Black locust (Robinia pseudoacada L.) clonal seed orchards in Hungary

Black locust （Robinia pseudoacacia L.） is one of the most important stand-forming tree species in Hungary and its impor- tance is increasing in many countries. The main aim of the discussed new selection programme is to identify black locust clones with good performance and good form for setting up clonal seed orchards. As a result of selection programme 16 new black locust clones have been improved. In spring 2002 a black locust seed orchard was established with the newly selected clones. About 40% of the plants can be considered to belong to the height growth rate class 1 and 2. Hungary was the first country where micropropagated black locust planting material was used for seed orchard establishment.

Study on Growth and Genetic Gains of Different Families in Eucalyptus urophylla Second Generation Seed Orchards

A second-generation seedling seed orchard including 32 open-pollinated families of Eucalyptus urophylla was built at Gaoyao City, Guangdong Province to examine the genetic performance of the orchard, which were selected from the superior trees in an improvement seed orchard. Compared to the characteristics of height, DBH, individual volume, stem form, branch and blossom quantities among different families at 22 months. The results indicate that: (1) The most superior families in individual volume and bl...

Branching and growth of plantings in fifth year of a seedling seed orchard of Masson pine (Pinus massoniana Lamb.)

The features of branching and growth studied included height, diameter at breast height (DBH), total number of branches, annual height growth, annual branch elongation in the year of elongating, annual branch number for four consecutive years, diameter of branches of different ages, and diameter of stem where branch-whorl originates. For features of total growth and overall branching, no significant differences were found between families, except for DBH. For annual features, no significant differences were found in annual stem height growth, annual branch elongation in the year of elongation and diameter of branches. In the last four years, differences in number of branches were not significant in the first two years but were significant in the last two year; differences in stem diameter where branch-whorls grow were significant for the four consecutive years. Trend of annual growth and branching features of families can be divided into three types as increasing type, stable type and fluctuating type. Most of families have an increasing type with respect of annual height growth and annual branch elongation, while most families belong to a fluctuating type with annual branch number. The results indicated that in the fifth year after planted in seedling seed orchard, differences between families were mostly insignificant. This result may have two main explanations: one is the growth rhyme in early ages of Masson pine, the other one is the complex paternal components to form the open-pollinated families. Family selection seemed to be not useful based on the result. It is suggested to select some of families in the nursery instead of to use all the families when establishing seedling seed orchards with open-pollinated families from plus-trees.

Phenological observations on Larix principis-rupprechtii Mayr. in primary seed orchard

Through 5 years of phenological observations on Larix principis-rupprechtii Mayr. in primary seed orchard and studies on population and individuals of clones, the annual periodic phenological laws were revealed and the annual phe-nological periodic table was drawn up. The correlation between various phenophases, the air temperature and active accumu-lated temperature were analyzed and expounded. The authors also analyzed the similarities and differences of phenophases among clonal individuals as well as the blooming properties of male and female flowers at the same time. This study could pro-vide theoretical reference for working out the production plan of improved varieties and other management measures in seed orchard of Larix principis-rupprechtii.

Evaluation of seed production in a first-generation seed orchard of Chinese pine (Pinus tabuliformis)

We evaluated seed production in a first-gener- ation orchard of Chinese pine （Pinus tabuliformis） during the crucial transition period from first generation to advanced generations. Clones varied significantly in all traits related to seed production. Repeatability of these traits ranged from 0 to 0.96. Seed production per ramet （SPPR）, seed producing index （SPI）, the number of relative female strobili （RFS）, the number of scales, and the num- ber of ineffective scales had comparatively high repeata- bility at 0.86, 0.87, 0.89, 0.96, and 0.91, respectively. Correlation analysis showed that SPPR was greatly influenced by RFS and by the number of full seeds per cone. Finally, we showed that SPI was the best predictor of the seed-producing ability of clones. Our findings will assist seed orchard managers in effectively predicting and improving seed production of Chinese pine seed orchards.

Options for converting a clone trial of Eucalyptus camaldulensis into a clonal seed orchard considering gain,fertility and effective clone number

We evaluated a clone trial comprised of 20 ramets each of 40 Eucalyptus camaldulensis clones for growth and fertility at 4 years of age. The clones differed significantly in growth with 65-100 % survival in 38 clones while two clones had low survival （40 and 10 %）. Fecundity was high and fertility variation low, as indicated by the sibling coefficient value （ψ = 1.4） with 55 % of clones contributing 80 % of the fruits. Thinning strategies were considered to convert the clone trial to a clonal seed orchard and enhance both gain and diversity in seed crop. When clones were selected based on growth without con- sidering fertility, truncation selection （to retain clones with higher DBH than the trial mean value） would give 8 % gain, but 59 % reduction in effective population size （Ne）. Gain and predicted diversity （Ne） was highest when ramets were selected in linear proportion to the breeding value of each clone. Mass selection with the same intercept （for DBH） as truncation selection would give a moderate 3 % gain, but over two times higher predicted Ne than trunca- tion selection. When fertility of retained trees was con- sidered after thinning, mass selection would yield 52 % effective contribution from the orchard trees compared to only 30 % contribution from truncation selection and linear thinning. Higher representation of superior clones in linear thinning and mass selection would lead to greater fertilityvariation and over 30 % reduction in effective clone number （Nc） from that predicted （Ne, assuming equal fer- tility among ramets） before thinning.

Does ash dieback affect the reproductive ecology of Fraxinus excelsior L.?

Forest tree species reproduction is a key factor in maintaining the genetic diversity of future generations and the stability of forest ecosystems.The ongoing ash dieback disease could affect the reproductive ecology of Fraxinus excelsior L.and have a major impact on the quantity and quality of pollen and seeds.In this study,we investigated pollen production and viability of pollen and seeds of ash trees with different health status from 2018 to 2022.Inflorescences were collected from 105 trees(pollen production),pollen from 125 trees(pollen viability),and seeds from 53 trees(seed quality)in two seed orchards and in one floodplain forest in southern Germany.Not all parameters were examined at every site every year.The average pollen production per tree was estimated at 471.2±647.9 billion pollen grains.In addition,we found that a high number of inflorescences did not equate to high pollen production per inflorescence.Pollen production of healthy and diseased trees did not differ significantly,although only 47%of severely diseased male trees(vs.72%for healthy trees)produced flowers.With regards to pollen viability,the TTC test showed an average viability of 73%±17%.Overall,there was a slight tendency for diseased trees to have less viable pollen.However,a significant difference could only be calculated for trees in the floodplain forest.The percentage of germinable seeds in 2018 was 38%in the floodplain forest and 57%in one of the seed orchards.The percentage of viable seeds(TTC test)ranged from 17 to 22%in the orchards in 2020.Non-viable seeds were usually heavily infested by insects.In general,seed quality was not significantly different between healthy and diseased trees.Our results indicate that ash dieback affects flower formation and pollen viability but not pollen production or seed quality.Nevertheless,the fact that hardly any flowering was observed,especially for trees that were seriously affected,suggests a negative effect of ash dieback on reproductive performance.Thus,severely diseased trees will transfer their genes to a smaller extent to the next generation.

Genetic analysis of growth and wood variations in Leucaena leucocephala (Lam.) de Wit.

We selected 28 populations of Leucaena leucocephala from different geographical locations in the states of Andhra Pradesh, Tamil Nadu and Orissa of India on the basis of height and girth at breast height （GBH）. We evaluated fiber length, optical density, wall thickness, vessel element length, vessel element diameter, specific gravity and lignin of these populations of L. leucocephala in different sites. Populations had significant variations for all growth, wood and paper parameters. Girth at breast height （GBH） and specific gravity were the most important pa- rameters for heritability and genetic gain, respectively. The minimum heritability was reported for vessel element length and genetic gain for fiber length. The populations were grouped into six clusters, cluster II had maximum number of populations （14） and clusters IV and VI had one population each. GBH contributed maximum of 34.39 % towards total divergence followed by specific gravity （14.02%）. An economic technique to produce quality seed by establishing seed orchards with genetically divergent parents was suggested. The hybridization among the populations selected from diverse clusters could produce greater heterosis needed for higher growth and suitable wood and paper manu- facturing parameters.

Assessment of genetic diversity in Dalbergia sissoo clones through RAPD profiling

We studied the genetic polymorphism among 29 clones of shisham （Dalbergia sissoo Roxb） belonging to different geographic regions using random amplified polymorphic DNA （RAPD） markers. Out of 30 primers used, only 20 primers generated polymorphism in amplified product. In total 232 bands were amplified with 20 primers, of which 192 （82%） were polymorphic with an average of 9.6 bands/primer. The resolving power （Rp） ranged from 2.14 （Primer 5） to 11.93 （Primer 4）. Primer 4 and Primer 3 possessed high Rp value. Polymorphism information content （PIC） ranged from 0.15 （Primer 5） to 0.37 （Primer 4）. Primer 4 amplified total 18 bands in 29 genotypes with PIC value of 0.37 hence; this set of primer was most informative. The similarity coefficient analysis revealed two clusters. The first cluster comprised of only 10 clones and the second major cluster comprised of 19 clones. The genetic similarity among 29 clones ranged from 25.86% （clone 10 and 235） to 100% （clone 19 and 59）, suggesting a wide genetic base in shisham clones.

Genetic divergence for growth and wood parameters in different clones of Dalbergia sissoo Roxb

The wood analysis for different parameters was carried out in a clonal seed orchard ofDalbergia sissoo Roxb. established during 1997 at Hoshiarpur, Punjab, India. Twelve clones with higher index value were subjected to Euclidean Cluster Analysis based on wood and growth parameters to group into seven clusters. Cluster I and II contained four and three clones, respectively, and remaining clusters bad just one clone each. Clone originated from Barielly, Uttar Pradesh of cluster VII was found to be the most divergent clone. Cluster II with three clones main- tained greater inter cluster distance with other clusters. The divergence analysis has confirmed that the clones planted in the clonal seed orchard are sufficiently divergent and seed harvested from the orchard would maintain high diversity.

Family Outcrossing Rates of Pinus caribaea Morelet var. caribaea in Seed Orchard and Natural Populations

Family outcrossing rates of Pinus caribaea var. caribaea populations that differed in origin and management were estimated by using isozyme markers. The family outcrossing rates were estimated by (1)fixing the probability of pollen gene frequency (p); (2) allowing pollen gene frequency to vary among families. The estimates of family outcrossing rates for all the populations varied widely among families (clones of the seed orchard), ranging from 0.39 to 2.0. The average family outcrossing rates of both m...

Research progress on genetic improvement of Betula platyphylla Suk.

Betula platyphylla Suk. is one of the most widely distributed species of Betula, the fourth most valuable timber species in north-eastern China and also a common tree species for landscaping. Over the past 30 years, effective progress has been made in genetic improvement and molecular breeding of B. platyphylla.There has been extensive research on breeding techniques,including the collection and conservation of B. platyphylla germplasm resources, provenance trials, intensive breeding techniques, crossbreeding and asexual propagation techniques, ploidy breeding and mutation breeding technology, genome sequencing, gene cloning, transgenic and molecular mechanisms of wood formation. A Betula germplasm resource collection has been established by collecting different provenances, and full-sib and half-sib families. In addition, the geographic variation patterns of B. platyphylla provenances have been revealed, and the provenance division and superior provenance selections made. B. platyphylla flowering and seeding have been improved through intensive breeding techniques. Interspecific hybridization, intraspecific hybridization and parallel crosses were made using fine parents, and B. platyphylla intensive seed orchards have been established. Systems of asexual propagation, including cuttings,grafting and tissue culture have been established. A B. platyphylla tetraploid was successfully constructed and a B. platyphylla triploid seed orchard established. The growth, wood property and resistance genes of B. platyphylla have been cloned. An efficient B. platyphylla transgenic system mediated by Agrobacterium tumefaciens was established, and genes encoding B. platyphylla insect resistance, drought resistance and salt tolerance, lignin synthesis, flowering, hormone transport and balance obtained. B. platyphylla molecular markers were developed and the high density B. platyphylla genetic map constructed. All this researchhas provided a model and data for the foundation of forest genetic improvement and applied research.