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Teryl R. Roper and Marianna Hagidimitriou

Carbohydrate concentration may be important for flower initiation and fruit set in cranberry (Vaccinium macrocarpon Ait.). Fruit set has been shown to be a major limiting factor in yield component analysis. The objective of this research was to identify carbohydrate concentrations in cranberry tissues at various stages of development under field conditions. Samples of two cranberry cultivars, `Stevens' and `Searles' were collected during the 1989 season using a 13 cm diameter probe. Samples were divided into fruit, uprights, woody stems and roots. Carbohydrates were quantified by HPLC. Nonstructural carbohydrates were primarily sucrose, glucose, fructose and starch. Soluble carbohydrate concentration was stable throughout the season in tissues analyzed, while starch content was high early in the season then decreased during blossom and fruit set. This work shows that starch reserves in leaves and stems apparently are remobilized to support fruit set in cranberry.

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Jorge H. Siller-Cepeda, Leslie Fuchigami, and Tony H. H. Chen

Many seeds of woody plants require low temperature or other treatments to overcome dormancy. Changes in catalase activity and glutathione has been proposed to be associated with the breaking of dormancy. We examined the level of glutathione and catalase activity of cherry seeds (Prunus mahaleb cv. Lambert) exposed to several dormancy breaking agents. Seeds imbibed in water for 24 hrs. were either stratified at 4°C or at 25°C for up to 12 weeks, or exposed to other dormancy breaking agents. Germination test, glutathione and catalase activity were determined weekly and/or after treatment. Analysis of levels and state of glutathione were performed by high pressure liquid chromatography (HPLC), and catalase activity was assayed spectrophotometrically. Total glutathione in dry and imbibed seeds were similar, but, ratio between the reduced and oxidized form were different. Low temperature stratification for 12 weeks increased the reduced form of glutathione six-fold, while percent germination increased up to 94%.

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Jorge H. Siller-Cepeda, Leslie Fuchigami, and Tony H. H. Chen

Many seeds of woody plants require low temperature or other treatments to overcome dormancy. Changes in catalase activity and glutathione has been proposed to be associated with the breaking of dormancy. We examined the level of glutathione and catalase activity of cherry seeds (Prunus mahaleb cv. Lambert) exposed to several dormancy breaking agents. Seeds imbibed in water for 24 hrs. were either stratified at 4°C or at 25°C for up to 12 weeks, or exposed to other dormancy breaking agents. Germination test, glutathione and catalase activity were determined weekly and/or after treatment. Analysis of levels and state of glutathione were performed by high pressure liquid chromatography (HPLC), and catalase activity was assayed spectrophotometrically. Total glutathione in dry and imbibed seeds were similar, but, ratio between the reduced and oxidized form were different. Low temperature stratification for 12 weeks increased the reduced form of glutathione six-fold, while percent germination increased up to 94%.

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John R. Stommel

Sugar accumulation throughout fruit development in the cultivated tomato (Lycopersicon esculentum) and a wild green-fruited species (L. peruvianum) are being examined. Results obtained using HPLC demonstrate that the fruit of L. peruvianum accessions accumulate the disaccharide, sucrose, in addition to the monosaccharides, glucose and fructose, common to L. esculentum. When detectable, sucrose in the L. esculentum cultivar FM6203 was present at very low levels throughout development. Analysis of mature fruit of L. esculentum var. cerasiforme, L. pimpinellifolium, and L. cheesmanii accessions indicate glucose and fructose as the primary storage sugars. Similar to L. peruvianum, mature fruit of the green-fruited species, L. hirsutum f. typicum and L. hirsutum f. glabratum, accumulate sucrose in addition to glucose and fructose.

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E.A. Baldwin, J.W. Scott, T.M. Malundo, and R.L. Shewfelt

Sugars, acids, and flavor volatiles are components of flavor that have been measured instrumentally, revealing differences among tomato cultigens. For objective measurements to be useful, however, they need to relate to sensory data. In this study, objective and sensory analyses of tomato flavor were compared. Seven tomato cultigens were ranked for sweetness, sourness, and flavor and rated for overall acceptability by a panel of 32 experienced judges. Sucrose equivalents (SE), measured by HPLC, but not soluble solids correlated with sweetness at P = 0.10. In addition, SE highly correlated with flavor (P = 0.03), while titratable acidity (TA) negatively correlated with overall acceptability (P = 0.03). Regression analysis indicated that 2+3-methylbutanol, cis-3-hexenal, and 6-methyl-5-hepten-2-one significantly contributed to flavor at a 5% level of significance. It is apparent from this study that sucrose equivalents are more meaningful than soluble solids for measurement of sweetness, and that certain flavor volatiles play a role in tomato flavor.

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Jeanne A. Briggs, Mellissa B. Riley, and Ted Whitwell

The pesticides isoxaben, trifluralin, chlorpyrifos, and thiophanatemethyl were applied at recommended rates to a 4-ha growing bed at an operating container nursery. Runoff samples produced by overhead irrigation were collected from three waterways, 300 feet long × 6 feet wide. The waterways were a sodded hybrid bermudagrass, a plantation of common cattails (Typha latifolia), and a gravel–clay waterway used as a reference. A 2-ha area drained into the sodded waterway, which flowed into the cattails, and a 2-ha bed flowed into the reference waterway. Samples were collected throughout the duration of runoff on day of treatment and at 1, 2, 8, 15, and 22 days after treatment. Runoff volumes were recorded over time as measured at weirs. Analysis was by HPLC following solid-phase extraction. Only isoxaben was detected at 2 days after treatment. Initial concentrations of all pesticides were lower in the vegetated waterways than in the reference.

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Shahid N. Chohan and Terence A. Brown

HPLC was used to measure nucleotide pools in tomato seeds during the 3 h following imbibition in water. In dry seeds, nucleotides were predominantly in the form of monophosphates. During the first 2 h post-imbibition, the monophosphate levels declined and there were sharp increases in the amounts of diphosphates, followed by triphosphates. Between the 2nd and 3rd h, the di- and triphosphate levels continued to increase and the monophosphate levels began to recover, especially in the case of UMP—presumably the result of degradation of unwanted mRNAs left over from the maturation phase of seed development. The adenylate energy charge increased during imbibition and, within 3 h, reached a value close to that of normal active tissue.

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Naoki Yamauchi, Xiao-Ming Xia, and Fumio Hashinaga

Effects of flavonoid pigments on chlorophyll (Chl) degradation by Chl peroxidase in the flavedo of Wase satsuma mandarin (Citrus unshiu Marc. var. praecox Tanaka) fruits were studied. Chl was degraded when hydrogen peroxide was added in a reaction mixture containing Chl and a phosphate buffer extract from the flavedo. Chlorophyllide, which was formed by the action of chlorophyllase in the extract, was also degraded. The flavonoid contents decreased with the Chl degradation in the reaction mixture. Analysis of the flavonoid with HPLC showed that hesperidin and narirutin were contained in the flavedo as a major flavonoid, and that the former decreased significantly and the latter showed almost no change with the Chl degradation in the reaction mixture. In the ethylene-treated fruits, the hesperidin content in the flavedo also decreased with the degreening of stored fruits, suggesting that the flavonoid oxidation by Chl peroxidase could be involved in the Chl degradation.

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Ricardo Campos and William B. Miller

The relationship between the activity of soluble acid invertase and metabolism of soluble carbohydrates was investigated in snapdragon flowers. Flowers were harvested at three different developmental stages, and at four different dates. Soluble carbohydrates were extracted and analyzed by HPLC; invertase activity was determined in crude enzyme extracts. Sucrose concentration slowly increased throughout flower development from a closed bud to a fully open flower. Fructose and glucose concentration were relatively lower at the bud stage, increased during petal elongation, then slightly decreased at flower maturity. Mannitol concentration showed little change during flower development. An unknown compound increased in concentration during petal elongation and decreased at maturity. For all harvest dates, the specific activity of acid invertase increased with flower development. These results show a positive correlation of invertase activity and hexose sugars accumulation. It is possible that at maturity sugars are metabolized at a faster rate than produced, causing a slight decline in hexose sugars.

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Bhimanagouda S. Patil and Leonard M. Pike

The anti carcinogenic flavonol, aglycone, or free quercetin and quercetin glycoside content of seventeen onion varieties and 22 genotypes (Asgrow seed co.) and also 37 breeding lines (Texas A&M University) were analyzed by high performance liquid chromatography (HPLC). Quercetin glycosides were hydrolyzed into aglycones.

Total quercetin content in yellow and red onions varied from 80.34 to 286.4 mg/kg fresh weight in different varieties. Marked variation in total quercetin content between Texas A&M breeding lines (56-202 mg/kg fresh weight) and Asgrow breeding lines (54-287 mg/kg fresh weight) was observed. White onions contain trace amount of total quercetin. Free quercetin in Texas A&M breeding line 20272-G was 12.4 mg/kg fresh weight; however, other varieties and breeding lines contain negligible amount of free quercetin. It was concluded that the `designer' onion varieties with high quercetin content for health consciousness can be produced.