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Robert D. Belding, Sylvia M. Blankenship, Eric Young, and Ross B. Leidy

Variation in amount and composition of epicuticular wax among several apple (Malus ×domestica Borkh.) cultivars was characterized by gas chromatography, thin-layer chromatography, and gas chromatography-mass spectroscopy. Across cultivars, wax mass ranged from 366 to 1038 μg·cm-2. Wax mass decreased during the 30 days before harvest. Ursolic acid accounted for 32% to 70% of the hydrocarbons that make up the epicuticular wax. Alkanes, predominantly 29-carbon nonacosane, comprised 16.6% to 49%. Primary alcohols of the hydrocarbons ranged from 0% to 14.6% of the epicuticular wax. Secondary alcohols of the hydrocarbons were the most cultivar specific, making up 20.4% of the epicuticular wax in `Delicious' and only 1.9% `Golden Delicious' strains. Aldehydes and ketones of the hydrocarbons represented a small amount of total wax, ranging from 0% and 6.0%. Percentage of primary alcohol in the epicuticular wax increased as fruit developed. Other components showed no distinct trends with fruit development. Examination of the ultrastructure of cuticular wax using scanning electron microscopy revealed structural differences among cultivars.

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E.A. Guertal and C.B. Elkins

Photosynthetically active radiation (PAR) was measured at two times of day (8:00 am and noon Central Standard Time) in a 915 × 915-cm area of a 1006 × 915-cm gable roof greenhouse. PAR measurements were taken across a grid at 40-cm intervals, a total of 529 data points. Spatial variation of PAR in the greenhouse was evaluated through contour plots and the geostatistical technique of semivariogram construction. Semivariograms provide a visual guide to the degree of spatial correlation of a variable, allowing a quantification of the distance at which variables cease to be spatially correlated (the range) Measured PAR contained distinct zones of lowered values, a function of overhead greenhouse structures, wall-hung electrical boxes, and tall plants in adjacent greenhouses. Although the amount of PAR changed over time, zones of high and low PAR remained relatively constant, except at the sides of the greenhouse. Constructed semivariograms revealed that PAR contained strong spatial correlation (up to a 350-cm separation) as measured in the north-south direction, moving parallel to greenhouse bench placement. When PAR measurements perpendicular to benches (east-west) were used in directional semivariograms PAR was found to be completely random, plotting as a horizontal line called a nugget effect. Thus, plants placed perpendicular to the greenhouse benches (east-west) would not be affected by the spatial correlation of PAR.

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Wai-Foong Hong, Chang-Qing Bai, Michael Broe, Jinguo Hu, Charles Krause, David Tay*, and Guo-Liang Wang

Pelargonium is one of the important flower crops in USA. It is a priority genus for conservation at the USDA Ornamental Plant Germplasm Center (OPGC). It belongs to Geraniaceae family and comprises of about 280 species. To understand the genetic variation of the Pelargonium collection at OPGC, the PCR-based TRAP (target region amplified polymorphism) marker system which was newly developed in sunflower was used in this study. Twelve sets of primers were used to fingerprint 46 accessions representing 21 commercial P. hortorum, 17 scented geraniums and 8 other unidentified Pelargonium taxa. About 150 DNA bands could be detected in each primer and accession combination. Cluster analysis showed that molecular data was highly correlated with the phenotypes. Cultivars with similar morphological traits were clustered together. These results demonstrated that the TRAP system is a useful technique for the characterization and classification of Pelargonium collections.

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Vicky W. Lee, H.P. Vasantha Rupasinghe*, and Chung-Ja Jackson

Apples are excellent sources of dietary phenolics, in particular flavonoids and chlorogenic acid, which are potent antioxidants that may play important roles in the prevention of chronic diseases. This study investigated the major phenolics profiles of apple fruit in relation to (1) the distribution among 8 Ontario-grown cultivars, (2) the different fruit parts, and (3) the effect of processing of fresh-cuts. In addition, total antioxidant capacity (TAC) and total phenols content (TPC) were measured in apples by spectrophotometric assays. Flavonoids and chlorogenic acid were quantified using HPLC/PDA. Vitamin C was quantified using HPLC/Fluorescence. TAC, TPC and flavonoids levels were the highest in Honey Crisp and Delicious, moderate in Idared, Spartan, Granny Smith, and Cortland, and the lowest in Crispin and Empire. Apple peel contained 2 to 10-fold higher TAC, TPC and total of 10 major phenolics than that of core and flesh indicating peeling of apples during processing could reduced significantly the nutritional quality of fresh-cut apples. Dihydrochalcone (phloridzin) and chlorogenic acid levels were 2 to 21-fold higher in apple core than skin and flesh. TAC levels and vitamin C contents could be increased up to 3-fold and 14 to 20-fold, respectively by the post-cut dipping treatment with an ascorbic acid-based antioxidant formula. The phenolic profiles of sliced apples were stable up to 21 days at 4°C.

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Mwamburi Mcharo*, Don Labonte, Chris Clark, and Mary Hoy

Using two sweetpotato (Ipomoea batatas (L.) Lam) F1 populations from diverse environments we investigated the AFLP marker profiles of the genotypes for association studies between the molecular markers and southern root-knot nematode (Meloidogyne incognita) resistance expression. Population one consisted of 51 half-sib genotypes developed at the Louisiana State Univ. AgCenter. The second population consisted of 51 full-sibs developed by the East African and International Potato Center sweetpotato breeding programs. Results for nematode resistance expression indicate a binomial distribution among the genotypes. Using analysis of molecular variance, logistic regression and discriminant analysis, AFLP markers that are most influential with respect to the phenotypic trait expression were selected for both populations. A comparative analysis of the power of models from the two statistical models for southern root-knot nematode resistance class prediction was also done. The diversity and possible universal similarity of influential markers between the two populations and the expected impact in sweetpotato breeding programs will be discussed.

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Charles R. Clement and Richard M. Manshardt

The pejibaye (Bactris gasipaes, Palmae) is being evaluated in Hawaii as a source of fresh hearts of palm. Nine open-pollinated progenies from the Benjamin Constant population of the Putumayo landrace are planted at three sites in a RCB. The best site started yielding at 15 months after planting, the intermediate at 16 months, the poorest at 18 months. During the first four months of harvest at the best site, 25% of the plants were cut; during three months at the intermediate site, 15% were cut; during the first cut at the poor site, 1% were cut. Progeny harvest percentages ranged from 7 to 53% at the best site, with only three progenies above average (33, 47, 53%). These are considered to be precocious. These three progenies produced average size hearts (172±36, 204±57, 203±44 g/plant, respectively; experimental mean±SD = 205±53 g), but yielded above average at 5000 plants/ha (275, 480, 524 kg/ha, respectively; exp. mean = 272 kg; corrected for % cut). Potential yields of these progenies were near the mean (871±198, 1018±280, 983±197 kg/ha, respectively; exp. mean = 986±381 kg/ha), but their precocity provides early returns to the farmer.

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Zhigiang Zhu and Paul G. Thompson

The polymorphisms of phosphoglucose isomerase (PGI) in sweetpotato and I. trifida were examined. Horizontal starch gel electrophoresis was used to analyze leaf and pollen tissue of parents and progenies of 10 crosses. Analyses revealed that PGI was a dimeric enzyme system controlled by 5 loci. The segregation ratios did not suggest that PGI was a duplicate system and therefore did not indicate hexaploidy. Only 2 loci appeared to be present in I. trifida. No observed band was related to different ploidy levels in I. batatas and I. trifida. No linkage was identified among the loci.

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Chuhe Chen, J. Scott Cameron, and Stephen F. Klauer

Accumulated attendance and fourth-derivative spectra were measured using intact leaf samples at mom temperature for 80 genotypes of four Fragaria species. Attendance peak wavelength and amplitude data of all samples was pooled and yielded 25 common bands for Fragaria. Of these, 14 chlorophyll bands and two phototransformed bands were consistent with French's (1972) model.

Peak wavelengths and amplitudes which represent major bands in F. chiloensis and F. × ananassa spectra were also determined separately. While peak wavelengths of the two species were identical, variation was noted in peak amplitude. The signals of the bands at Cb640, Cb649, Ca670, Ca673, Ca675-676, Ca684 and Ca693 in F. chiloensis were significantly stronger than those in F. × ananassa. Ca677 and Ca695 were stronger in F. × ananassa.

The greatest difference among Fragaria species was found in the amplitude of Ca693. The amplitude of this peak was greatest in F. chi/oensis (0.0025) and smallest in F. virginiana (-0.0005), The cultivated hybrid of these two species, F. × ananassa, was intermediate (0.0008), Preliminary evidence suggests that certain genotype-specific spectral characteristics may relate directly to observed differences in photosynthetic biology among these species.

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Michael J. Havey

Restriction fragment length polymorphisms (RFLPs) in the chloroplast and nuclear genome are useful for estimation of phylogenetic relationships. Fifteen mutations at restriction enzyme sites in the chloroplast DNA were discovered. The wild species A. oschaninii and A. vavilovii were identical to A. cepa for all mutations. These species represent sources of wild germplasm closely related to the bulb onion. Nuclear RFLPs are now being used to estimate the genetic distances between accessions of A. oschaninii A. vavilovii, and open-pollinated populations of the cultivated bulb onion.

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Richard W. Hartmann

F3 seeds from a cross of P. erosus (indeterminate, daylength sensitive) X P. ahipa (determinate, daylength insensitive) were received from M. Sorensen of the Royal Veterinary and Agricultural University in Copenhagen, Denmark and sown in Hawaii in April, 1989 to increase the seed. The F4 seed were planted in March, 1990 and in October, 1990 (the normal time). All F4 progeny included both bush and vine plants in the summer planting, with more bush plants in the progeny of F3 bushes than vines. Likewise, the progeny of earlier-flowering F3 plants had a higher percentage of plants in flower in June than progeny of later-flowering ones. Root sizes and shapes were variable. The F4 progenies of the lines with the highest percentage of bushes and early-flowering plants were regrown in the summer of 1991 and selected for summer-flowering bush plants with acceptable root size. The selections were then grown in the winter of 1991 to test for performance during the normal growing season.