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Desmond R. Layne, Zhengwang Jiang, and James W. Rushing

Replicated trials were conducted in summers of 1998 and 1999 at two commercial orchards (A and B) to determine the influence of a metalized, high-density polyethylene reflective film (SonocoRF, Sonoco Products Co., Hartsville, S.C.) and ReTain (Abbott Laboratories, Inc., N. Chicago, Ill.), on fruit red skin color and maturity of `Gala' apples. There were four experimental treatments: i) Control; ii) Reflective Film (RF); iii) ReTain; and iv) RF + ReTain. RF was laid 4 weeks before anticipated first pick date by laying a 5-ft-wide strip of plastic on either side of the tree row in the middle. ReTain was applied 4 weeks before harvest at the commercial rate in one orchard (A) and at 60% the commercial rate in the other orchard (B). At harvest, two 50-fruit samples were picked from each of four replicate blocks per treatment. All fruit were sized and visually sorted for color (1 = 0% to 25%, 2 = 26% to 50%, 3 = 51% to 75%, and 4 = 76% to 100% red surface, respectively). A 10-fruit subsample was selected following color sorting and evaluated for puncture pressure, soluble solids concentration (SSC) and starch hydrolysis. ReTain delayed maturity and reduced preharvest drop of `Gala'. Fruit from RF trees had a significantly greater percent red surface than fruit from trees not treated with RF. Fruit from RF + ReTain were significantly redder and had higher SSC than fruits from trees treated with ReTain alone. There were no differences in size, puncture pressure or starch hydrolysis between RF and RF + ReTain. RF appears to be a means to ensure greater redness in `Gala' treated with ReTain in South Carolina.

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Desmond R. Layne, Zhengwang Jiang, and James W. Rushing

Replicated trials were conducted in summers of 1998 and 1999 at several commercial orchards to determine the influence of a metalized, high-density polyethylene reflective film (SonocoRF, Sonoco Products Co., Hartsville, S.C.) on fruit red skin color and maturity of peach cultivars that historically have poor red coloration in South Carolina. At each site there were two experimental treatments: i) Control; and ii) Reflective Film (RF). RF was laid 2 to 4 weeks before anticipated first pick date by laying a 5-ft-wide strip of plastic on either side of the tree row in the middles. Treatment blocks at a given farm ranged from 0.5 to 1 acre in size and each treatment was replicated four times at each site. At harvest, two 50-fruit samples were picked from each block per treatment. All fruit were sized and visually sorted for color (1 = 0% to 25%, 2 = 26% to 50%, 3 = 51% to 75%, and 4 = 76% to 100% red surface, respectively). A 10-fruit subsample was selected following color sorting and evaluated for puncture pressure and soluble solids concentration (SSC). All cultivars tested (CVN1, Loring, Bounty, Summer Gold, Sun Prince, Cresthaven, and Encore) experienced significant increases in percent red surface when RF was used in 1998 and 1999. This color improvement ranged from 16 to 44% (mean = 28%). On average, fruits from RF were 0.8 lb softer and had 0.3% higher SSC than control fruits. Growers harvested more fruit earlier and in fewer picks for RF. Fruit size was not affected by RF. The influence of RF on orchard microclimate and quality and quantity of reflected light will be discussed.

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Zhengwang Jiang, Shengmei Wang, Renhuang Huang, Zhonghui Zhang, and Hongwen Huang

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Zhengwang Jiang, Feiyan Tang, Hongwen Huang, Hongju Hu, and Qiliang Chen

The sand pear (Pyrus pyrifolia Nakai) is an important fruit crop in China. In this study, simple sequence repeats (SSRs) were used to estimate the level and pattern of genetic diversity among 233 sand pear landraces collected from 10 different geographic regions in China. The results demonstrated that the SSR technique is an effective tool for assessing genetic diversity and the geographic pattern of genetic variation among sand pear landraces of different origins. A total of 184 putative alleles was detected using 14 primer pairs with an average of 13.1 alleles per locus. The mean expected heterozygosity and observed heterozygosity across all loci were 0.705 and 0.671, respectively. High genetic diversity was found in all populations except for that originated from Jiangxi (A e = 3.149; H e = 0.655), whereas at the regional level, those from central China were less diverse than those from other regions. Analysis of molecular variance showed that most genetic differences resided among landraces within populations. Additionally, unweighted pair group with arithmetic average clustering and principal component analysis plotting based on Nei's genetic distance revealed distinct gene pools in agreement with geographic distribution.

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Caihong Zhong, Shengmei Wang, Zhengwang Jiang, and Hongwen Huang

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Hongwen Huang, Ying Wang, Zhonghui Zhang, Zhengwang Jiang, and Shengmei Wang

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Hongwen Huang, Shengmei Wang, Renhuang Huang, Zhengwang Jiang, and Zhonghui Zhang

'Jintao' is a new yellow-fleshed kiwifruit (Actinidia chinensis Planch) developed from the breeding program at the Wuhan Institute of Botany (WIB), in Wuhan, Hubei, People's Republic of China. 'Jintao' is a midseason cultivar that ripens three to four weeks before the standard commercial cultivar [A. deliciosa (A. Chev.) C.F. Liang et A.R. Ferguson] 'Hayward'. It is sweeter than 'Hayward' and has a smooth skin. 'Jintao' was selected from A. chinensis and offers growers in warmer climates an alternative to 'Hayward', because of its higher productivity, better fruit quality, and improved heat tolerance. 'Jintao', which means golden peach in Chinese, is named in recognition of its yellow flesh and the common Chinese name, Mihou-tao, or monkey peach.

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Desmond R. Layne, Zhengwang Jiang, and James W. Rushing

Replicated trials were conducted during the summers of 1998 and 1999 at commercial orchards in South Carolina to determine the influence of ground application of a metalized, high density polyethylene reflective film on fruit red skin color and maturity of peach (Prunus persica) cultivars that historically have poor red coloration. At each site there were two experimental treatments: 1) control and 2) reflective film (film). Film was applied 2 to 4 weeks before anticipated first harvest date by laying a 150-cm (5-ft) wide strip of plastic on either side of the tree row in the middles. Treatment areas at a given farm ranged from 0.25 to 0.5 ha (0.5 to 1.0 acre) in size and each treatment was replicated four times at each site. At harvest, two 50-fruit samples were picked from each plot per treatment. All fruit were sized and visually sorted for color (1 = 0% to 25%, 2 = 26% to 50%, 3 = 51% to 75%, and 4 = 76% to 100% red surface, respectively). A 10-fruit subsample was selected following color sorting and evaluated for firmness and soluble solids concentration (SSC). All cultivars tested (`CVN1', `Loring', `Bounty', `Summer Gold', `Sunprince', `Cresthaven' and `Encore') experienced significant increases in percent red surface when film was used in 1998 and 1999. This color improvement ranged from 16% to 44% (mean = 28%). On average, fruit from film were 4.2 N (0.9 lb force) softer and had 0.3% higher SSC than control fruit. Growers harvested more fruit earlier and in fewer harvests for film. Fruit size was not affected by film. Reflected solar radiation from film was not different in quality than incident sunlight. Film resulted in an increase in canopy air temperature and a reduction in canopy relative humidity during daylight hours.

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Desmond R. Layne, Zhengwang Jiang, and James W. Rushing

Replicated trials were conducted in Summers 1998 and 1999 at two commercial orchards (A and B) to determine the influence of a metalized, high density polyethylene reflective film (SonocoRF) and aminoethoxyvinylglycine (ReTain), on fruit red skin coloration and maturity of `Gala' apples (Malus sylvestris var. domestica). There were four experimental treatments: 1) nontreated control; 2) reflective film (RF); 3) ReTain; and 4) RF + ReTain. RF was applied 4 weeks before anticipated start of harvest by laying a 5-ft-wide (150-cm) strip on each side of the tree row in the row middle. ReTain was applied 4 weeks before harvest at the commercial rate in one orchard and at 60% of the commercial rate in a second test. ReTain delayed fruit maturity. Fruit from RF trees had a significantly greater percent surface red color than fruit from trees not treated with RF. Fruit from RF + ReTain were significantly redder and had higher soluble solids concentration (SSC) than fruit from trees treated with ReTain alone. There were no differences in size, fruit firmness or starch content between fruit from RF and RF + Retain. RF appears to be a method to increase red skin coloration in `Gala' apples treated with ReTain without adversely impacting maturity.