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  • Author or Editor: L.M. Martín x
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Fatty acid composition has been studied in seedlings from a diallel cross (nine families) among `Arbequina', `Frantoio', and `Picual' olive (Olea europaea L.). Variance among samples within genotype, genetic and environmental (yearly) variances, and year-to-year consistency of data were estimated. A correlation analysis of the standardized data for fatty acid composition between first and second year data was also carried out to select the most interesting genotypes as early as possible. The results showed that fatty acid composition exhibit significant differences between genotypes and years. The variance component attributable to differences between genotypes represented >60% of total variance for all the fatty acids evaluated. High correlation coefficients between the first and second year data were found for oleic and linoleic acid percentage; these correlations were slightly poorer for the other fatty acids analyzed. These results may be useful for improving the efficiency of olive breeding programs in first-stage selection on whole progeny populations.

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Spondias mombim L. fruit, commonly known in the Brazilian Northeast as “caj,” has increased its acceptance locally and abroad in recent years due to its exotic and delicious pulp. Spondias mombim fruit can be eaten raw or as juice, jellies, and sweet. Trade in S. mombim, however, has been limited by the highly perishable nature of the fruit. Comprehensive studies on proper postharvest technologies for its storage and enhanced shelflife are required to improve its commercial performance. The determination of proper storage temperature allows reducing the rate of metabolism without causing chilling injury. In addition, modified atmosphere packaging, by using low-density polyethylene (LDPE), may delay fruit ripening. Combination of proper temperature and film O2 and CO2 permeabilities, therefore, may enhance the postharvest shelflife of S. mombim fruits. Ripened fruits were stored with and without film, at temperatures varying from 16 °C to 5 °C, at 0.5 °C steps, in order to set proper storage temperature and shelflife. Changes in fruit weight loss, firmness, soluble solids, pH, titratable acidity, sugars, CO2 production, ascorbic acid, and carotenoids contents were measured during storage. Storage of S. mombim, wrapped with LDPE, at 8 °C allowed quality maintenance and increased the fruit postharvest shelflife by 12 days, without causing chilling injury.

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Six African bermudagrass (Cynodon transvaalensis Burtt-Davy) genotypes, one common bermudagrass [C. dactylon (L.) Pers. var. dactylon] genotype, and ‘Tifway’ (C. dactylon × transvaalensis) hybrid bermudagrass were evaluated for shoot type, leaf angle, and shoot angle. Evaluations were conducted to determine if these measurements could be used to differentiate among upright, intermediate, and prostrate growth habits. Significant differences were found for all three techniques, but attempts to group plants together as having prostrate, intermediate, or upright growth habits was not possible. ‘Tifway’ was intermediate between the African bermudagrass genotypes and the common genotype for shoot type observations, but was more similar to upright-growing African bermudagrass for leaf angle and the more prostrate-growing common bermudagrass for shoot angle. Quantification of shoot type and leaf angle did not appear as useful as shoot angle measurements for screening germplasm to identify upright or prostrate growth habits in bermudagrass.

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Phytophthora cinnamomi Rands, the causal pathogen of phytophthora root rot (PRR) of chestnut, is one of the main obstacles to growth of american chestnut [Castanea dentata (Marsh.) Bork.] in the southern part of its distribution. To facilitate introgression of PRR resistance of chinese chestnut (C. mollissima Blume) into a C. dentata genetic background, we assessed the disease resistance of 10 interspecific hybrid families derived from potentially resistant C. mollissima cultivars. Hybrid progeny were inoculated with P. cinnamomi in the nursery and assessed for root lesion severity after 1 year of growth. Asymptomatic plants were transplanted to a P. cinnamomi-positive orchard and evaluated for survival midway through the following growing season. During the nursery experiment, 8 of 10 hybrid families were not significantly different from susceptible C. dentata controls for average disease resistance scores. However, multiple asymptomatic individuals were identified in each of the eight families. Two of the 10 hybrid families were not significantly different from the resistant C. mollissima and C. henryi controls. In the P. cinnamomi-positive orchard, the prescreened hybrid families displayed a greater proportion of survivors than backcross families that had not been prescreened for P. cinnamomi resistance. Hybrid plants that have survived 2 years of growth in P. cinnamomi-infested potting media and soils represent an important step toward the production of genetically diverse chestnut populations in the southeastern United States that combine the PRR resistance of C. mollissima with the morphology and local adaptation of C. dentata.

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Three onion (Allium cepa L.) cultivars were grown to maturity at five S fertility levels and analyzed for S-alk(en)yl-L-cysteine sulfoxide (ACSO) flavor precursors, γ-glutamyl peptide (γ-GP) intermediates, bulb S, pyruvic acid, and soluble solids content. ACSO concentration and composition changed with S fertility, and the response was cultivar dependent. At S treatments that induced S deficiency symptoms during active bulbing, (+)S-methyl-L-cysteine sulfoxide was the dominant flavor precursor, and the flavor pathway was a strong sink for available S. As S fertility increased to luxuriant levels, trans(+)-S-(1-propenyl)-L-cysteine sulfoxide (PRENCSO) became the dominant ACSO. (+)S-propyl-L-cysteine sulfoxide was found in low concentration relative to total ACSO at all S fertility treatments. With low S fertility, S rapidly was metabolized and low γ-GP concentrations were detected. As S fertility increased, γ-GP increased, especially γ-L-glutamyl-S-(1-propenyl)-L-cysteine sulfoxide, the penultimate compound leading to ACSO synthesis. Nearly 95% of the total bulb S could be accounted for in the measured S compounds at low S fertility. However, at the highest S treatment, only 40 % of the total bulb S could be attributed to the ACSO and γ-GP, indicating that other S compounds were significant S reservoirs in onions. Concentrations of enzymatically produced pyruvic acid (EPY) were most closely related to PRENCSO concentrations. Understanding the dynamics of flavor accumulation in onion and other vegetable Alliums will become increasing important as the food and phytomedicinal industries move toward greater product standardization and characterization.

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Paclobutrazol at 0 and 750 μl·liter–1 was sprayed on shoots of Feijoa sellowiana O. Berg. and Ligustrum japonicum Thunb. grown under similar production regimes in central Arizona (subtropical desert) and southern Georgia (humid temperate). Five months after application, Feijoa and Ligustrum leaves were generally smaller and thicker in Arizona than in Georgia. Arizona leaves were thicker than those in Georgia because of more layers of palisade and spongy mesophyll cells. Compared with leaves from control plants, paclobutrazol 1) increased Feijoa leaf area in Georgia, 2) decreased Ligustrum leaf area at both locations by ≈50%, and 3) decreased leaf thickness of both species in Arizona. Arizona Feijoa leaves had trichomes on adaxial and abaxial surfaces, whereas Georgia Feijoa leaves had trichomes on abaxial surfaces only. Paclobutrazol increased trichome frequency on adaxial surfaces of Arizona Feijoa leaves. Stomatal frequency of Georgia Feijoa leaves was about doubled by paclobutrazol. Reflectance of near-infrared radiation by paclobutrazol-treated Feijoa leaves was 1.4 times higher than that of nontreated leaves in Georgia and 1.9 times in Arizona. Near-infrared reflectance by Georgia Ligustrum leaves was 1.3 times higher than by Arizona Ligustrum leaves and was not affected by paclobutrazol. Leaf reflectance of photosynthetically active radiation (PAR) by Arizona Feijoa was higher than by Georgia Feijoa. Paclobutrazol increased PAR reflectance by Arizona Feijoa leaves. In contrast, Georgia Feijoa PAR reflectance was decreased by paclobutrazol. Paclobutrazol or location did not affect Ligustrum PAR reflectance. Chemical name used: (2RS,3RS)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl)pentan-3-ol (paclobutrazol).

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Same-source rooted cuttings of Feijoa Sellowiana Hort. and Ligustrum japonicum L. were grown under identical production systems in Tempe, AZ, USA or Tifton, GA, USA during the Spring and Summer 1992. Leaf area was largest and specific leaf weight was lowest for all Georgia-grown plants. Scanning electron microscopy revealed that Arizona Feijoa leaves had trichomes on both the abaxial and adaxial leaf surfaces, whereas, leaves of Georgia Feijoa had trichomes on the abaxial surface only. Arizona Feijoa leaves also had increased abaxial surface pubescence compared to leaves of Georgia Feijoa. Both Feijoa and Ligustrum grown in Arizona had a higher density of palisade and spongy mesophyll cell layers compared to their Georgia counterparts. When placed under the same irradiance source, adaxial leaf surface temperatures of Georgia-grown Ligustrum and Feijoa were approximately 4.2 and 0.2C, respectively, higher than for those grown in Arizona. Higher leaf temperatures of Georgia-grown plants were correlated with darker leaf color compared to the Arizona-grown plants.

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Intensive selection to improve vase life was performed on a sample population of Gerber ×hybrida Hort. from a broad source of germplasm. Progeny of a 5 × 5 diallel cross yielded estimates of narrow sense heritability (h2 = 0.28) and broad sense heritability (H2 = 0.28) for vase life based on a mean of 1.96 measurements per plant. Additive gene action is postulated to control this character since the difference between total genotypic variance and additive genetic variance components was small. Repeatability (r = 0.57) based on a single measurement per plant was moderately high. Heritability estimates were also determined based on 1, 2, 3, 5, and ∞ measurements per plant. Heritability ranged from 22% to 39%.

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