Search

This paper aims to identify the hazelnut characteristics of four different populations (Agli-Tunuslar, Agli-Musellimler, Arac-Guzluk and Tosya-Kucuksekiler) in the North Western Black Sea Region of Turkey, one of the most important areas of economic interest for this species. There, the Turkish hazel (Corylus colurna L.) grows in its optimal conditions and reveals relatively high inter-population and intra-population variation in terms of nut characteristics. With the purpose of assessing variation, measurements were performed in four populations in Kastamonu district on 14 different nut characteristics (number of nuts per cluster, nut length (mm), nut width (mm), nut thickness (mm), shell thickness (mm), nut size (mm), nut shape, compression index, nut weight (g), kernel length (mm), kernel width (mm), kernel thickness (mm), kernel weight (g) and kernel ratio (%) of representative samples of the populations. Significant differences were found out among populations with regard to all of nut characteristics (p

Beech (Fagus sylvatica L.) is one of the most important forest trees in Bosnia and Herzegovina in both economic and environmental terms. The total area of forest in which beech is present is approx. 1,652,400 ha. There is a proportionate need to plant new forests and produce genetically high quality seed and saplings. Biochemical analysis of the genetic structure of eight populations of beech using ten enzyme systems from 16 isoenzyme gene loci revealed significant differences between the populations analyzed. Variance levels were high in some gene loci, while in some populations monomorphism was recorded only for individual gene loci. The average number of alleles per locus ranged from 2.1875 to 2.5625, and the average number of genotypes per locus varied from 2.6875 to 3.2500. The multilocus genetic diversity at the population level ranged from 63.276 to 162.001, and the genofund diversity varied from 1.2708 to 1.3416.The average differentiation value obtained for all populations was fairly low (Dj=5.81), indicating a percentage of overall variance of about 94.194%.

Genetic-physiological approach was used in the study of the quality of Serbian spruce seed (Picea omorika /Pancic/Purkynĕ), collected in the populations on the left bank of the river Drina. The seed originated from the three populations that represent the overall ecological and productive conditions of Serbian spruce populations in Bosnia and Herzegovina. Two natural populations were selected: Veliki Stolac and Gostilj, and one planted forest population in Srebrenica. The cones were collected in late autumn 2009 and early spring 2010. They were collected from five trees from Srebrenica and Gostilj, and seven trees from Veliki Stolac. Immediately after they were collected, the cones and seeds were processed and germination tests were done. Germination, germination viability and germination dynamics were studied in three categories of seed treatment: 1) control unit (just processed seed), 2) seed stored for six months at 0-4 oC, 3) seed stored for seven months at 0-4o C and treated with fungicide after five months of storing. The number of germinated seed was observed and noted on the third, fourth, fifth, seventh, tenth, fourteenth, twenty-first and twenty-eighth day. There were significant differences in germination dynamics at the population level and the level of treatment during the first couple of days of germination test. Fungicide (captan) acted as an inhibitor on seed germination process. The seeds originating from the largest population of Veliki Stolac showed the best response to storing treatment with fungicide related to germination dynamics. The seed originating from Srebrenica andkept at low temperatures 0-4 °C without treatment with fungicides showed the best result in germination. Regardless of the presence of differences in the dynamics of germination, significant differences in germination regarding different treatments on the last day of the test, were not recorded.

The study was carried out in Serbian spruce (Picea omorika Panc/Purkyn?) plantations in the western Serbia. The paper presents results of the analysis of crown development. The following elements were analyzed: total tree height, height of the crown base, absolute and relative crown length, maximal crown diameter, coefficient of crown spreading and degree of crown girth. We discuss approaches to the modeling of tree crown growth and development, growing under favorable environmental and stand conditions, without anomalies in development. In order to establish the relationship between analyzed factors, regression analyses were applied. Data fitting was by the analytic method, by the implementation of Prodan?s functions of growth, linear and parabolic function. Received models can be used for the simulation of various growth and developing processes in forest.

The aim of this study is analysis of inter-population variability of Scots pine (Pinus sylvestris L.) using morphometric parameters of cones and seedlings originating from seven populations in Serbia. The analysis of 1960 cones and their seeds was performed as well as the analysis of morphometric parameters of seedlings (height and root neck diameter) that were produced from this seed. Based on the obtained results the significant differences were noticed in the values of analyzed characters for each population separately. The biological similarity or distance regarding the analyzed characters showed a significant population differentiation. By presenting the preliminary knowledge on the genetic variability of the study populations, the reported results will contribute to better understanding of the significance of the analyzed characters in the population differentiation. U okviru ovog rada prikazani su rezultati analize međupopulacionog varijabiliteta belog bora (Pinus sylvestris L.) upotrebom morfometrijskih parametara šišarica i sadnica koje vode poreklo iz sedam populacija u Srbiji. Izvršena je analiza 1960 šišarica i njihovog semena, kao i morfometrijskih parametara sadnica (visina i prečnik u korenovom vratu) koje su proizvedene iz tog semena. U okviru ovog rada izvršeno je blizu 11 000 merenja. Analiza dobijenih vrednosti je urađena u programskom paketu Statistica. Komparativnom analizom dobijenih rezultata u proučavanju varijabilnosti morfometrijskih karakteristika šišarica, semena i sadnica može se zaključiti da postoji značajna međupopulaciona varijabilnost koja je u direktnoj zavisnosti od vrste analiziranog svojstva. Ovom analizom proverena je međusobna bliskost ili udaljenost po pitanju analiziranih svojstava, pri čemu je došlo do značajne diferencijacije populacija. Dobijeni rezultati predstavljeni u ovom radu, daju doprinos boljem razumevanju značajnosti analiziranih svojstava na diferencijaciju populacija, dajući preliminarno upoznavanje genetičkog varijabiliteta proučavanih populacija.

The ability of random amplified polymorphic DNA (RAPD) to distinguish among Scots pine populations from Serbia was evaluated. Sixteen arbitrary 10-mer primers employed in the analysis produced 54 fragments of which 21 were polymorphic (38.89%). Certain rare and genotype-specific bands were identified which could be effectively used to distinguish between the populations. Polymorphism in RAPD markers among P. sylvestris populations was high and sufficient to distinguish each of the populations. The results obtained suggest that RAPD markers are valuable for the genetic divergence estimation in Pinus sylvestris and for the study of divergence among populations.

Genetic markers, from morphological to molecular, in function with early indicators of tolerance toward drought, have been an object of research and scientific papers for many years. It starts with the hypothesis that seedlings produced from seeds that were collected from population of extremely different site conditions, on the level of open pollinated families, will have different results concerning drought tolerance. By tracking the dynamics of germination and morphological parameters of saplings, we are researching the interdependence of these parameters with the survival and growth of two-year-old seedlings in conditions where there is a lack of water. Austrian Pine seeds were collected from forty trees, distributed over five provenances on the Balkan Peninsula. Within each provenance a group is assigned to an extremely harsh and dry habitat, while also another group is assigned to prosperous (the most productive) habitat. The analysis of the twenty-one-day-old seedlings (saplings) is performed in the laboratory, while the tolerance test of the two-year-old seedlings is performed in the field. Seedlings that are exposed to conditions in which there is lack of water, have the coefficient of water formation evaluation 22.59 times bigger than sandy-clay soil with fraction of sand bigger than 60 percent. The results show significant and positive correlation between some parameters of saplings and the dynamics of growth (high increments) of the seedlings in drought, but no correlation with the survival of the seedlings.

This paper presents the results of studies on protein polymorphism in seeds of Scots pine (Pinus sylvestris L.) and Austrian pine (Pinus nigra Arn.) as the most important economic species of the genus Pinus in Serbia. Polymorphism of protein markers was determined in selected genotypes originating from seven populations (Scots pine) and six populations (Austrian pine). Analysis of protein markers was performed using two statistical methods, NTSYS and correspondence analysis. Both methods give the same arrangement of the analyzed populations, whereby, because of a different view of genetic distances, they can and should be combined, enabling easier and more precise understanding of mutual relationships of the observation units. U radu su prikazani rezultati proučavanja polimorfizma proteina u semenu belog (Pinus sylvestris L.) i crnog bora (Pinus nigra Arn.) kao najvažnijih ekonomskih vrsta iz roda Pinus u Srbiji. Polimorfizam proteinskih markera utvrđen je u odabranim genotipovima poreklom iz sedam populacija (beli bor) i šest populacija (crni bor). Analiza proteinskih markera vršena je upotrebom dva statistička metoda, NTSYS i korespodencijalna analiza. Dobijeni rezultati upotrebom različitih statističkih metoda (NTSYS i korespodencionalna analiza) u analizi proteinskih markera, upućujući na upotrebu oba metoda u sličnim istraživanjima, kao kompatibilnih. Grafikoni obe metode se karakterišu istim rasporedom analiziranih populacija, pri čemu se usled različitog prikaza trebaju kombinovati, što omogućuje lakše i preciznije sagledavanje međusobnih odnosa jedinica posmatranja. Takođe, dobijeni rezultati u ovom radu ukazuju na: · Postojanje značajne genetičke varijabilnosti populacija belog i crnog bora. · Snažan uticaj geografske distance i izolovanosti populacija na genetičku izdiferenciranost. Ujedno, rezultati istraživanja pružaju osnovu za bliže upoznavanje veoma varijabilne i specifične unutarvrsne genetičke strukture belog i crnog bora u Srbiji, što predstavlja polazno sredstvo u planiranju procesa konzervacija i oplemenjivanja vrsta.

Nitrogen content in the needles of twenty Douglas-fir provenances, originating from different sites within the native range of the species in the USA, was studied in a Douglas-fir provenance test established at the montane beech site on acid brown soil. Based on the variability of nitrogen content in the needles, the intensity and dynamics of the physiological processes of Douglas-fir mineral nutrition were analyzed as the indicators of Douglas-fir adaptive potential to the sites in Serbia. All the trees of the study provenances were of the same age and grown under the same site and population conditions. The quantities of nitrogen absorbed in Douglas-fir needles were correlated with the geographical characteristics of the native sites of the observed provenances. The differences in nitrogen content in Douglas-fir needles point out the variability in the intensity of the physiological processes in the genotypes of the different provenances. Since the study Douglas-fir trees are cultivated on relatively small areas, in more or less equal general conditions, it can be concluded that the parameters of mineral nutrition depend on the genotypes constituting the gene pool of the study Douglas-fir provenances.

The regionalization of forest tree populations was researched on an example of beech, as the species with the largest range and the widest ecological amplitude in Serbia. The implementation of Monmonier's algorithm of maximum differences to analyze the spatial distances and the matrix of genetic distances generated by RAPD markers produced different results, depending on the method of addressing the genetic distances, so that data processing should be planned in accordance with the number of samples and their geographic location. The analysis is simple and enables a good visualization of genetic variability barriers which, in combination with the data on the distribution and the geographic barriers, can be utilized for recommending the transfer of forest tree reproductive material. U radu je istražena mogućnost određivanja granica regiona populacija šumskog drveća, u cilju davanja preporuka za transfer reproduktivnog materijala, na primeru bukve. Na osnovu podataka iz Nacionalne inventure šuma dobijena je rasprostranjenost bukve u Srbiji sa rezolucijom 4h4 km. Na osnovu ovako dobijene karte areala, odabrane su oblasti koje će na najrelevantniji način predstavljati bukvu u Srbiji. U okviru ovog istraživanja, ispitano je 27 populacija, koje relativno ravnomerno pokrivaju prostornu i ekološku distribuciju populacija bukve. Analiza primenom RAPD markera, urađena je sa 28 prajmera. Ukupno su dobijene 82 trake. Za vizualizaciju onih podataka koji su sadržani u matrici genetičkih podataka, putem crtanja granica na geografskoj karti, korišćen je Monmonijeov algoritam u programu AIS. Prikazani su rezultati tri načina pripreme genetičkih distanci za analizu, sa zadatim brojem od 5 barijera za detekciju. Rezultati korišćenja sirovih genetičkih distanci pokazuju najveći broj segmenata (regiona), što nagoveštava malu prostornu autokorelaciju. Rezultati korišćenja genetičkih distanci ispravljenih na osnovu geografskih distanci pokazuju nešto manji broj segmenata (regiona), što ukazuje na veću preciznost dobijenu ovakvom pripremom genetičkih distanci za relativno mali broj uzoraka koji su prostorno udaljeni. Rezultati korišćenja ostataka genetičkih distanci pokazuju najmanji broj segmenata (regiona), što ukazuje na veliku snagu ovakve pripreme genetičkih distanci u slučajevima slabo izražene prostorne autokorelacije. Ovim pristupom, najverovatnije je omogućena i najtačnija vizualizacija genetičkog diverziteta. Analiza je jednostavna i omogućuje dobru vizualizaciju barijera genetičke varijabilnosti, što se u kombinaciji sa poznavanjem areala i geografskih barijera, može uspešno iskoristiti za davanje preporuka za transfer reproduktivnog materijala šumskog drveća. Vizualizacija se može dodatno poboljšati korišćenjem rezultata ove analize za crtanje karata u nekom od široko korišćenih programa GIS-a, i njihovim preklapanjem sa kartama fizičkog reljefa i drugim tematskim kartama.

This paper presents the concepts applied in the gene pool conservation and tree improvement in Serbia. Gene pool conservation of tree species in Serbia includes a series of activities aiming at the sustainability and protection of genetic and species variability. This implies the investigation of genetic resources and their identification through the research of the genetic structure and the breeding system of individual species. Paper also includes the study of intra- and inter-population variability in experiments - provenance tests, progeny tests, half- and full-sib lines, etc. The increased use of the genetic potential in tree improvement in Serbia should be intensified by the following activities: improvement of production of normal forest seed, application of the concept of new selections directed primarily to the improvement of only one character, because in that case the result would be certain, establishment and management of seed orchards as specialized plantations for long-term production of genetically good-quality forest seeds, and the shortening of the improvement process by introducing new techniques and methods (molecular markers, somaclonal variation, genetic engineering, protoplast fusion, micropropagation, etc.).

The paper reviews the study results of the use of molecular markers in coniferous tree species improvement. The results are based on presentation of the experience in the application of biochemical and molecular analyses at the level of the selected populations and individuals from different provenances of coniferous tree species. Many studies performed during the last years demonstrated the usefulness of neutral molecular markers in the field of conservation and population genetics of conifers, in particular to understand the importance of migration patterns in shaping current genetic and geographic diversity and to measure important parameters such as effective population size, past bottlenecks and gene flow. This is relevant to design conservation strategies but is of little value to understand the adaptability patterns. In the specific field of the conservation genetics, molecular markers can be extremely useful in both ex situ and in situ gene pool conservation of coniferous trees. U radu je dat pregled rezultata primene molekularnih markera pri oplemenjivanju četinarskih vrsta drveća. Prezentovani rezultati su dobijeni primenom biohemijskih i molekularnih markera u analizama koje su sprovedene na nivou odabranih populacija i individua različitih provenijencija četinarskih vrsta drveća. Brojna istraživanja sprovedena poslednjih godina potvrdila su opravdanost primene molekularnih markera u konzervacionoj i populacionoj genetici četinara, posebno pri tumačenju značaja pravaca rekolonizacije u formiranju genetskog i geografskog diverzitata, kao i za utvrđivanje značaja uticaja veličine populacije na fluktaciju gena. Dobijeni rezultati su od značaja za izradu strategije konzervacije, ali su nedovoljni za potpuno razumevanje modela adaptacije. Na polju konzervacione genetike molekularni markeri imaju poseban značaja u aktivnostima pri ex situ i in situ zaštiti i očuvanju genofonda vrsta četinara.

The occurrence of Austrian pine over large areas attacked by erosion processes or on completely degraded and denuded areas on which it produces excellent results, classifies it among the most important economic species in forestry. The aim of present research is to study intra- and inter-population genetic variation in Austrian pine by the application of biochemical markers. A better knowledge of the genetic potential of Austrian pine populations will enhance the production of seed and planting material, and in this way also the success of a forestation and the establishment of Austrian pine specific-purpose plantations. The polymorphism of protein markers was determined based on the selected genotypes originating from six populations (seed stands), which actually included all Austrian pine populations in Serbia. Based on the derived electrophoregram, qualitative and quantitative differences (number and pattern) in protein fractions were identified and the seed protein profile was constructed for each tree, as well as for each of the six study populations. This showed the 'conservativeness' of some polypeptides, i.e. the presence in all analyzed genotypes. On the other hand, some protein fractions were variable at the population level, and some were variable depending on the population. Based on the electrophoregram, the coefficient of genetic similarity/distance was calculated by comparing the band numbers and patterns. Cluster analysis dendrograms were also constructed. The degree of genetic variation among the provenances was higher than the variation within the provenances. There was also a high genetic variation in seed proteins within the analyzed populations. Javljanje crnog bora na velikim površinama zahvaćenim erozionim procesima, ili potpuno degradiranim, ogoljenim površinama na kojima daje odlične rezultate, svrstavaju ga u najvažnije ekonomske vrste korišćene u šumarstvu. Cilj ovih istraživanja je bilo ispitivanje unutar i među populacijske genetičke varijabilnost crnog bora primenom biohemijskih markera. Bolje upoznavanje genetskog potencijala populacija crnog bora omogućiće poboljšanje proizvodnje semena i sadnog materijala, a time i uspeh prilikom pošumljavanja i podizanja namenskih kultura ovom vrstom. Polimorfizam proteinskih markera utvrđen je na osnovu odabranih genotipova poreklom iz šest populacija (semenskih sastojina) čime su obuhvaćene sve populacije crnog bora u Srbiji. Na osnovu dobijenih elektroforegrama utvrđene su kvalitativne i kvantitativne razlike (broj i raspored) proteinskih frakcija i određen je proteinski profil semena za svako stablo kao i za svaku od 6 ispitivanih populacija ponaosob. Tom prilikom je zapažena 'konzervativnost' pojedinih polipeptida, tj. prisustvo u svim analiziranim genotipovima. S druge strane utvrđene su proteinske frakcije koje su varijabilne na nivou populacija, kao i one čija varijabilnost varira u zavisnosti od populacija. Na osnovu dobijenih elektroforegrama je izračunat koeficijent genetičke sličnosti, odnosno udaljenosti, upoređivanjem broja i rasporeda traka i urađeni su dendogrami klaster analize. Utvrđen je veći stepen genetskog variranja između provenijencija nego unutar njih. Takođe je utvrđena velika genetska varijabilnost proteina semena unutar analiziranih populacija.

Knowledge about spatial distribution of genetic diversity is very important for foresters in order to make right decisions during establishing of management plans for conservation, afforestation or reforestation. Advanced molecular technologies provide us with efficiently measured genetic information's which can be analyzed powerful statistical tools. Landscape Shape Interpolation analysis was applied on protein based marker data sets from six natural populations of Balkan beech. Results indicate existence of three genetically distinct groups: 1) Djerdap, Kopaonik, Zubin potok and Ivanjica; 2) Bor and 3) Pirot. These results were compared with results of UPGMA clustering of sampled population based on NEI original distances, Principal Coordinate Analysis and Monmonier's Maximum Difference Algorithm Analysis. Landscape Shape Interpolation analysis represent a powerful tool in spatial genetic diversity research. Combining of Landscape Shape Interpolation analysis results with digitalized maps of investigated area in some of numerous GIS applications will for certainly improve visualization of results and provide better understanding of causal factors of genetic diversity. Poznavanje prostorne distribucije genetičkog diverziteta je veoma važno za šumare, u cilju donošenja odgovarajućih odluka prilikom pravljenja planova gazdovanja u cilju konzervacije, pošumljavanja ili melioracije. Napredne molekularne tehnologije sa velikom efikasnošću obezbeđuju genetičke podatke koji se mogu analizirati moćnim statističkim alatima. 'Landscape Shape Interpolation' je primenjena na podacima o proteinskim markerima dobijenim iz šest prirodnih populacija bukve u Srbiji. Rezultati ukazuju postojanje tri genetički udaljene grupe: 1) Đerdap, Kopaonik, Zubin potok and Ivanjica; 2) Bor and 3) Pirot. Rezultati pejzažne interpolacije su upoređeni sa rezultatima UPMGA klasterovanja ispitivanih populacija na osnovu NEI originalnih distanci, analize principijalnih koordinata (PCooA) i analize Monmonijerovog algoritma maksimalnih razlika. Analiza primenom analize 'Landscape Shape Interpolation' predstavlja moćan alat u istraživanjima prostorne distribucije genetičkog diverziteta. Kombinovanje rezultata ove analize sa digitalizovanim kartama ispitivanog područja, u nekoj od brojnih GIS aplikacija, svakako će unaprediti vizualizaciju rezultata I omogućiti bolje razumevanje uzročnih faktora genetičkog diverziteta.

A precondition necessary for creation and selection of genotypes tolerant of stress conditions is a study of physiological, biochemical and molecular bases of their adaptive reaction to stress. The study includes 40 lines of free pollination originating from 5 provenances: Sutjeska, Višegrad, Tara, Teslić and Durmitor (B&H, Serbia and Montenegro). Two populations were selected from each provenance, i.e.: 5 lines of free pollination represent the population growing on the cliffs and 3 lines of free pollination represent the population growing at the best site of Austrian pine. Specific characteristics of the studied provenances, populations, and free pollination lines were confirmed by the analyses in the salt-soluble proteins. The identical protein composition was proved in a small number of cases in the replicates of the same free pollination line, which indicates a high intra-line variability, which can be the result of the effect of father, as well as of heterozygosity of mother trees. The analyses of protein composition of seed showed considerable differences at provenance level. Inter-line, population and provenance differences, and also, the interaction between the origin and drought factor, were recorded for 9-day-old seedlings germinated in induced drought conditions and in normal conditions. Preduslov za stvaranje i selekciju tolerantnih genotipova na stresne uslove je proučavanje fiziološke, biohemijske i molekularne osnove njihove adaptivne reakcije na stres. Istraživanjima je obuhvaćeno 40 linija crnog bora slobodnog oprašivanja koje potiču iz 5 provenijencija: Sutjeska, Višegrad, Tara, Teslić i Durmitor (BiH, Srbije i Crna Gora). U svakoj provenijenciji izdvojene su dvije populacije i to: 5 linija slobodnog oprašivanja predstavlja populaciju sa stijena i 3 linije slobodnog oprašivanja populaciju na najboljem staništu crnog bora. Specifičnost ispitivanih provenijencija, populacija, kao i linija slobodnog oprašivanja dokazana je putem analiza u solima rastvorljivih proteina. Identičan proteinski sastav u ponavljanjima iste linije slobodnog oprašivanja je dokazan u malom broju slučajeva, što govori u prilog velike unutarlinijske varijabilnosti koja može biti posledica uticaja oca, kao i heterozigotnosti materinskih stabala. U analizama proteinskog sastava sjemena konstatovane su najznačajnije razlike na nivou provenijencija. Kod klijavaca starih 9 dana, isklijalih u uslovima indukovane suše i u standardnim uslovima, utvrđene su međulinijske, populacione i provenijenične razlike, kao i značajne interakcije porekla i stresnog faktora suše.

Enzyme activity of peroxidases of total proteins and heavy metal contents were studied in the needles of eight different half-sib lines of Austrian pine. The samples were taken from a fourteen-year-old seedling seed orchard on Jelova Gora (near Uzice). The results of this study show the pronounced variability of the concentration of total proteins, heavy metal concentration and enzyme activity of peroxidases in the study Austrian pine half-sib lines. This infers that proteins have different levels of expression in individual Austrian pine lines. Also the enzyme of peroxidases shows different activity depending on the genetic constitution of the trees of the analysed half-sib lines, because based on the seed orchard size and the planting pattern, it can be assumed that the effect of external factors is reduced to a minimum. The peroxidases present as soluble in the apoplast or with covalent bond to cell wall, have an important role in lignification, suberisation, healing of injuries, defence against pathogens and atmospheric pollutants.

Mutations include the changes of the inherited material and they occur naturally, but very rarely. This paper presents the spontaneous and induced mutations, their frequency of occurrence and applicability for the needs of plant production in forestry. The initial material includes the trees and shrubs of Serbia, and the methods are the comparative morpho-physiological analysis, ionising radiation and chemical half-sib tests Spontaneous mutations in our country have been recorded more frequently since the sixties and the study of intra-variability of trees and shrubs in Serbia has been intensified. They include the changes of growth habit, character of increment, abnormalities in the structure of vegetative and generative organs. By selection and vegetative propagation, numerous ornamental tree and shrub varieties have been synthesised over a more or less long period. After the discovery of the vigour of triploid mutants trees, their mass production has been elaborated: by crossing triploid and diploid trees By the treatment of the reproductive material by ionising radiation (UV, gamma rays, terminal neutrons), and chemical materials, the frequency of mutations increased drastically, especially with higher doses up to 100% in the treated organisms. The mutants have, as a rule, reduced growth elements, reduced adaptation, and when selected and propagated vegetatively, they ensure a rich initial material for the synthesis of numerous ornamental cultivars of trees and shrubs. The method of radiation breeding is the most promising for the improvement of ornamental plants, while mass production of triploid mutants is the only method used in the improvement of forest trees.