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Thomas M. Gradziel and Mary Ann Thorpe

Somatic mutations in shoot growing points, while considered relatively common in many horticultural clones, cannot be detected unless the mutation results in a distinguishable change and comes to occupy sufficient shoot area to be observable. Noninfectious bud-failure (BF) in almond, a genetic mutation which results in failure during early development of vegetative but not flower buds, behaves as a chimera in its incidence within an affected tree and in vegetative progeny from bud-failure prone clonal sources (i.e., vegetative lineage). Early stages of BF development are thought to occur as very limited and so undetected sectorial or mericlinal chimeras. Detection of BF during these early stages would be very valuable for the selection of low-BF source clones for nursery increase. Flower symmetry, as measured by differences in the size of each of the five petals of an almond flower, was evaluated as an indicator of the relative fitness of the individual cell lineages from which different petals were derived. Several hundred flowers from individual clonal sources of the almond variety `Nonpareil', known to produce either very low, medium, or very high levels of BF in their vegetative progeny, were tested over 3 separate years. Significant reductions in flower symmetry were consistently observed for medium BF potential clonal sources relative to either low- or high-BF sources despite the lack of any observable BF symptoms in the medium-BF trees tested. Associated with asymmetric-flower-prone sources was a greater number of an easily distinguishable distorted petal morphology. Medium BF-potential sources consistently produced 2- to 3-fold greater numbers of this petal morphology relative to low BF-sources, although the occurrence of distorted petals in both low and medium BF sources limits its use as an efficient field selection tool. Research findings, however, are allowing a more detailed understanding of the developmental ontogeny of “bud-sport” mutations and may have application in the analysis of otherwise hidden chimeras resulting from either somatic mutations or genetic transformation/regeneration schemes.

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Liuhui Yang, Jianjun Zhang, Jaime A. Teixeira da Silva and Xiaonan Yu

. (Beijing, China). Chromosome measurements were made using five well-spread metaphase plates per population. Karyotype analysis was performed using the criteria described by Chen et al. (2003) and Li and Zhang (1982) . Karyotype symmetry was classified

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Diana R. Cochran and Amy Fulcher

for total surface area of a cone, {(π × half-width 2 ) + [(π × half-width) × √(half-width 2 + height 2 )]}, to account for the overall shape of the flower. A visual quality rating assessed branch symmetry at the end of the experiments on a 1–7 scale

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Diana R. Cochran, Amy Fulcher and Guihong Bi

-width (half-width = 0.5 × flower width) to account for the overall shape of the flower (panicle). Additionally, branch symmetry, a measure of plant quality, was assessed by determining overall plant architecture (plant size, density, and branch symmetry) and

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S.H. Jalikop and Ravindra Kumar

were mature to record the following data: 1) date of harvest; 2) fruit weight in grams; 3) date of ripening, when the entire fruit was soft; 4) ripe fruit weight in grams; 5) fruit symmetry, visually graded as conical, oblate, oblique, and irregular; 6

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Christopher L. Rosier, John Frampton, Barry Goldfarb, Farrell C. Wise and Frank A. Blazich

Seven concentrations of indole-3-butyric acid (IBA), seven concentrations of 1-naphthaleneacetic acid (NAA), and a nonauxin control were tested over three growth stages to determine their ability to promote adventitious rooting of stem cuttings from 3- and 4-year-old stock plants of virginia pine (Pinus virginiana Mill.). Cuttings were harvested September 2000 (semi-hardwood), February 2001 (hardwood), June 2001 (softwood), and October 2001 (semi-hardwood), treated with auxin concentrations ranging from 0 to 64 mm and placed under intermittent mist in a greenhouse. Rooting percentage, percent mortality, number of primary roots, total root length, root symmetry, root angle, and root diameter were assessed following 16 weeks. Growth stage affected every rooting trait measured except root symmetry and diameter. Auxin type affected total root length and root diameter, while auxin concentration affected every rooting trait except root angle. The highest predicted rooting percentages (46%) occurred when semi-hardwood cuttings were collected in September 2000 and treated with 7 mm auxin. Cuttings collected within the same growing season (2001) exhibited the highest predicted rooting percentage (33%) when softwood cuttings were treated with 6 mm auxin. Semi-hardwood cuttings rooted in 2001 produced the greatest number of roots and root lengths. Root diameter was significantly greater when NAA rather than IBA was applied, especially at higher concentrations.

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Wol-Soo Kim* and Jung-An Jo

This study was carried out to observe the effects of the pruning strength and the growth regulator on shoot growth and fruit shape in Pyrus pyrifolia cv. Niitaka. GA paste (GA) was known as a promoter of malformed fruits, but Mepiquat as an inhibitor. Light pruning treatment, of which removed the half of lateral shoots, decreased leaf area, weight, thickness, and the length of shoots and internodes in comparison to severe pruning. The occurrence of calyx perpetual fruit (CPF) in fruitlet stage was higher about 45% in severe pruning than in light pruning. Light pruning decreased malformed fruit by 10% compared to severe pruning at harvest stage, but there was no difference in soluble solid content of fruits between two treatments. Also light pruning decreased fruit weight. GA paste treatment on 50 days after full bloom significantly increased fruit weight, but Mepiquat decreased. In treatment of Mepiquat and GA the occurrence of malformed fruit was 31.3% and 35%, respectively and the index of symmetry was higher than control. Therefore, these results suggested that the light pruning has a positive effect on the production of symmetry fruit.

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Christopher L. Rosier, John Frampton, Barry Goldfarb, Farrell C. Wise and Frank A. Blazich

Two experiments were conducted to develop a protocol for rooting stem cuttings from 3-, 5-, and 7-year-old fraser fir [Abies fraseri (Pursh) Poir.] Christmas trees. The first experiment tested the effect of stumping treatments and tree age on shoot production and subsequent adventitious rooting. One auxin concentration [4 mm indole-3-butyric acid (IBA)] and a nonauxin control were tested. Stock plants were stumped to the first whorl (trees in the field 3 and 5 years) or the first, third, and fifth whorls (trees in the field 7 years). Intact (nonstumped) controls were also included for each age. The second experiment was designed to create a quantitative description of the effects that crown (foliage and above ground branches of a tree) position have on the rooting of stem cuttings collected from stumped and nonstumped trees. The exact position was determined by measuring the distance from the stem, height from the ground, and the degrees from north. Crown positions were recorded as cuttings were collected and then cuttings were tested for rooting response. The rooting traits assessed in both experiments included rooting percentage, percent mortality, number of primary roots, total root length, root symmetry, and root angle. In the first experiment, rooting percentage, primary root production, and total root length increased as the age of the stock plant decreased and the severity of the stumping treatment increased. Auxin treatment significantly increased rooting percentage, root production, root lengths, and root symmetry while decreasing mortality. Overall, the highest rooting percentages (51%) and the greatest number of primary roots (8.1) occurred when 3-year-old stock plants were stumped to the first whorl and treated the cuttings with 4 mm IBA. The greatest total root lengths (335 mm) occurred in cuttings from the 3-year-old stock plants. In the second experiment, rooting percentage was significantly affected by the position from which the cuttings were collected. Cuttings collected lower in the crown and closer to the main stem rooted more frequently than cuttings collected from the outer and upper crown.

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Christopher L. Rosier, John Frampton, Barry Goldfarb, Frank A. Blazich and Farrell C. Wise

Seven concentrations of IBA and seven concentrations of NAA plus a nonauxin control were tested over three growth stages to determine their effectiveness in promoting adventitious root formation on stem cuttings taken from 3- and 4-year-old stock plants of Fraser fir [Abies fraseri (Pursh) Poir.]. Cuttings were prepared in March (hardwood), June (softwood), or November (semi-hardwood) 2001, treated with auxin concentrations ranging from 0 to 64 mm, and placed under mist. Rooting percentage, percent mortality, number of primary roots, total root length, root system symmetry, and root angle were recorded after 16 weeks. Growth stage and auxin concentration significantly affected every rooting trait except root angle. NAA significantly increased the number of primary roots and total root length. However, auxin type did not significantly affect rooting percentage or percent mortality. The highest rooting percentages (99%) occurred when softwood cuttings were treated with 5 mm auxin, however, semi-hardwood cuttings also rooted at high percentages (90%) and had no mortality when treated with 14 mm auxin. Regardless of auxin type, the number of primary roots and total root length varied in similar patterns across concentration, although, NAA tended to induce a greater response. To root Fraser fir stem cuttings collected from 3- and 4-year-old stock plants, it is recommended that a concentration of 5 mm NAA should be used on softwood cuttings and 14 mm IBA on semi-hardwood cuttings. Chemical names used: indole-3-butyric acid (IBA); 1-naphthaleneacetic acid (NAA).

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Wol-Soo Kim* and Xiu-Yu We

Consumers in the United States. and the European Union prefer to purchase medium-sized and symmetrical pears, while most Koreans prefer fruit that is as large as possible. This study was carried out to determine the effect of fruit loading, thinning time, and water management at full bloom stage on the number of seed and size and shape of fruit. As fruit loading increased and the time of fruit thinning was delayed, there was a decrease in fruit weight. The rate of fruit weight under 450 g was 41.7% in the treatment of 30% increase of fruit loading compared to control. There was an increasing tendency of symmetry fruits as the increase of fruit loading. By water stress treatment for 30 days after full bloom, a lot of medium sized fruit were harvested. The rate of symmetrical fruits was increased from the fruit, which held nine to ten seeds per fruit as well as uniformed seed development. Therefore, these results suggested that the number of seed s per fruit showed a close relationship to fruit shape, but water stress and fruit thinning time did not affect the fruit shape.