Factors affecting pollen dynamics and its importance to pollen contamination: a review

1991 ◽  
Vol 21 (8) ◽  
pp. 1155-1170 ◽  
Author(s):  
F. Di-Giovanni ◽  
P. G. Kevan
Keyword(s):  
Gene Flow ◽  
Pollen Dispersal ◽  
Past Research ◽  
Seed Orchard ◽  
Dispersal Pattern ◽  
Seed Orchards ◽  
Factors Affecting ◽  
Pollen Contamination ◽  
Modelling Techniques ◽  
Natural Stands

Pollen contamination causes major losses to genetic improvement from selection and breeding of "plus" trees in conifer seed orchards. Genetic losses arise by the influx of "wild" conspecific pollen into seed orchards and its deleterious fertilization of superior genetic lines. This review firstly addresses the basis of the problem: pollen, conifer reproduction, and the concept of seed orchard management, especially in regard to reduction of contamination. Secondly, the physical processes of pollen liberation, dispersal, and deposition are described, and examples of previous studies illuminating these phenomena given. Thirdly, past research on measuring pollen dispersal in natural stands and seed orchards in discussed in the light of modelling techniques used to predict these types of dispersal pattern. Work on the other facets of contamination measurement, gene-flow studies, are listed. It is concluded that a detailed study that combines both the physical and gene-flow aspects of pollen dispersal should be initiated to compare and contrast the two methods, and that attempts to model pollen contamination should be sought.

Field performance and early test results of offspring from two Norway spruce seed orchards containing clones transferred to warmer climates

2007 ◽  
Vol 37 (3) ◽  
pp. 515-522 ◽  
Author(s):  
Tore Skrøppa ◽  
Ketil Kohmann ◽  
Øystein Johnsen ◽  
Arne Steffenrem ◽  
Øyvind M. Edvardsen
Keyword(s):  
Norway Spruce ◽  
Field Performance ◽  
Seed Orchard ◽  
Field Trials ◽  
Climatic Conditions ◽  
Test Results ◽  
Seed Orchards ◽  
Low Altitude ◽  
Natural Stands ◽  
Seed Crops

We present results from early tests and field trials of offspring from two Norway spruce ( Picea abies (L.) Karst.) seed orchards containing clones that have been transferred from high altitudes to sea level and from northern to southern latitudes. Seedlings from seeds produced in the low-altitude seed orchard developed frost hardiness later at the end of the growth season, flushed later in field trials, and grew taller than seedlings from seeds produced in natural stands. They had the lowest mortality rate and the lowest frequency of injuries in the field trials. Similar results were observed in seedlings from seeds produced in the southern seed orchard. We found no adverse effects of the changed growth rhythm. Seedlings from two seed crops in the southern orchard, produced in years with a warm and a cold summer, had different annual growth rhythms. The results are explained mainly by the effects of the climatic conditions during the reproductive phase. Seed crops from different years in the same seed orchard may produce seedlings that perform as if they were from different provenances. It is argued that the effects of the climatic conditions during seed production must contribute to the variation among provenances of Norway spruce.

scholarly journals Genetic Gain and Diversity of Orchard Crops Under Alternative Management Options in a Clonal Seed Orchard of Pinus thunbergii

2005 ◽  
Vol 54 (1-6) ◽  
pp. 93-96 ◽  
Author(s):  
Kyu-Suk Kang ◽  
D. Lindgren ◽  
T. J. Mullin ◽  
W.-Y. Choi ◽  
S.-U. Han
Keyword(s):  
Gene Flow ◽  
Genetic Gain ◽  
Seed Orchard ◽  
Pinus Thunbergii ◽  
Management Options ◽  
Pollen Contamination ◽  
Clonal Seed Orchard ◽  
Selective Harvest ◽  
Status Number ◽  
Seed Crops

Abstract Genetic gain and diversity, expressed by status number, of seed crops from a clonal seed orchard of Pinus thunbergii were estimated considering selection, fertility variation and pollen contamination, and compared for different management alternatives (selective harvest, genetic thinning and combination of both options). Management variables included the proportion of clones left after selective harvest and/or genetic thinning. The impact on genetic gain and diversity of seed crops was quantified as a function of the quantity and quality of gene flow from outside the seed orchard. Genetic gain varied with the proportion of selected or thinned clones. Genetic thinning by means of truncation selection of clones resulted in a large decrease in status number, which was accompanied by greater genetic gain than achieved by selective harvest alone. As expected, gene flow from outside the seed orchard greatly increased status number of the seed crop at higher rates of pollen contamination under all management options. The formulae and results of the present study could be used for identifying favorable selection intensity and alternatives for orchard management.

Mating system and pollen contamination in a Douglas-fir clone bank

1986 ◽  
Vol 16 (6) ◽  
pp. 1314-1319 ◽  
Author(s):  
Willi Fast ◽  
Bruce P. Dancik ◽  
Ralph C. Bower
Keyword(s):  
Mating System ◽  
Seed Orchard ◽  
Douglas Fir ◽  
Pollen Contamination ◽  
Outcrossing Rates ◽  
Natural Stands

Pollen contamination and mating system of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) clone banks used as an interim seed orchard near Nanaimo, B.C., were estimated. Pollen contamination (m) from surrounding clone banks and natural stands ranged from 0.44 to 0.89. Overall contamination over 2 years was estimated to be 0.65. Pollen contamination varied significantly over 2 pollination years. Multilocus outcrossing rates (t) of four clone banks over 2 years ranged from 0.51 to 1.09, with an unweighted mean outcrossing estimate of 0.72. Outcrossing varied significantly among clone banks and pollination years. An excess of homozygotes suggests that these seed may be inbred. Although pollen contamination and inbreeding may be a problem in these clone banks, the seed may still be useful operationally.

Variation of paternal contribution in a seed orchard of Cryptomeria japonica determined using microsatellite markers

2004 ◽  
Vol 34 (8) ◽  
pp. 1683-1690 ◽  
Author(s):  
Yoshinari Moriguchi ◽  
Hideaki Taira ◽  
Naoki Tani ◽  
Yoshihiko Tsumura
Keyword(s):  
Microsatellite Markers ◽  
Cryptomeria Japonica ◽  
Pollen Dispersal ◽  
Seed Orchard ◽  
Null Alleles ◽  
Contamination Rate ◽  
Seed Crop ◽  
Pollen Contamination ◽  
Self Fertilization

We investigated gene flow and pollen contamination in a seed orchard of Cryptomeria japonica D. Don using six microsatellite markers. The quality of a seed crop is determined by many factors, including the rate of pollen contamination from outside sources, degree of self-fertilization, and equality of the clones as pollen donors. The surveyed seed orchard consisted of 62 clones and a total of 360 ramets. The seeds from 12 mother trees in the seed orchard were investigated using six highly polymorphic loci with high multipaternity exclusion probability (0.999). The estimated average pollen contamination rate was high at 47.78% (±4.12%), and the clonal self-fertilization rate was 2.22% (±0.94%) when we assumed that null alleles were present. The high pollen contamination rate could dramatically reduce the quality of the seed crop. The contamination rate differed from tree to tree, but the differences were not related to the location of each individual. The levels of contribution as pollen donors differed significantly amongst clones in the seed orchard. Differences in flowering phenology and relative pollen fecundity may be responsible for the differences in paternal contributions. The effective distance of pollen dispersal in this C. japonica seed orchard seemed to be greater than previously estimated.

scholarly journals Clonal variation in phenological synchronization and cone production in a Pinus patula seed orchard

2020 ◽  
Vol 69 (1) ◽  
pp. 130-138
Author(s):  
Liliana Muñoz-Gutiérrez ◽  
J. Jesús Vargas-Hernández ◽  
Javier López-Upton ◽  
Carlos Ramírez-Herrera ◽  
Marcos Jiménez-Casas
Keyword(s):  
Pollen Dispersal ◽  
Seed Orchard ◽  
Clonal Variation ◽  
Pinus Patula ◽  
First Year ◽  
Effective Population ◽  
Cone Production ◽  
Pollen Release ◽  
Natural Stands ◽  
Male Strobili

Abstract Synchronization between female receptiveness and pollen dispersal, and fecundity of clones influence effective population size and genetic diversity of germplasm produced in seed orchards. Our objective was to determine clonal variation in phenological synchronization and in cone production in a Pinus patula seed orchard. Two-year phenology data of female and male strobili from a sample of 31 clones, and of male strobili in trees from neighboring natural stands of the same species were used. Synchronization indices between female receptiveness and pollen release of the same clone (O̅iP̅i), of other clones (O̅i P̅j), and of natural stands (O̅i P̅NS) were calculated for each clone and averaged per precocity group (early, intermediate, and late). Genetic parameters for cone production of clones during three consecutive cone harvests were estimated, as was their relationship to precocity and synchronization index O̅i P̅NS. Cone production showed a broad variation among clones and between years, with strong genetic control (H2c ≥ 0.80) and stable (rB ≥ 0.79) between yeas. There was wide clonal variation in synchronization indices, but no significant variation was found in most cases among precocity groups, neither were they consistent between years. Negative correlations [rp = -0.37 and -0.40 (P < 0.05)] in cone production per clone in two years with the O̅i P̅NS index in the first year, indicated that the most prolific clones had lower synchronization with pollen release in natural stands in the orchard’s vicinity, and thus less risk of genetic contamination.

Performance of Japanese and Hybrid Larch Progenies in Pennsylvania

1994 ◽  
Vol 11 (2) ◽  
pp. 53-57 ◽  
Author(s):  
James J. Zaczek ◽  
Kim C. Steiner ◽  
R. D. Shipman
Keyword(s):  
Growth Rate ◽  
Seed Orchard ◽  
Japanese Larch ◽  
The Other ◽  
High Survival ◽  
Seed Orchards ◽  
Plus Tree ◽  
Progeny Tests ◽  
Natural Stands ◽  
Better Than

Abstract Two series of larch progeny tests were established at three locations in Pennsylvania in the spring of 1984. The Penn Orchard series contained progenies of 24 "plus-tree" Japanese larch clones growing in a seed orchard in Pennsylvania, two production seedlots of Japanese larch, and two lots of Japanese x European larch hybrids. The Westvaco test contained 5 hybrid seedlots and 15 seedlots of Japanese larch originating from 9 seed orchards (including Penn "A" Orchard), 5 plantations, and one natural stand. After 7 yr, only one site was clearly ideal for Japanese larch, having produced both rapid growth (0.83 and 0.99 m/yr) and high survival. Survival or growth was considerably lower at the other two sites, probably because of both seasonally excessive and deficient soil moisture. Hybrid lots were significantly shorter than others at the best site; they tended to survive significantly better than Japanese larch at the other two sites, but they did not necessarily grow taller. Progenies from seed orchards were not significantly faster growing than those from plantations or natural stands (Westvaco test); and progenies from select trees in the Penn Orchard test were not significantly faster growing than production lots. Although genetic effects on 7 yr height were significant in most individual plantations, few seedlots could be statistically distinguished as superior or inferior in growth rate. Seedlot pedigree had much less influence on growth rate or survival than did choice of site. North. J. Appl. For. 11(2):53-57.

Inhibiting Factors of Cost Performance in UAE Construction Projects

2020 ◽  
Vol 11 (2) ◽  
Author(s):  
Ahmed Salem Ahmed Marey Alhammadi ◽  
◽  
Aftab Hameed Memon ◽  
Keyword(s):  
Construction Industry ◽  
Construction Projects ◽  
Past Research ◽  
Cost Overrun ◽  
Index Method ◽  
Cost Performance ◽  
Factors Affecting ◽  
Inhibiting Factors ◽  
Critical Problems ◽  
Structured Questionnaire

UAE construction industry frequently faces poor cost performance which commonly known as cost overrun problem. This problem is resulted from several factors and it is important to identify these cost overrun factors in order to avoid and minimize it. Hence, this paper focused on determined the relevancy of factors affecting cost performance in construction projects of UAE. Through a review of past research works conducted globally, 27 factors of cost overrun were listed and used for developing a structured questionnaire. A survey was conducted with 33 practitioners from client, consultant and contractors organizations involved in handling construction projects in UAE. The respondents were requested to state their perception regarding the relevancy of each of the factors that was perceived in context with cost overrun issue using 5-points Likert scale. The responses were analysed using average index method and the results found that all the 27 factors are relevant with construction industry of UAE in causing cost overrun. These factors can be used for further investigation to uncover critical problems of cost overrun.

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