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Olanike O. Onayemi, Catherine C. Neto, and Justine E. Vanden Heuvel

The effect of partial defoliation (rate and timing) on vine carbohydrate concentration and the development of phenolic compounds in field-grown `Stevens' cranberry fruit was investigated in two experiments. In Expt. 1, partial defoliation rates of 0%, 18%, 39%, and 53% of total leaf area were applied before new growth, at fruit set, at midfruit development, and preharvest. In Expt. 2, treatments of 0% and 34% removal of new leaves were applied at postfruit set, and at midfruit development. In both experiments, upright samples were harvested for carbohydrate analysis 10d after defoliation, and fruit were removed for analysis before commercial harvest of the site. While total berry phenolic concentration was unaffected by partial defoliation in both studies, the separate pools of flavonoid compounds were affected differently by treatment. In Expt. 1, total flavonol concentration at harvest was improved by the highest rate of partial defoliation (53% of total leaf area) at both fruit set and midfruit development. Total anthocyanin concentration was improved by partial defoliation rates of 39% and 53% of total leaf area compared to the 18% defoliation treatment, but was not affected by timing of defoliation. Pearson correlation coefficients indicated that total flavonol concentration was positively correlated with vine total nonstructural carbohydrate concentration at preharvest, while total anthocyanin concentration was negatively correlated with vine soluble carbohydrates, starch, and total nonstructural carbohydrate concentration at midfruit development. In Expt. 2, total phenolics, flavonols, and anthocyanins were unaffected by partial defoliation; however there was a negative correlation between total anthocyanin concentration in the fruit and soluble carbohydrate concentration in the vine at midfruit development. In these experiments, partial defoliation early in the growing season improved total flavonols and total anthocyanins. Production of flavonols and anthocyanins appeared to be regulated independently of each other.

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Justine E. Vanden Heuvel and Joan R. Davenport

Five fertilizer treatments were applied to a `Stevens' cranberry bed in a 3-way split application (roughneck, 75% bloom, and 3 weeks after bloom) in Spring 2004 at State Bog in E. Wareham, Mass. Nitrogen rates were 0, 22, 45, 67, and 90 kg/ha; P was applied at 22 kg/ha, and K at 44 kg/ha. At mid-fruit development and again at preharvest, 20 vegetative and 20 fruiting uprights were collected from each plot in mid-morning. The N concentration per upright increased linearly with increased N application. Increased upright N concentration had no effect on soluble carbohydrate (sucrose + glucose + fructose) concentration, but decreased starch concentration, more so in vegetative uprights than in fruiting uprights on both sampling dates. Total nonstructural carbohydrate concentration (TNSC) was negatively impacted by increased N in vegetative and fruiting uprights at mid-fruit development, but N did not impact TNSC in either type of upright by harvest. Vegetative uprights contained greater concentrations of N, soluble carbohydrates, starch, and TNSC at both sampling dates, but contained lower concentrations of chlorophyll A and chlorophyll B.

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Marianna Hagidimitriou and Teryl R. Roper

Fruit set has been shown to be a major limiting factor in cranberry (Vaccinium macrocarpon Ait.) productivity. Total nonstructural carbohydrate (TNC) content is lowest during the flowering and fruit set period. This research was undertaken to determine the potential sources of carbohydrates which are important to support fruit set and fruit growth in cranberry. Fruiting uprights had lower TNC content than vegetative uprights beginning at early bloom and continuing through harvest, largely due to lower starch content. Starch from fruiting uprights is apparently remobilized to support flowering and fruit set. This also suggests that uprights on which the fruit are borne are the primary source for carbohydrates for fruit set and fruit growth throughout the season. Net CO2 assimilation rates (NAR) were measured in the field on current season and one year old leaves on cranberry uprights. New leaves had higher NAR than one year old leaves throughout the season. Thus, newly formed leaves on uprights, appear to be an important source for carbohydrates for fruit set and fruit growth. On a diurnal basis NAR peaked at approximately 9:00 a.m. and gradually declined through the day.

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Muntubani D.S. Nzima, George C. Martin, and Chic Nishijima

Early fall (September) defoliation and late spring (early June) shading of “off” and “on” pistachio trees were used to test two hypotheses: that 1) fall defoliation would reduce carbohydrate storage sufficiently to suppress spring growth and 2) spring shading would reduce carbohydrate status and increase inflorescence bud abscission. Defoliation suppressed initial leaf area expansion the following spring on current year shoots of “off” but not “on” trees respectively. Suppression of leaf size was correlated with the initial low concentration of carbohydrates in organs of individual branches of the tree. Fruiting and artificial shading in June had more dramatic effects on growth parameters than defoliating. Shading “off” trees for 14 days in early June accelerated abscission of inflorescence buds, reduced dry mass of individual leaves, buds, current year and 1-year-old shoots. Shading also reduced the concentration of total nonstructural carbohydrates (TNC) of these organs in “off” and “on” trees. Fruiting suppressed leaf size and leaf dry mass by 20% and 30% among individual branches of undefoliated and defoliated trees respectively. Low carbohydrate concentrations in individual branches and inflorescence buds following shading were closely correlated with the abscission of inflorescence buds.

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Michelle R. Botelho and Justine E. Vanden Heuvel

American cranberry (Vaccinium macrocarpon) production sites are often flooded for pest control and crop harvest. However, little is known about how this practice affects vines. A survey was conducted in Massachusetts over a 3-year period to determine the effect of spring, fall, and winter floods on total nonstructural carbohydrate concentration (TNSC) of cranberry uprights of four cultivars. With a few exceptions, TNSC generally was unaffected or increased during the course of the 1-month “late water” flood held from mid-April to mid-May. The 48-hour “flash” flood, held in mid- to late May, generally had little effect on vine TNSC. Fall “harvest” floods, which ranged in duration from 3 to 27 days, often resulted in a decrease in TNSC, with greater decreases in TNSC occurring in early fall floods compared to late fall floods. Decreases in TNSC during the harvest flood were as great as 42%. “Winter” floods had little effect on TNSC. Path coefficient analysis indicated that flood duration, date of application, water temperature, and dissolved oxygen concentration all impacted vine TNSC during the flood, while floodwater depth had little effect. Water clarity (i.e., light penetration to the vines during the flood) also appeared to have little impact. Due to the frequent observation of TNSC decline during fall flooding, it is possible that yield potential of cranberry vines is reduced by current flooding practices.

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Teryl R. Roper, John Klueh, and Marianna Hagidimitriou

Cranberry (Vaccinium macrocarpon Ait.) vines were shaded with either 72% or 93% shadecloth (28% or 7% of full sun) for 1 month before flowering, after flowering, or before harvest. Fruit set was reduced by heavy shade (93%) before flowering in 1991 but not in 1992 or 1993. Heavy shade following flowering reduced fruit set in 1991 and 1992 but not 1993. The number of flowers per upright was generally not affected by shading but was reduced by prebloom shading at either level in 1993. Mean berry weight was usually conserved. Yield was reduced by shading at either level following flowering in 1991 and 1992. Shading just before harvest had no effect on the characteristics measured. Total nonstructural carbohydrate concentration was reduced to about half relative to the controls by either shading level at all treatment dates. Carbohydrate concentrations recovered to control levels by 4 to 8 weeks following removal of shading. Shading always reduced carbohydrate concentrations but did not always reduce fruit set or yield.

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J.M. Goatley Jr., V.L. Maddox, D.L. Lang, R.E. Elmore, and B.R. Stewart

The ability of a temporary turf cover and foliar-applied iron (Fe) to sustain or promote bermudagrass (Cynodon dactylon (L.) × transvaalensis Burtt-Davy `Tifway' growth beyond its normal growing periods in central Mississippi was evaluated during the fall, winter, and spring seasons of 1998-2001. The application of a polypropylene turf blanket when night temperatures were predicted to be ≤4 °C extended acceptable bermudagrass turf quality by 5 to 8 weeks in the fall and winter period as compared to the uncovered control plots. Also, complete green-up of the turf occurred 4 to 6 weeks earlier the following spring. There was no enhancement in bermudagrass quality by temporarily covering at predicted night temperatures of ≤15 or ≤9.5 °C. Foliar applied iron (Fe) further enhanced turf quality in the fall and winter months, but resulted in no visible turf response the following spring. Total nonstructural carbohydrate (TNC) concentrations in rhizomes that were sampled during November, January, and April 2000 and 2001 were generally increased by the cover application as compared to the uncovered control. Foliar Fe applications did not influence TNC levels.

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Michelle R. Botelho and Justine E. Vanden Heuvel

Cranberry production involves the use of flooding for several purposes during the growing season, including pest control, winter protection, and harvest. The effect of the dissolved oxygen concentration in floodwater on carbohydrate concentration of uprights and roots during flooding was investigated using potted `Stevens' cranberry (Vaccinium macrocarpon Ait.) vines. Pots were placed in large bins filled with water to simulate a spring pest control flood (called late water) over a 21-day period. Two treatments were applied: oxygenated and nonoxygenated (control). Uprights and roots were collected every 3 days and prepared for HPLC analysis to quantify nonstructural carbohydrate concentration. Soluble sugar (sucrose, glucose, and fructose) and starch concentration, as well as total nonstructural carbohydrate (TNSC) concentration, decreased over the 3-week period in uprights but not roots regardless of treatment. Interestingly, the sucrose, glucose, fructose, and starch concentrations of uprights in the oxygenated treatment were lower than those of uprights in the control treatment throughout the experiment. This research indicates that vines in flooded bogs demonstrate a net carbon loss, resulting in reduced carbohydrate concentration available for growth and fruit production.

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Karen L.B. Gast and Melinda McMillan

Peony flowers are among the few fresh-cut flowers that can be stored dry at cold temperatures for weeks and still produce a viable product for the marketplace. Devising new ways to extend that storage period could open new markets for peony growers. In the northern hemisphere, more peonies could be available for summer weddings, and in the southern hemisphere, red peonies could be used for Valentine's Day. Being able to control and extend the vaselife of peony flowers could also be useful for companies that freeze-dry peonies. Their production is limited by the length of their processing cycle and the size of their freeze dryer. Being able to extend their production season could make them more profitable. Three treatments were applied to peony flowers harvested in the colored bud stage before flowers where placed in cold storage, 2°C. An untreated control was included. Flowers were removed from storage every 2 weeks for 14 weeks. Vaselife and fresh weights were evaluated. Total nonstructural carbohydrate levels of the petals, leaves, and stems of the flowers are to be analyzed. Preliminary analysis of the data shows some treatment differences.

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Patricia Sweeney, Karl Danneberger, Daijun Wang, and Michael McBride

Limited information is available on the performance under temperate conditions in the United States of recently released cultivars of creeping bentgrass (Agrostis stolonifera L.) with high shoot density for use on golf course putting greens. Fifteen cultivars were established in Aug. 1996 on a greens mix with high sand content to compare their seasonal weights and total nonstructural carbohydrate (TNC) contents. The cultivars were maintained at 3.1 mm height of cut. Shoot density counts were taken during Apr., July, and Oct. 1998. Root weights and nonstructural carbohydrate levels were assessed monthly from June 1997 through Nov. 1998. A cultivar group contrast between the high shoot density cultivars (`Penn A1', `Penn A2', `Penn A4', `Penn G1', `Penn G2', and `Penn G6') and the standard cultivars (`Penncross', `Crenshaw', `Southshore', `DF-1', `Procup', `Lopez', `SR1020', and `Providence') revealed that the former averaged 342.9 and 216.1 more shoots/dm2 on two of the three sampling dates. Root dry weights did not vary significantly (P ≤ 0.05) among the cultivars. Performing a contrast between new high shoot density cultivars and standard cultivars revealed greater root dry weight in the former during Mar. and May 1998. Differences (P ≤ 0.05) in TNC were observed on two of the 18 sampling dates, but no trends were evident.