cv. I 72/51 (I.72) had 654 trees/ha with a mean diameter of 9.66 cm, 4.81 m 2 / ha basal area, and 143 Reineke Density Index. There were differences of individual growth between treatments at the beginning of the measured period, evaluated by the mean diameter (P<0.01). Annual mean diameter growth was 33.4, 25.56, and 19.87 mm for ST.71, CF.5, and I.72, respectively, during the first year (Sept. 1997 - Sept. 1998) and 26. 02, 22.57, and 22.80 mm for the second year (Sept. 1998 - Sept. 1999). The higher increments occurred in the spring - summer period (92 to 99% of the total annual growth). This tendency increased as plantation development advanced. CF.5 and I.72 presented principally spring growth (73 to 79% of the total annual growth) depending on the year; ST.71 distributed its growth in spring and summer (57 vs. 43%, respectively) as the mean of the 2 years of measurements. Results obtained allow us to deduce that the clone had a direct effect on the seasonal growth distribution under these particular conditions.
Esteban D. Borodowski and Raul O. Suarez
Nucleo de Extension Forestal Delta, Proyecto Forestal de Desarrollo, S.A.G.P.y A., Argentina
The objective of the present work was to evaluate the wood and animal production of a silvo-pastoral system in the Argentine Delta Region. The experiment was conducted in Campana, located in Buenos Aires, Argentina (34oS, 58oW). Mean annual precipitation and temperature there were 1,021 mm and 16.5oC, respectively. This area is characterised by periodic flooding, so the fields were protected to control this environmental factor. Plants of 1-2 years with roots of Populus deltoides cv. I 63/51 were planted at a density of 278 trees/ha (6 m x 6 m) after 1 year of mechanical fallow. Numerous pruning and thinning practices were done to obtain wood of high quality (trees with a diameter higher than 40 cm and straight and healthy wood). Natural grassland developed under the tree plantation, composed of valuable species as Lolium sp., Trifolium sp., Stipa sp., Lotus sp., Paspalum sp., etc. This grassland allowed the implementation of a silvo-pastoral system, where forest production is combined with the production of breeding cattle. Cattle were introduced when the plantation was 3 to 4 years old. Animals were pastured with oats (80 kg seed/ha in an area of 10 ha of 4-year-old cottonwood with 400 trees/ha (5 m x 5 m)). The percentage of births was 78%, with a mean animal production of 0.78 calves/ha/year and a weight of 170 kg/animal at weaning. Wood production at harvest for the Populus deltoides cv. I 63/51 plantation of 15 years old was: veneer production (diameter of 9 inches) - 250 t/ha (79%); saw log production (diameter from 6 to 9 inches) - 36 t/ha (11%); pulpwood production (diameter from 3 to 6 inches) - 31 t/ha (10%); total production - 317 t/ha (100%). The high wood and cattle production obtained in this experiment suggests this silvo-pastoral system for the Delta Region as an alternative to diversify the traditional production systems.
Chris Britt
ADAS, MAFF Drayton, Alcester Road, Stratford-upon-Avon, Warwickshire CV37 9RQ, UK
Agricultural overproduction in Europe has resulted in large areas of farmland being no longer required for food crops. In recent years, obligatory `set-aside' has been used as the main mechanism for controlling arable crop surpluses. Although this situation presents problems for policymakers, it also provides opportunities for environmental enhancement and production of non-food crops. Modern poplar hybrids are highly suitable for ex-arable land. Poplar wood has many potential uses and even the longest rotations are short, compared to those for other forest crops - increasing flexibility for integration into agricultural systems. Various studies have indicated that the economics of poplar production compare favourably with other forest trees and with most alternative, non-food crops. Poplars, therefore, offer an excellent opportunity for farm `diversification' and could provide raw materials for small-scale rural industries, increasing employment. Widespread production on surplus arable land could also make an important contribution to European targets for reductions in fossil fuel combustion, reducing CO 2 levels, and could make a positive contribution to trade balances by reducing import requirements for paper pulp and hardwood timber. Against this background, the European Commission decided to support a research project that further develops recent work on site suitability and economics of poplar production, and takes a broader look at all aspects of poplar production on farmland - including studies of environmental impacts, existing and developing markets, and the attitudes of farmers and the general public. This project, Poplars: a multiple-use crop for European arable farmers (acronym PAMUCEAF) (EC FAIR CT98-4l93), has six main objectives:
1. To examine current levels of demand for various poplar (Populus spp.) wood products - including veneers, sawn timber, fibre and wood chips for energy production - and identify likely future market trends.
2. To determine the potential for widespread production of poplars as a non-food crop for surplus agricultural land, in the light of current economic and political factors and under a reformed European `Common Agricultural Policy' - as proposed by `Agenda 2000'.
3. To determine the probable environmental impact of large-scale poplar production in agricultural areas -considering likely effects on soil and water resources, biodiversity, and landscapes.
4. To identify `key areas' for poplar production, using GIS software.
5. To assess the attitudes of farmers and the general public to a potential increase in poplar planting on farmland and identify their main objections to this crop.
6. To produce revised recommendations for poplar production on arable or mixed farms - ensuring maximum profitability, full integration with other farm enterprises, and environmental acceptability.
Amy Brunner, Jeff Skinner, Rick Meilan, and Steve Strauss
Department of Forest Science, Oregon State University, Corvallis, OR 9733 1-5752, USA
Sterility will greatly reduce ecological concerns over use of transgenic plantations, and consultations with U.S. regulatory agencies indicate that it is likely to be required for commercial use of trees improved via genetic engineering. Additionally, sterility would reduce genetic pollution from exotic, hybrid, or monoclonal plantations. The most widely applicable methods for engineering of sterility either inhibit the functions of genes necessary for fertility or specifically induce cell death in reproductive tissues. Despite strong indications that one or more of these strategies can be successfully applied to trees, it has not yet been demonstrated that any sterility transgene fulfils the basic requirements for commercial use as a long-term containment measure. For this, engineered sterility must be complete and stable over multiple rounds of vegetative propagation and growing seasons, it must cause no detrimental effects on vegetative growth, and successful transformation events must be identifiable via molecular tests when trees are still juvenile. The different strategies for engineering sterility have distinct advantages and disadvantages, and which method will be best for use in trees is unclear. Important factors, which may be more or less problematic depending on the sterility transgene, include: 1) the likelihood of causing detrimental vegetative effects, 2) applicability to diverse species, 3) ability to identify sterile trees prior to flowering age, 4) degree of sterility, and 5) stability of sterility. For this reason, we have been studying various methods for engineering sterility in poplars. Highlights of our results to date will be presented. These range from 5-year-old field tests of transgenic poplars with heterologous promoter::cytotoxin transgenes to tests of novel poplar gene constructs in early-flowering poplars and model annual plants.
Steven J. Brunsfeld1, Carina K. Anttila2, and Robert Drew1
1Department of Forest Resources, University of Idaho, Moscow, ID 83843, USA
2Department of Biology, University of Joensuu, Joensuu, Finland, 80101
Salix (willow) is the largest and most complex group of woody plants in the temperate zone. Willows have a highly important role in natural communities and are valuable in riparian revegetation and biomass production. Despite their importance, surprisingly little is known about their genetics. Knowledge of the fundamental genetic structure underlying presumed species, the relationships among species, and the role of evolutionary processes such as hybridisation is essential to the management of willows. In our research we have employed a multi-gene approach, including chloroplast and nuclear data, to infer genetic relationships and processes. Chloroplast DNA, commonly used in plant systematic, provides resolution of major divisions within the genus. Two major subgenera and groups within the more ancient subgenus Salix are revealed. However, relationships within the subgenus Vetrix are poorly resolved, presumably due to a more recent radiation of species. To date, two kinds of nuclear sequence data are being used: ITS and starch synthase. The latter is providing much greater resolution of closely related species. Taken together, the several data sets reveal differing levels of resolution among taxa, and cases of incongruence among data sets suggest the importance of hybridisation in the genus. In addition, substantial genetic differentiation has also been discovered within some taxa. For example, Salix eriocephala, used in biomass production, is not genetically uniform throughout its range. The implications of this variation are that breeding and management activities need to be built on a solid foundation of genetic knowledge.
A.D. Calderon, J.A. Bustamante, S.J. Micali, N.E. Riu, A. Somoza, and V. Settepani
Departamento de Producción Agropecuaria-C·tedra DasonomIaFacultad de Ciencias Agrarias -Universidad Nacional de Cuyo, Argentina
In the province of Mendoza, Argentina, forest activity is based almost exclusively in poplar cultivation. Several parcel tests were carried out in different places to compare the behaviour of different poplar clones of both local and foreign origins. Results obtained in parcels located in Villa Atuel (Department of San Rafael), Nueva California (Department of San Martin), and El Capacho (Department of San Carlos), where clones of Populus deltoides and of Populus x euramericana were tested, are shown here. Circumference and height of the trees were measured annually and attacks of Septoria musiva Peck (cancrosis) were registered. In Villa Atuel, the best yield in wood volume was obtained from Populus x euramericana cv. Cima. The most susceptible clone to cancrosis attacks was cv. Cima. The clones Conti 12 and Harvard were more resistant to this plant disease. In Nueva California, the best yield in wood volume was obtained by Populus x euramericana cv. Conti 12. Cancrosis attacks were not significant. In El Capacho, the best yield in wood volume was obtained by Populus x euramericana, cv. Guardi; cancrosis attacks were more severe in cv. Longhi, cv. Cima, cv. I-29, and cv. I-488.
M. Casado Sanz1 and A. Gutierrez Oliva2
1E.T.S. Ingenierlas Agraria, 34071, Palencia, Spain
2 Dpto. de Industrias Forestales, CIFOR-INIA, Apto. 8111, Madrid, Spain
In this work, new knowledge about growth stresses in the type Populus x euramericana is presented. In 200 Populus trees of the Populetum of Zaragoza (SIA-DGA) and of the Populetum of Valladolid (INIA) in Spain, a study was done on genetic and environmental influences on the development of longitudinal deforms (a measure of the internal tensions or growth stresses) determined in the periphery of the trunk. At the same time, the effects of the forestry station, clone, and the morphological features of Populus on growth stresses were studied. The influence of the station was observed; all the black poplars from the Populetum of Zaragoza had greater average tension than those from the Populetum of Valladolid. There was also an influence of factor clone which had a different behaviour in Canada Leonés (the longitudinal deformation was 25%). The morphological features (height, diameter, quadrature, symmetry of the top, volume of the top, volume of wood, inclination tree) of Populus associated with growth stresses are: the inclination of the tree and the symmetry of the top. Trees that are more inclined and trees that have asymmetrical tops have greater growth stresses. However, the height, diameter, quadrature, and volume of wood have no significant influence on growth stresses.
Edgardo Casaubon1, Gerardo Cueto2, Karma Hodara2, and Adrian Gonzalez1
1EEA Delta Del Paraná, INTA. C.C. 14. C.P. 1428, Campana, Argentina
2Departamento de Biologla, F.C.E.N.- UBA, Lab. 104, 4to Piso, Pabellón II, Ciudad Universitaria, CP 1428, Buenos Aires, Argentina
In the Paraná delta area, poplar commercial plantations are planted in highlands and in lowlands surrounded and protected by dams, occupying 14,000 ha in the zone. The greatest wood volume is assigned to sawmills and veneering, and a lesser proportion is assigned to grinding. This work is aimed at studying the relation between plantation site quality with damage caused by "Taladro de los Forestales" (Platypus sulcatus Chapuis), and the relation with other diseases, such as cankers, that affect the trunks until 2 m high and reduce the wood quality and/or quantity. The taladro is a small, cylindrical Coleopterous insect in the Platipodidae family. This insect burrows galleries within trunks, affecting wood quality, decreasing its commercial value, and producing important volume loss in adult plantations when infected trees break with the wind. It is considered the most important poplar pest in the region. We also analysed incidence of trunk disease, which causes cracks in the poplar trunks and bark death. Consequently, the commercial values of wood quality decrease and volume may be lost due to the windthrow of the infected trees. We carried out the study in a 2 ha plantation of Populus deltoides cv. Catfish-2, which is the most widespread clone in the delta area. The plantation was 12 years old; the plants were placed at 3 x 4 m intervals; and a direct relation was found among the forest site, the pest, and the disease.
The taladro attack was not at random because the most affected trees had greater diameter and height than those not infected, and they grew in soil types of albardón endicado. These trees showed the most active holes and cracks at gallery height, as a consequence of the wind. The percentage of infected plants was greater at the best plantation site, probably due to physiological causes, although plants affected by the pest had smaller diameters than the healthy ones. Low sites, typically from bañados protected by dams, had lower volumetric yields, fewer active holes, fewer plants broken by the wind at the height of galleries, and fewer cracks in the trunks.
Stefano Castiglione1, Tiziana Fossati1, Fabrizio Grassi1, Salvatore Bollotta1, Stefano Bisoffi2, and Francesco Sala1
1Dipartimento di Biologia Università degli Studi di Milano, Via Celoria 26, 20133 Milano, Italy
2Istituto di Sperimentazione per la Pioppicoltura, Strada Frassineto 35, 15033 Casale Monferrato (AL), Italy
Populus nigra L. is a tree of social and economic importance. It has direct economic values as a supplier of raw material for industries. It is a unique pioneer species of riparian ecosystems, which contribute to the natural control of flooding and water quality and which are characterised by a high level of diversity of fauna and flora. Some natural habitat may have been lost due to drainage of rivers. It is not known if the genetic diversity of the species has been reduced as a consequence.
In this work we studied the relationship between different populations of the same river, which arose from the recolonization of Europe by trees after the last glaciation, perturbation of riparian sites by human activities, seeds and pollen flow, and antropic dissemination. For the project we harvested and vegetatively replicated cuttings of two populations set along the Ticino River, which runs from the Maggiore Lake to the Po River. The two P. nigra populations are located 7 km from each other; the first wood is called "La Zelata" and the second "Bosco Siro Negri". About 80 P. nigra clones maintained in the repository of the poplar experimental station (Istituto Sperimentale per la Pioppicoltura) of Casale Monferrato (CN-Italy) were also analysed.
The strategy used in the present study to monitor the genetic similarity at molecular level utilises the microsatellite DNA. The microsatellites are particularly attractive in distinguishing differences inside a population or between two different populations, since the level of variation detected at microsatellite loci is higher than that detected by any other molecular assay, such as isozymes analysis. Microsatellites are highly polymorphic, tandemly repeated DNA sequences with a core sequence of 2-4 bases (GA, CTT, or GATA, for example). The polymorphism found in repeated DNA is due to variations in copy number of the core; for example, one tree may contain 10 copies of the repeat, whereas others may contain 11, 12, or more copies. The differences in repeat length can be visualised using the sequence tagged microsatellite sites (STMS) approach. For this PCR-based method, specific pairs of primers, which are complementary to unique flanking DNA sequences of the microsatellite, are used to amplify the fragment containing the microsatellite of the genome of P. nigra. Furthermore, microsatellites are co-dominant markers, so all the alleles present at the heterozygous state can be detectable. We used six pairs of primers to detect the different alleles of the populations, of the gene bank, and of the germinating seeds of three selected female trees of the "La Zelat" wood to detect if a putative dominant male exists in the population and the pollination is not a random event. The favourite individual will be detected comparing the microsatellite pattern of the seeds.
The molecular data produced were analysed with the most common statistical analysis packages for codominant markers such as Pop gene or Ntsys to determine genetic distance or similarity among individuals and between the two populations and the gene bank.
G. Castro1 and F. Paganini2
1Istituto di Sperimentazione per Ia Pioppicoltura, Strada per Frassineto 35 I-15033 Casale Monferrato (AL), Italy
2Istituto per la Tecnologia del Legno - C.N.R., Via Biasi 75, I-38010 San Michele all'Adige (TN), Italy
The authors investigated the properties of small glued laminated beams (80 mm in width, 115 mm in height, and 2 m in length) composed of seven mechanically graded laminations of poplar (Populus x euramericana, Neva clone) and eucalyptus (Eucalyptus grandis) in different combinations. Tests were carried out to determine their modulus of elasticity, bending strength, and shear modulus; in addition, the bonding reliability was evaluated by means of delamination and shear tests in the glue lines. The bonding quality was very high in all cases; the maximum structural efficiency was obtained when only 2/7 of the transversal section of the beam was made of eucalyptus (i.e., two outer laminations in eucalyptus and five in poplar).
Teresa Cerrillo
Buenos Aires, Argentina
Willows (Salix spp.) are interesting and promising forest trees because of their high growth rate, their good performance in lowlands, their capacity for use as a renewable source of short fibre and biomass for energy, their positive effect against the erosion, and a value in the landscape. There is broad variability in the Salix genus. However, the number of studied species and forms is very small, so the commercial clones in the world are based on a restricted genetic base. In this technical contribution, a breeding program is proposed that considers a recurrent selection method to obtain improved material and to help increase the variability for future breeding programs. For Salix humboldtiana, the only native willow in South America, the germoplasm collection would also contribute to its conservation.
R. Ceulemans and B. Gielen
University of Antwerpen, UIA, Department of Biology, Universiteitsplein 1, B-2610 Wilrijk, Belgium
Because of their prominent role in global bio-productivity and their complex structure and function, forests and tree species deserve particular attention in studies on the likely impact of elevated atmospheric CO2 on terrestrial vegetation. The need to assess the role of forests in the global cycling of carbon and how that role will change as the atmospheric concentration of CO2 increases has therefore spawned many experiments. In this contribution the results of field experiments on different poplar (Populus) species and hybrids over several growing seasons are reviewed. In particular the effect of elevated atmospheric CO2 concentrations on the growth, development, and productivity will be reviewed, but also some ozone responses will be presented. Most poplar species and hybrids seem to respond quite strongly to increased CO2 (and ozone) concentrations, but important species as well as clonal differences in this response have already been demonstrated. Experiments with trees in open-top chambers under field conditions have provided data on longer term responses to elevated CO2 under field conditions, have confirmed some of the conclusions from previous seedling studies, and have challenged other conclusions at a larger scale. Below ground responses seem to be extremely important because they directly affect the interacting cycles of carbon, water, and nutrients. Results from various studies (incl. from the literature) will be discussed, together with past and ongoing studies of our own research group within the frame-work of European funded research projects. Recent observations of a free air CO 2 enrichment (POPFACE) study on poplar trees will also be presented and discussed. Furthermore, some comparisons with responses of poplar to increasing tropospheric ozone levels will be made. Our current knowledge is sufficiently large with regard to how the carbon uptake process and individual tree growth respond under atmospheric changes, but more emphasis should be put in future experiments (such as FACE studies) on the interactions between various processes, as well as on below ground responses. Poplar has proven to be a very useful species in the studies of tree and ecosystem responses to increasing atmospheric CO 2 (and ozone) levels.
