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associated with organic acids, bitterness is often the result of phenolic compounds, saltiness is attributable to sodium or potassium, and sweetness is the result of sugars, including fructose, glucose, and sucrose ( Sims and Golaszewski, 2003 ). Sugars not

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Abstract

The carbohydrate reserves in plant tissue have been correlated with all phases of plant growth and development. Consequently, several methods have been developed to quantify those reserves. The methods for starch determination are either direct (iodine staining) or indirect (the conversion of starch to sugars by chemical or enzymatic hydrolysis). Chemical methods involve hydrolysis of subunit bonds with either a strong acid or base, and enzymatic methods use catalytic proteins specifically to cleave the subunit bonds.

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Abstract

The pentose phosphate shunt (PPS) was shown to be active in roses (Rosa hybrida L.). The C6/C1 ratio indicated that possibly as much as 50% of the glucose oxidized in the rose flower is through the PPS. However, the activity of the PPS in relation to the Embden-Meyerhof-Parnas pathyway-tricarboxylic acid cycle (EMP-TCA) pathway did not change significantly throughout the cut life of the rose. There was a drop in the respiratory rate of petals throughout the cut flower life. The inner petals exhibited a consistantly higher respiratory rate than did outer petals regardless of whether the flower was kept in water or preservative.

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Abstract

The concentration of photosynthate in midribs of crisphead lettuce at various times of the day may be involved in the susceptibility of this crop to various postharvest disorders (3). Measuring the soluble solids content (SSC) of the juice expressed from midribs is simple when a hand-refractometer is used, and would be an ideal method for field use. However, lettuce is low in sugar content (5); thus, SSC may be no more of a valid measure of sugar content in lettuce than in cucumbers, which also have a low sugar content (4). Consequently, we adapted (1, 7) procedures for the determination of glucose, fructose, and sucrose, the principal sugars in head lettuce (type not specified, 5) to midribs of crisphead lettuce utilizing HPLC.

Open Access

The diurnal pattern of the activity of the starch synthesízing enzyme ADP-glucose Pyrophosphorylase was studied in young tomato seedlings, grown under a light/dark cycle of 12h/12h. The third leaf from the base of the plant was used for the study when they were 80 to 90% fully expanded. The enzyme activity had two peaks, a smaller peak during the light period and a larger peak during the dark period. The activity began to increase before the lights were turned on and it was maintained for the first four hours of the light period and then began to decline. Similarly, the activity began to increase again before the lights were turned off and remained high for the first four hours of the dark period.

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given a central role. Sucrose, fructose, glucose, and sorbitol are the most commonly used sugars used as carbon source and osmotic stabilizer ( Scozzoli and Pasini, 1991 ), although their concentration is more important for the osmolarity of the medium

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·L −1 sucrose, 20 g·L −1 fructose, or 20 g·L −1 glucose, alone or plus 200 mg·L −1 8-HQS; and distilled water as a control ( Table 1 ). These concentrations were chosen according to previous literature ( Ichimura and Korenaga, 1998 ; Islam et al

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Abstract

Four cultivars of cassava (Manihot esculenta Crantz), grown at 4 locations, were analyzed for root starch distribution. Starch and glucose variation among cultivars and locations indicated that both genetic and environmental factors were involved. Glucose content of all tissues sampled was less than 2%. The correlation between glucose and starch was negative in the parenchymatous and pith tissues for all cultivars except ‘HMC-2’. Location seemed to have little effect on starch concentration, which ranged from 23-33% in the central pith, 19-26% in the peel, and 34-44% in the parenchymatous tissue between the peel and the pith. The portion of the root closest (proximal) to the plant had a higher starch concentration than did the distal portion.

Open Access

Abstract

A method is described for determining glucose metabolism by the C-6/C-1 ratio. After an initial lag period to allow for equilibration of labelled glucose, an increase of accumulated 14CO2 in rose petals was linear with time. By taking the limit of the ratio of the C-1 and C-6 lines, one can arrive at the C-6/C-1 ratio as a ratio of the slopes of the lines. The slope of each of the lines can be calculated with 2 determinations within a relatively short time period. This method reduces metabolic recycling of the glucose and other problems associated with the traditional method of determining the C-6/C-1 ratio.

Open Access

a polymer of fructose with a terminal glucose moiety ( Chatterton et al., 1989 ). Increased catabolism and decreases in levels of fructans have been observed in grasses in response to defoliation ( Morvan-Betrand et al., 2001 ; Prud'homme et al

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