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  • Author or Editor: T. G. McCollum x
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The objective of this work was to determine if lipid composition of grape fruit flavedo tissue differed with canopy position and if changes in flavedo lipid composition occurred during the development of chilling injury (CI). `Marsh grapefruit were harvested from interior (IN) and exterior (EX) canopy positions and stored at 5C for up to 8 weeks. During storage, EX fruit developed severe CI, whereas IN fruit developed only trace CI. Electrolyte leakage from EX fruit flavedo increased during storage and significantly greater than from IN fruit At the time of harvest, flavedo oleate and linoleate, on a μg % basis, were higher in IN than in EX fruit During storage at 5C, the amount of oleate in IN fruit flavedo decreased and was similar to EX fruit after 4 weeks at 5C. The relative amount of flavedo linoleate decreased in IN fruit and increased in EX fruit during storage at 5C and following 8 weeks at 5C was higher in EX fruit than in IN fruit At the time of harvest, total lipid P in flavedo was higher in IN fruit than in EX fruit; during storage the amount of flavedo lipid P in IN fruit decreased and was equivalent to EX fruit following 8 weeks at 5C. Total sterols in flavedo did not differ with canopy position and remained constant during storage.

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Four asparagus (Asparagus officinalis L.) cultivars, UC 157, Syn 4-56, Mary Washington, and Viking KB3, were stored at 2C, and their quality was evaluated during 3 weeks of storage, There were no cultivar differences in respiration, weight gain, or soluble solids concentration initially or after storage. After 3 weeks of storage, the cultivars UC and S4 were more vividly green and less seedy than MW or VK, but UC exhibited slight to moderate chilling injury. Spears of S4 and VK had better overall appearance than MW or UC.

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Chitinases (EC 3.2.1.14) and β-1,3-endoglucanase (EC 3.2.1.39) are enzymes that are believed to be components of a plant's natural defense against fungal pathogens. We are interested in the potential role of these enzymes in citrus decay resistance. In our preliminary work, we have determined the activities of chitinases and β-1,3-endoglucanases in the flavedo of grapefruit (Citrus paradisi cv. Marsh) at 17 times during the course of fruit development. Chitinase activity is initially high in flavedo, but drops rapidly and is low, although fairly constant, throughout the remainder of fruit development. In contrast to chitinase, β-1,3-endoglucanase activity is lowest in young fruit and increases during development. Western blots of crude flavedo extracts following SDS-PAGE were probed with antibodies raised against purified citrus chitinase and glucanase, and results revealed that changes in the activities of chitinase and β-1,3-endoglucanase were reflected in the amount of chitinase and glucanase protein present in the extracts. Partial purification of flavedo chitinases and glucanases revealed that acidic and basic forms of both enzymes were present in the extracts, although the basic forms were predominant.

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Calabaza is a pumpkin-like fruit that is grown throughout the tropics and subtropics. In the Caribbean “calabaza” is used in soups and other traditional dishes. In Puerto Rico, the 1987-88 calabaza crop was worth $8 million and the value of the crop in Florida is estimated to exceed $5 million. Mainland production of tropical calabaza types of C. moschata is limited largely to Florida where it is used mostly by those of Cuban descent. Despite the popularity and commercial significance of calabaza, little effort has been directed toward the study of cultural practices or varietal improvement. Only two improved varieties, `Borinquen' introduced by the Puerto Rico Agricultural Experiment Station in the 1940s and `La Primera' introduced by the Florida Agricultural Experiment Station in 1979 are available. Approaches to calabaza improvement including development of plants with shorter vines, incorporation of powdery mildew resistance, and production of uniform, symmetrical, hard-shelled, medium-sized fruit with enhanced nutritional quality in relationship to management systems are discussed.

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The fungicides thiabendazole (TBZ) or imazalil were applied at 1 g·liter-1 at 24 or 53C to `Marsh' and `Redblush' grapefruit (Citrus paradisi Macf.) to reduce fruit susceptibility to chilling injury (CI) and decay. Generally, there was more CI and decay on `Marsh' grapefruit than on `Redblush'. Severity of CI was lower in grapefruit that had been dipped at 53C than at 24C. Fruit dipped in fungicides had less CI than fruit dipped in water alone. Imazalil was more effective in reducing CI than TBZ. Fungicides reduced decay at both temperatures, and imazalil was better than TBZ. Chemical names used: 2-(4-thiazolyl)benzimidazole (thiabendazole, TBZ); 1-[2-(2,4-dichlorophenyl)-2-(2-propenyloxy)ethyl] -1H -imidazole (imazalil).

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The flowering habit and yield potential of seven calabaza [Cucurbita moschata (Duchesne), Poir.] genotypes were studied in the fall 1991 season. Earliest flowering and mature fruit were produced on bush plants developed from `Burpee Butterbush'. Time of flowering and distance from the crown was intermediate in time in the Florida developed varieties `La Primera' and `La Segunda' and latest in the Puerto Rican developed entries `Borinquen', Linea C Pinta, and Soler. Highest yields were produced by `La Primera' and `La Segunda', whereas, lowest yields were produced by the bush lines because of very small fruit size. Fruit size of `Borinquen' and Linea C Pinta was mostly in the desirable range of 2.3 to 4.5 kg. Most `La Primera' and `La Segunda' fruit were round, `Borinquen', Linea C Pinta, and Soler fruit were flat, and the bush lines produced variable shaped fruit. Further backcrossing to round types is required to overcome the problem of small fruit size and variable fruit shape in the bush lines.

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This study was conducted to determine rooting characteristics, root carbohydrate content, and performance of 10 bermudagrass [Cynodon dactylon (L.) Pers.] genotypes exposed to drought. A greenhouse study was conducted twice to determine root distribution and carbohydrate content throughout the soil profile during simulated drought stress. Root distribution among genotypes and accumulation of total nonstructural carbohydrate within roots differed with depths. Root mass at 30, 60, 90, and 150 cm was significantly correlated with turf quality during drought stress (r = 0.72, 0.86, 0.80, and 0.81, respectively) only for one of the two tests. Root carbohydrate distribution was not significantly correlated with turf quality for the selected bermudagrass genotypes.

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Fresh strawberries are highly perishable commodities, and berry quality at harvest delimits their potential shelf life. We are conducting harvest quality evaluations for seven commercially available cultivars. Seven different fruit characteristics were chosen to assess cultivar performance during the early, middle and late phases of the picking season: marketable berry yield, berry weight, berry firmness, berry color (“a” value), percept soluble solids, titratable acidity (percent citric acid) and the ratio between soluble solids and titratable acidity. Marketable berry yield, berry weight and berry firmness varied substantially between cultivars. A few differences were observed between cultivars for berry color. Berry flavor, as evidenced by the ratio between soluble solids and acidity, was also apparently different between cultivars with three of the seven cultivars consistently exhibiting higher ratios. The relationship of each measured parameter to quality will be discussed.

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