Eucalyptus Amplifolia and Corymbia Torelliana in the Southeastern USA: Genetic Improvement and Potential Uses

Eucalyptus amplifolia and Corymbia torelliana genetic improvement has been conducted in the lower southeastern USA by UF and collaborators since 1980. The collective accomplishments in genetic resources and potential commercial uses are summarized. For example, fast-growing, freeze-resilient E. amplifolia seeds are provided by 1st and 2nd generation seedling seed orchards (SSO) and a 2nd generation clonal seed orchard (CSO), while C. torelliana seed are available from 1st and 2nd generation SSOs. Breeding values (BV) have been developed for guiding the deployment of improved genotypes. Collaborative genetic improvement of these species is ongoing, including testing E. amplifolia in 11 countries and development of hybrid clones. Short Rotation Woody Crop (SRWC) systems may increase productivity and extend uses beyond conventional mulchwood to products such as medium density fiberboard (MDF), biochar, and energywood, while other possible applications include honey production, windbreaks, dendroremediation, and carbon sequestration. C. torelliana may be paired with E. grandis in two-row windbreaks to maximum windbreak effectiveness and may sequester as much carbon as E. grandis.

Progeny testing of Pinus sylvestris L. of seed orchard in different environmental conditions

Evaluation of the progeny test of plus trees of Scots pine - a necessary condition for determining the prospects the use of improved seeds in different environmental conditions. The paper presents the results of the study of the progeny test of groups of clones of plus trees of Scots pine selected according to certain characteristics in Northern Steppe and South Forest-Steppe of Ukraine. Analysis of results showed: a significant improvement in the growth rates of the all testing progenies of seed orchard in the better climatic and soil conditions of South Forest-Steppe between the ages of 3 and 10 years. At the same time 4 out of 5 studied progenies worsened their growth indicators relative to local control at the age of 3 to 26 years in less optimal climatic and soil conditions of Northern Steppe. The leader in the steppe conditions was the progeny of a fraction of three clones, which had the highest seed productivity. The selection of the fastest growing clones and the rejection of the slowest growing ones had a positive effect on the growth of progenies of seed orchards at both test points.

Mahogany (Swietenia macrophylla King.) as urban tree: tree growth and wood quality variation in a progeny test

Mahogany (Swietenia macrophylla) is a tree species widely planted not only for timber production but also as a shade tree in urban areas both on the side of the highway (green belt) and other green open areas. The objective of this study was to analyze the genetic variation of growth and wood quality of a mahogany progeny test at the Parung Panjang, Bogor, which will be converted into a seedling seed orchard for high quality seed production. The progeny test was established using a randomized complete block design involving 96 families originating from seven populations (land races) in Java Island, i.e., Cianjur, Sumedang, Tasikmalaya, Magelang, Gundih, Madiun, and Jember. The results showed that the family had a significant effect on all the growth and wood quality parameters. Individual and family heritability for all growth and wood quality traits were categorized into the high, i.e., 0.33 - 0.96 and 0.35 - 0.56, respectively. The selection simulation showed that the selection percentage of 44.68% (45 best families) gave the optimum genetic gain based on growth and wood quality traits.

Genetic diversity of Pericopsis mooniana from South Kalimantan based on Random Amplified Polymorphism DNA (RAPD) Markers

The genetic diversity and relationship of Pericopsis mooniana collected from Pulau Laut, South Kalimantan, was analyzed using RAPD markers. Currently, the natural distribution of P. mooniana in Pulau Laut no longer exists. Instead, PT Inhutani II, as the concession holder in the area, had collected the remaining P.mooniana and planted it in the seed orchard, arboretum, or around PT Inhutani’s mess/office. Forty-two samples from four locations: mess/residential house (3), seed orchard (33), arboretum (3), and PT Inhutani II Unit Stagen (3) were analyzed using seven RAPD primers. Our study showed that the total genetic diversity of all populations was low (He = 0.191 ± 0.013). P. mooniana collected from seed orchards had the highest diversity (He = 0.289 ± 0.021), while the lowest was from mess/residential houses (He = 0.134 ± 0.025). The genetic relationship data indicated the possibility that P. mooniana from mess/residential house, arboretum, and seed orchard may come from the same origin. These results can be used to support the development of ex-situ conservation plots to avoid inbreeding depression. At the same time, the genetic diversity will be helpful in its conservation and further utilization, such as establishing the plantations to reduce the pressure of the species in nature and provide valuable timber production in Indonesia.

Variation in Platycladus orientalis (Cupressaceae) Reproductive Output and Its Effect on Seed Orchard Crops’ Genetic Diversity

The genetic efficiency of seed orchards is crucial for determining seed crops’ genetic gain and diversity. Platycladus orientalis is a conifer tree of important ecological value in China. Here, we assessed the reproductive output (fertility) variation for 166 clones in a first-generation P. orientalis seed orchard over five years and across three years for each gender (female: 2017, 2018, and 2020 and male: 2017, 2019, and 2021). Fertility variation and genetic diversity parameters were estimated for each gender-year combination. The reproductive output (fertility) variation differed among years, provinces, clones nested within provinces, and ramets within clones. We observed asymmetry in the gender reproductive output and parental imbalance and determined their profound effects on the genetic diversity of these seed crops. The maleness index revealed the existence of female-biased or male-biased clones. When seeds from multiple individuals and years were blended, we found an increase in the effective number of parents (Np) and in genetic diversity (GD), and a reduced fertility variation (Ψ) in the seed orchard. When we set the effective number of parents (Np) to 30, the GD of the seed orchard could be maintained at more than 95%. Thus, achieving genetic diversity balance in seed production can be accomplished through monitoring the fertility variation of orchards and through the utilization of the thereby generated information for the advanced generation of seed orchards.

Genetic diversity of seeds from four German Douglas fir (Pseudotsuga menziesii) seed orchards

In Germany, Douglas fir (Pseudotsuga menziesii Franco) is seen as a valuable species for future cultivation in times of climate change. Local seed production in seed stands and seed orchards may secure that local adaptation is transferred to the next generation, but small population sizes could lower genetic diversity and thus future adaptability. Here we analyse the transfer of genetic diversity from parent to offspring generation in four older German seed orchards. We detected low pollen contamination rates due to high levels of spatial isolation. Even with a relatively low number of 40 clones, seed orchard design with randomized and repeated planting of clones led to low selfing rates, and despite uneven parental contributions, the number of successful parents and the level of genetic intermixture were high enough to allow the transfer of an adequate part of the genetic diversity to the next generation. Larger numbers, however, might be needed to reliably conserve the entire genetic diversity over succeeding generations. Conclusions on the establishment of future seed orchards and regarding areas requiring further research are drawn at the end of the paper.

Evaluation of Long-Term Shortleaf Pine Progeny Tests in the Ouachita and Ozark National Forests, USA

Between the late 1970s and the early 1990s, the USDA Forest Service installed 155 shortleaf pine (Pinus echinata Mill.) progeny tests in national forests across the Southern Region of the United States. Using control-pollinated crosses from the Mount Ida Seed Orchard, 84 of these progeny tests were established in the Ouachita and Ozark-St. Francis National Forests in Arkansas and Oklahoma. Each of these 84 test locations had, on average, 33 full-sibling families representing three local geographic seed sources (East Ouachita, West Ouachita, and Ozark). Though largely abandoned years ago, the progeny tests that remain provided an opportunity to determine if significant genetic and genetic × environment variance exists for performance traits (d.b.h., tree height, and survival) decades after installation. In 2018 and 2019, we remeasured d.b.h. and height and determined survival in 15 fully stocked progeny tests. Family variances were significant (p < 0.01) for both d.b.h. and height but not for survival (p > 0.05). Seed sources differed significantly (p < 0.05) for d.b.h., with more pronounced latitudinal differences. Additionally, we determined that individual tree and full-sibling family mean heritabilities were moderate (0.15 and 0.72, respectively, for d.b.h and 0.09 and 0.41, for height), suggesting relatively high genetic to environmental variation and good potential for genetic improvement. We also found that shortleaf pine families were broadly adapted in this region since family-by-test variances were non-significant (p > 0.05).

Advanced genebank management of genetic resources of European wild apple, Malus sylvestris, using genome-wide SNP array data

The Netherlands’ field genebank collection of European wild apple (Malus sylvestris), consisting of 115 accessions, was studied in order to determine whether duplicates and mistakes had been introduced, and to develop a strategy to optimize the planting design of the collection as a seed orchard. We used the apple 20K Infinium single nucleotide polymorphism (SNP) array, developed in M. domestica, for the first time for genotyping in M. sylvestris. We could readily detect the clonal copies and unexpected duplicates. Thirty-two M. sylvestris accessions (29%) showed a close genetic relationship (parent-child, full-sib, or half-sib) to another accession, which reflects the small effective population size of the in situ populations. Traces of introgression from M. domestica were only found in 7 individuals. This indicates that pollination preferentially took place among the M. sylvestris trees. We conclude that the collection can be considered as mainly pure M. sylvestris accessions. The results imply that it should be managed as one unit when used for seed production. A bias in allele frequencies in the seeds may be prevented by not harvesting all accessions with a close genetic relationship to the others in the seed orchard. We discuss the value of using the SNP array to elaborate the M. sylvestris genetic resources more in depth, including for phasing the markers in a subset of the accessions, as a first step towards genetic resources management at the level of haplotypes.