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K.H.S. Peiris, G.G. Dull, R.G. Leffler, and S.J. Kays

Spatial variation in soluble solids content (SSC) of fruits of apple (Malus ×domestica Borkh. cv. Red Delicious), cantaloupe (Cucumis melo L. Cantaloupensis group), grapefruit (Citrus paradisi Macf. cv. Indian River Ruby Red), honeydew melon (Cucumis melo L. Inodorus group), mango (Mangifera indica L. cv. Hayden), orange (Citrus sinensis L. Osbeck. cv. Valencia), peach (Prunus persica L. Batsch. cv. Windblow), pineapple (Ananas comosus L. Merr. cv. Kew) and tomato (Lycopersicon esculentum Mill.), and of bulbs of onion (Allium cepa L. Cepa group) and in dry-matter content (DMC) of potato (Solanum tuberosum L. cv. Russet Burbank) tubers was measured along three directional orientations (i.e., proximal to distal, circumferentially midway along the proximal to distal axis, and radially from the center of the interior to the outer surface). The pattern and magnitude of constituent variation depended on the type of product and the direction of measurement. Radial and proximal to distal variation was greater than circumferential variation in all the products tested. Honeydew had the highest radial variation with a SSC difference of 6.0 % and a cv of 22.8%, while tomato displayed lower radial variation with a cv of 1.0%. Pineapple had a proximal to distal SSC difference of 4.6% with a cv of 13.8%, while the difference in tomato was 0.6% with a cv of 5.1%. Circumferential variation of SSC in all products tested was <2% with cv ranging from 1.1% to 3.8%. The results confirm that considerable constituent variability exists within individual fruit and vegetable organs. This variability may affect the accuracy of calibration equations and their prediction capability. Therefore, within-unit constituent variability should be meticulously assessed when an NIR spectrometric method is being developed for the nondestructive quality evaluation and sorting of a product.

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Abigail J. Walter, YongPing Duan, and David G. Hall

has been regulated since 2008 as a result of concerns of M. paniculata being a reservoir of C Las for commercial citrus ( Clark, 2007 ). C Las transmission between Citrus sinensis (L.) Osbeck var. ‘Madam Vinous’ and M. paniculata by ACP has

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Graham H. Barry, William S. Castle, and Frederick S. Davies

The objectives of this study were to determine whether juice quality of `Valencia' sweet orange [C. sinensis (L.) Osb.] is affected by the type of inflorescence on which fruit are borne, and to determine the contribution of inflorescence type to within-tree variation in juice quality. During the 1998-99 and 1999-2000 seasons, fruit size and juice quality [soluble solids concentration (SSC) and titratable acidity (TA)] of fruit from `Valencia' sweet orange trees on Carrizo citrange rootstock [Poncirus trifoliata (L.) Raf. × C. sinensis (L.) Osb.] planted in 1987 at Howey-in-the-Hills, Fla., were measured. A 2×2 factorial design (inflorescence type × canopy position) with leafy and leafless inflorescence types, and southwest top and northeast bottom canopy positions was used. The type of inflorescence on which fruit were borne had a minor effect on juice quality, and inflorescence type and juice quality were not directly associated. Rather, juice SSC was associated with the effect of inflorescence type on fruit size, as small fruit tended to have higher SSC than large fruit, regardless of the type of inflorescence on which fruit were borne. The relatively small difference in SSC between fruit borne on leafy and leafless inflorescences (≈3% of mean SSC) was an indirect result of fruit size. Therefore, fruit borne on leafy inflorescences, which tend to be of larger size compared with fruit borne on leafless inflorescences, tended to have marginally lower SSC. Acid content and ratio of SSC: TA were not related to inflorescence type. In addition, the type of inflorescence on which fruit were borne made only a nominal contribution to variability in juice SSC, in contrast to the major contribution of canopy position to within-tree variation in juice SSC. Factors other than inflorescence type are important components of within-tree variation in juice SSC.

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Lawrence R. Parsons, T. Adair Wheaton, and George Yelenosky

Handwarmers placed inside conventional insulating tree wraps increased trunk temperatures and improved tree survival under freeze conditions. Handwarmers generate heat by oxidation of Fe powder. In freeze-chamber tests with air temperature as low as –7.1C for 4 hours, wraps plus handwarmers kept trunk temperatures above freezing. Handwarmers increased minimum temperatures by 7C during a one-night freeze. Benefit of the handwarmer decreased the second night of a simulated two-night freeze but still increased minimum temperature by 1.3C. Tree survival was significantly improved by handwarmers in the freeze-chamber tests. In a field test during a mild freeze, handwarmers increased the minimum temperature by 3.5C the first night but provided no benefit the second night.

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Kim D. Bowman

Secure identification of individual plants by some kind of labels in the field is an important part of many types of horticultural, plant science, and ecological research. This report describes implanted microchips as one method of plant tagging that is reliable, durable, and secure. This technology may be especially useful in long-term experiments involving perennial woody plants. Two methods are described for implanting microchips in citrus trees that would also be applicable to other woody plant species. One method of implanting microchips is demonstrated to have no deleterious effect on citrus tree growth through the first 18 months after implantation into the tree. Since microchips implanted beneath the bark will become more deeply embedded in wood as the plants grow, signal penetration through wood was evaluated and determined to be sufficient for long-term field utility. Implanted microchips are potentially useful for secure tagging of valuable or endangered plant species to deter theft by providing secure and conclusive identification.

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Zhiyong Hu, Qing Liu, Meilian Tan, Hualin Yi, and Xiuxin Deng

from the cross between the diploid polyembryonic tangerine BDZ ( Citrus reticulata cv. Huanongbendizao) and the allotetraploid somatic hybrid HR [Hamlin sweet orange ( Citrus sinensis ) + rough lemon ( Citrus jambhiri )] ( Deng et al., 1996 ). Recently

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Eduardo J. Chica and L. Gene Albrigo

.J. 1985 Shoot development in Citrus sinensis L. (Washington Navel orange). I. Floral and inflorescence ontogeny Bot. Gaz. 146 320 326 Mandel, M.A. Yanofsky, M. 1995 A gene triggering flower formation in Arabidopsis Nature 377 522 524 Mathieu, J

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Rongcai Yuan, Ulrich Hartmond, and Walter J. Kender

Endogenous concentrations of IAA and ABA in the peel, pulp, seed, and abscission zone of mature `Valencia' oranges [Citrus sinesis (L.) Osbeck] were determined by high-performance liquid chromatography and enzyme-linked immunosorbent assay from early November 1998 to mid-June 1999. Ethylene production of mature `Valencia' oranges during the same period was determined by gas chromatography. IAA concentrations in the pulp and seed were three to five times lower than those in the peel over the 7-month observation period. IAA concentration in the abscission zone and peel was high from late April to mid-May, the period of less responsiveness to abscission chemicals. ABA concentration in the pulp was low over the entire observation period. ABA concentration in the abscission zone and peel was low during the less responsive period. Ethylene production was always low except for a slight increase during late December and early February. The IAA to ABA ratio was high in the fruit abscission zone during the less responsive period. Fruit detachment force of CMN-pyrazole-treated fruit was positively correlated with the ratio of endogenous IAA to ABA or endogenous IAA, but negatively to endogenous ABA in the fruit abscission zone. These data suggest the balance between IAA and ABA in the fruit abscission zone may be an important factor in determining sensitivity and thereby the response of mature `Valencia' orange fruit to abscission chemicals. Chemical names used: abscisic acid (ABA); indole-3-acetic acid (IAA); 5-chloro-3-methyl-4-nitro-1H-pyrazole (CMN-pyrazole).

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Thomas H. Spreen and Marisa L. Zansler

. The rate of decline in grapefruit production exceeds the decline in orange production on a percentage basis. There has also been a steep decline in other fresh-market citrus types such as ‘Washington’ navel orange ( Citrus sinensis ) and both early