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Ken Takahata and Hiroyuki Miura

water to the upper parts of the shoots, which accelerates a reduction in the moisture content of the shoot. In this article, we studied whether a prototypic method called “basal wire coiling” could increase the sugar concentration in tomato fruit juice

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Wesley Gartner, Paul C. Bethke, Theodore J. Kisha, and James Nienhuis

, developmental differences can affect sugar concentrations and relative amounts of individual sugars found in vegetables and specific vegetable tissues ( Hounsome et al., 2008 ; Lee et al., 1970 ). Regardless of the tissue type, sugar concentrations are cultivar

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Charles S. Vavrina and Doyle A. Smittle

Six onion (Allium cepa L.) cultivars were grown during 2 years to evaluate the effects of environment on bulb quality as measured by sugar and pyruvate (pungency) concentrations. Within each year, bulb fresh weight was not affected by cultivar; however, bulb fresh weights were 36% higher in a year when most of the rain fell during maximum bulb expansion. Total bulb sugar concentration and pungency varied among cultivars and years. Pungency was higher and the sugar: pungency ratio was lower in `Texas 1015Y' and `Sweet Georgia' than in `Dessex', `Rio Bravo', 'Hybrid Yellow Granex', and `Granex 33'. Under low S nutrition, market acceptance of “sweet” onion cultivars that vary slightly in nonstructural water-soluble carbohydrates may be assessed more precisely by the sugar: pungency ratio than by sugar or pungency assessments.

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F. Kultur, H.C. Harrison, and J.E. Staub

Muskmelon (Cucumis melo L.) genotypes, Birdsnest 1 [`Qalya' (BN1)], Birdsnest 2 (BN2), and `Mission' (V) were used to determine the effects of differing plant architecture and spacing on fruit sugar concentration and yield. The BN1 and BN2 genotypes possessed a highly branched growth habit specific to birdsnest melon types, but not characteristic of standard indeterminate vining types (e.g., `Mission'). Experiments were conducted at both the Hancock and Arlington Experimental Farms in Wisconsin, where plant response to two within-row spacings [35 cm (72,600 plants/ha) and 70 cm (36,300 plants/ha)] in rows on 210-cm centers was examined. Genotypes were grown in a randomized complete-block design with four replications at each location and evaluated for primary lateral branch number, fruit number per plant and per hectare, average fruit weight, yield per plant (g), yield per hectare (t), and fruit sugar concentration. Yield, fruit number, and sugar concentration were higher for all genotypes at Arlington than at Hancock. The main effect of genotype was significant for all traits examined. Genotypes BN1 and V had higher mean fruit weight, yield per plant and per hectare, and fruit quality (fruit sugar concentration) than did BN2. Spacing affected all traits, except primary branch number and fruit sugar concentration. Fruit number and yield per plant and average fruit weight were higher with wider spacing, but yield (t·ha-1) and fruit number per hectare were lower.

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T. Casey Barickman, Thomas E. Horgan, Jennifer R. Wheeler, and Carl E. Sams

, increased fruit tissue firmness, and elevated soluble sugar concentrations in apple ( Malus × domestica ) fruit tissue ( Nava et al., 2008 ). However, contrasting results have been indicated in previous research. For instance, Fallovo et al. (2009a

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Richard J. Campbell, Richard D. Fell, and Richard P. Marini

Flowering spurs located at interior and exterior canopy positions of `Stay-man' and `Delicious' apple (Malus domestics Borkh.) trees were girdled and/or defoliated to determine the influence on nectar production and composition. Nectar volume was less at exterior than interior canopy positions for `Delicious', but not for `Stayman'. Girdling suppressed nectar production by 92% and reduced the sugar concentration of the remaining nectar. Defoliation of nongirdled spurs had no effect on nectar sugar concentration, but defoliation of girdled spurs reduced nectar sugar concentration by 24%. Relative percentages of sucrose, glucose, and fructose, and the sucrose: hexose ratio were unaffected by any treatment. Nectar production of nongirdled spurs did not depend on the presence of spur leaves.

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S. Wolf, Y. Lensky, and N. Paldi

Fruit and seed set in insect-pollinated agricultural crops rely primarily on honeybees because of their ease of management and transportation. In many fruit and vegetable crops, the number of bee visitations can be the limiting step in obtaining optimal yield. Increasing the attractiveness of flowers to honeybees could, therefore, provide a useful means of improving fruit yield and seed production. Genetic variability in attractiveness to honeybees was found within the genus Citrullus. The number of daily visits per flower ranged from six to 12 among cultivars. Moreover, most of the visits to the more attractive cultivars occurred in the first hour of bee activity, whereas visits to the less attractive cultivars started later in the morning. A positive relationship was found between the frequency of bee visitations and seed number per fruit. Analyses of floral attributes indicated no genetic variability in flower size, amount of pollen grains, or nectar volume; however, differences were observed in the concentration of sucrose and total sugars in the nectar. A positive relationship was found between attractiveness to bees and nectar sugar concentration, suggesting that this characteristic is one of the parameters responsible for variability in attractiveness to honeybees.

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T.J.K. Radovich*, M.D. Kleinhenz, J.G. Streeter, and M.A. Bennett

Cabbage (cv. Bravo) was grown in 2002 and 2003 at The Ohio State Univ., Ohio Agricultural Research and development Center in Wooster, Ohio. The four irrigation treatments, arranged in a RCB design, were: 1) irrigation throughout development [no stress (NS)], 2) irrigation only during head development [frame stress (FS)], 3) irrigation only during frame development [head stress (HS)], and 4) no irrigation [frame and head stress (FHS)]. Irrigation timing relative to crop stage significantly affected all head characteristics except density, with the greatest differences between cabbage receiving irrigation during head development (NS, FS) and cabbage not irrigated during head development (FHS, HS). On average, heads from NS and FS plots were heavier (38%), larger (15%), less pointed and had less volume occupied by the core than heads from HS and FHS plots. Combined head fructose and glucose concentrations were significantly greater in cabbage receiving irrigation during head development than in cabbage not irrigated during head development (47% vs. 41% dwt, respectively). Sucrose concentrations were significantly greater in cabbage not irrigated during head development than cabbage receiving irrigation during head development (8% vs. 6% dwt, respectively). The higher ratio of sucrose: fructose+glucose observed in HS and FHS relative to NS and FS treatments was interpreted as an osmo-regulatory response with potential implications for cabbage flavor. Overall, it was concluded that physiological responses elicited in cabbage by differential irrigation can affect important head traits, and that targeted applications of water during specific stages of crop development may be utilized to maximize water use efficiency and crop quality.

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Nicky G. Seager and Roger M. Haslemore

Experiments investigating kiwifruit [Actinidia deliciosa (A. Chev) C.F. Liang et A.R. Ferguson var. deliciosa] maturation were undertaken requiring the determination of total soluble sugar (TSS) and starch concentrations in numerous fruit samples. The phenol-sulfuric acid assay was judged to he a convenient method for determining TSS from tissue extracts and gave results similar to those obtained by high-pressure liquid chromatography. The starch procedure adopted involved gelatinizing fruit tissue using hot water and a thermostable α -amylase (Termamyl); hydrolizing starch using amyloglucosidase; and determining glucose using glucose oxidase. The methods enabled one person to analyze up to 40 kiwifruit samples for TSS and starch concentrations during 9 hours and likely will be applicable to research concerning fruit development and maturation.

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N. Georgelis, J.W. Scott, and E.A. Baldwin

Small-fruited cherry tomato accession PI 270248 (Lycopersicon esculentum Mill. var. cerasiforme Dunal) with high fruit sugars was crossed to large-fruited inbred line Fla.7833-1-1-1 (7833) that had normal (low) fruit sugar. Sugars in the F2 were positively correlated with soluble solids, glucose, fructose, pH, and titratable acidity, and inversely correlated with fruit size. Earliness was not significantly correlated with sugars but was negatively correlated with fruit size. Thus, the lack of a sugar-earliness correlation indirectly indicates a trend for early tomato plants to be lower in sugars than later maturing plants. Sugars were not correlated with yield or pedicel type. Fruit from indeterminate plants had significantly more sugars than from determinate plants. Six random amplified polymorphic DNA (RAPD) markers linked to high sugars were found, five dominant (OPAE 4, UBC 731, UBC 744, UBC 489, UBC 290) and one co-dominant (UBC 269). Five of the markers were also linked to small fruit size and one of these also was linked to low yield (UBC 290). The sixth marker (UBC 269) was linked to indeterminate plant habit. UBC 731, UBC 489, and possibly OPAE 4 were in one linkage group, while UBC 744 and UBC 290 were in another linkage group. Combinations of all the markers together explained 35% of the sugar variation in the F2 grown in Spring 2002.