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  • 1
    Electronic Resource
    Electronic Resource
    Melbourne, Australia : Blackwell Science Asia Pty. Ltd.
    Austral ecology 26 (2001), S. 0 
    ISSN: 1442-9993
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The floral visitors of silky oak, Grevillea robusta A. Cunn. ex R.Br., their foraging behaviour and their effects on fruit-set were studied at Malava, western Kenya. Grevillea robusta is a popular tree for farm plantings in the eastern and central African highlands. Yield of seed has been disappointingly low in some areas and a lack of appropriate pollinators has been suggested as a possible cause. Investigations involved the monitoring of visitors on active inflorescences, assessment of the rewards available to potential pollinators, and exclusion experiments to establish the effects of various visitors on fruit-set. The flowers are visited mainly by birds and insects. The likely pollinators of G. robusta are sunbirds (Nectarinia amethystina, N. cyanolaema, N. olivacea, N. superba and N. venusta) and white-eyes (Zosterops kikuyuensis and Z. senegalensis). Very little aggressive behaviour between birds was recorded. No nocturnal pollinators were observed. Nectar was the major floral reward for pollinators, but is likely depleted by ants and honey bees, the foraging behaviour of which confirmed them to be nectar-robbers. These insects hardly ever touched stigmas during their visits. Eighty-nine per cent of bird visits were in the morning (07.00–10.00 hours) when nectar volume was highest. Inflorescences bagged to exclude birds set no fruits, and unmanipulated flowers and flowers bagged with self-pollen set no fruits, indicating a self-incompatibility mechanism. Control cross-pollinated flowers displayed greatly increased fruit-set (25.1%) compared with natural open-pollination (0.9%). All these findings confirm the importance of cross-pollen transfer to flowers and the necessity of pollinators for fruit-set. Effective seed production requires activity of pollinators for self-pollen removal and cross-pollen deposition. Seed production stands for G. robusta should be established where flowering is prolific and bird pollinators are abundant.
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  • 2
    ISSN: 1432-2242
    Keywords: Key words NESTUR ; Stem growth efficiency ; RAPD ; QTL ; Haploid megagametophyte
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  NESTUR (needle-to-stem unit rate) is a stem growth index of conifer seedlings that measures the efficiency of stemwood production per unit of needle growth, and is related to other seedling traits such as height, stem diameter, stem volume and needle volume. Quantitative trait loci (QTLs) affecting the expression of stem growth efficiency in radiata pine seedlings were investigated using a RAPD linkage map constructed from markers scored on haploid, megagametophytic DNA. Four putative QTLs were detected which accounted for 8.5–36.4% of the population variance. A search for evidence of epistasis, using both complete pairwise and conditional interactions, did not yield any statistically significant result. Over a 3-year period, seedlings with high-NESTUR marker alleles showed a superior growth performance of 17–40% for height, diameter and volume over those with low-NESTUR marker alleles.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 97 (1998), S. 1053-1061 
    ISSN: 1432-2242
    Keywords: Key words RAPD ; QTL ; Age effects ; Stem growth ; Linkage map ; Haploid megagametophyte
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Haploid megagametophytes from a full-sib cross of Pinus radiata were used to construct a genetic linkage map for radiata pine based on random amplified polymorphic DNA (RAPD) markers. The map, which was made from 222 markers, was used to carry out a QTL analysis of growth using measurements made on seedlings from which these megagametophytes were collected at an early germination stage. Trends in the expression of QTLs for stem diameter, volume and height were compared using measurements made at 5 months of age, and at 1, 2 and 3 years of age. None of the observed trends showed complete stability, i.e. none of the putative QTL positions detected at any one age was strongly expressed at all of the four stages of measurement. However, 45% of the trends showed partial stability, i.e. putative QTLs significant at one age were also detected at a subsequent age. Trends in QTL expression with age followed one of three patterns: (1) putative QTLs at some locations showed a gradual linear increase in influence from 5 months of age and were highest at 3 years of age; (2) QTLs detected at 5 months of age gradually became less significant with age; and (3) some putative QTLs showed a curvilinear increase in effect from 5 months of age, reaching their peak expression at 1 to 2 years, and sometimes were still detected at 3 years of age.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 95 (1997), S. 119-124 
    ISSN: 1432-2242
    Keywords: Key words Bulked segregant analysis ; Quantitative trait locus ; Epistasis ; Stem growth efficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Needle-to-stem unit rate (NESTUR) is a stem growth index of conifer seedlings that measures the efficiency of stemwood production per unit of foliage growth. The random amplified polymorphic DNA (RAPD) technique was applied to haploid DNA from the megagametophytes of a full-sib radiata pine cross to find markers linked to factors controlling the NESTUR trait. Using the bulked segregant analysis approach, 23 of 933 primers displayed putative linkage to factors controlling NESTUR. Based on the genotypic analysis of 174 individuals, two quantitative trait loci (QTLs) controlling NESTUR were identified at ANOVA P-levels of 0.01–0.001. The QTLs were identified by RAPD markers OPE-06450 and OPA-101200, which were linked to each other (r=7%), and UBC-333550, which was not linked to the other two. Linkage to components of NESTUR (increments in stem diameter and stem volume) was demonstrated for UBC-333550, while the others were not linked to NESTUR components.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Euphytica 21 (1972), S. 129-142 
    ISSN: 1573-5060
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Seasonal height and girth growth patterns of hybrids between Slash Pine (Pinus elliottii Engelm. var elliottii L. & D.) and Caribbean Pine (Pinus caribaea Mor. var hondurensis B. & G.) were compared with those of the parental species over one year at Beerwah Forest in southern coastal Queensland, Australia. The parental growth patterns differed markedly. Slash Pine had very vigorous early season growth, the rate then declined steadily through the later part of the season until the species entered winter dormancy. Caribbean Pine grew steadily throughout the year with late summer the most active period and winter the least. The hybrids combined the parental growth patterns with a consequent vigour advantage. Slash Pine showed a high degree of stem to stem synchronization of height growth in the early season, but much less in the later part, whilst height growth of Caribbean Pine was totally asynchronous. The hybrid was intermediate in stem to stem synchronization. The number of branch whorls produced by individual trees of Slash Pine on the main stem in the season 1965–1966 were found to be directly related to the length of the growing season for the tree concerned and also to the total height of the tree. Counts on trees at various centres in Queensland showed a decrease in branch whorl number per season with movement northwards suggesting a decrease in the length of the growing season of the species at lower latitudes. Possible physiological reasons for this are discussed.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Euphytica 19 (1970), S. 184-189 
    ISSN: 1573-5060
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Crossability values were calculated for (a) eight individual tree crosses betweenPinus elliottii Engelm. var.elliottii L. & D. andP. caribaea Mor. var.caribaea B. & G., (b) ten crosses betweenP. caribaea var.caribaea andP. caribaea var.hondurensis B. & G., and (c) twelve crosses betweenP. elliottii var.elliottii andP. caribaea var.hondurensis. Individual trees showed differences in ability to hybridize. Despite wide variation for each combination, the compatibility of the various combinations could be defined. It was high for (a), moderate for (b) and poor for (c). These results indicate the need for taxonomic review of theP. elliottii — P. caribaea species complex and suggest that hybridization within the complex might have economic value in Queensland forests.
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  • 7
    ISSN: 1573-5095
    Keywords: Tea tree oil ; genetic parameters ; combined index selection ; breeding strategy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Variation in oil yields from plantations and natural stands of Melaleuca alternifolia (Maiden and Betche) Cheel indicates considerable potential for improving plantation production through breeding. Some populations of the more widely distributed species, M. linariifolia Sm., produce a similar leaf oil and may provide opportunities to expand the genetic base of plantations. Growth and oil traits were assessed for 60 half-sib families, representing three chemical forms of Melaleuca alternifolia, and 10 half-sib families of the terpinen-4-ol rich chemical form of M. linariifolia, in a provenance/progeny trial in northern New South Wales, Australia. Differences in oil composition and coppicing between the terpinen-4-ol rich forms of the two species were significant (P 〈 0.05), while differences in growth traits and leaf oil yield were not significant. The difference in oil composition between northern and southern populations of M. linariifolia was as great as differences between the two species, suggesting the two regions should be considered distinct races for breeding purposes. Narrow-sense heritabilities in M. alternifolia of 0.67 for oil yield, 0.25 for plant dry weight, and 0.27 for coppice indicate substantial improvement would follow selection for single traits. However, negative genetic correlations between oil yield and plant dry weight indicate it is not possible to simultaneously achieve major gains in the two traits. Using combined index selection with a restriction on plant dry weight, expected gains of 17% in oil yield and 14% in coppicing are predicted from one generation of selection at an intensity of one tree in ten.
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