University of North Florida
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Stuart Chalk, Ph.D.
Department of Chemistry
University of North Florida
Phone: 1-904-620-1938
Fax: 1-904-620-3535
Website: @unf

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Classification: Fruit -> grape

Citations 4

"Flow Injection Spectrofluorimetric Determination Of Ethylenethiourea"
Fresenius J. Anal. Chem. 1998 Volume 362, Issue 4 Pages 399-403
Tomás Pérez-Ruiz, Carmen Martínez-Lozano, Virginia Tomás, Antonio Sanz, Jesús Martín

Abstract: A flow injection configuration is proposed for the fluorimetric determination of ethylenethiourea. The procedure is based on the inhibitory effect of ethyl-enethiourea on the oxidation of thiamine to thiochrome by Hg(II). A linear calibration graph was obtained between 0.1-2.0 µg mL-1, with a sampling rate of 40 samples/h and a relative standard deviation of 1.11%. The usefulness of the method was tested for the determination of ethylenethiourea residues in water, milk, potatoes, pear, grape, and apple.
Ethylenethiourea Fluorescence Indirect

"Effect Of Nitrogen Application Timing On N Uptake By Vitis Labrusca In A Short-Season Region"
Am. J. Enol. Vitic. 2004 Volume 55, Issue 3 Pages 246-252
Randall J. Vos, Thomas J. Zabadal, and Eric J. Hanson

Abstract: Fertilizer nitrogen (N) was applied to Vitis labrusca L. cvs. Niagara and Concord grapevines in Michigan at various times to determine its effect on soil N levels and fertilizer N recovery in vine tissues. Labeled ammonium nitrate (15NH415NO3) was applied to the soil beneath vines at a rate of 68 kg N/ha at different times between budbreak and six weeks after bloom. Soil was sampled at one-to two-week intervals after the fertilizer applications to follow the inorganic soil N dynamics. Vines were excavated at the time of commercial grape harvest to quantify fertilizer N recovery. All times of fertilizer application resulted in less than 20% uptake of the N applied. Vines fertilized at budbreak generally contained less fertilizer N and allocated a greater fraction of the fertilizer N to fruit and leaves than later times of application. Vines fertilized later in the season absorbed more fertilizer N and allocated more of it and total N to the roots than earlier times of application. Later applications resulted in more fertilizer N remaining in the top 90 cm of soil at the end of the season. Based on these findings, N application to vineyards in this short-season region was more efficient between bloom and six weeks after bloom than at budbreak.
Nitrogen Ammonium, nitrogen Timed injection

"Effect Of Nitrogen Fertilization On Growth, Canopy Density, And Yield Of Vitis Vinifera L. Cv. Cabernet Sauvignon"
Am. J. Enol. Vitic. 1999 Volume 50, Issue 3 Pages 351-358
Sally-Jean Bell and Alan Robson

Abstract: The effect of nitrogen supply on the vegetative and reproductive capacity of vines of low nitrogen status was investigated in a field trial conducted in Western Australia. Five rates of nitrogen fertilizer (0, 50, 100, 200, and 400 g N/vine) were applied to irrigated, 12-year-old Cabernet Sauvignon vines over three seasons. Two-thirds of the nitrogen was applied late budbreak and the rest at two weeks after flowering. Moderate rates of nitrogen fertilization stimulated vine growth and vigor (shoot extension rate) resulting in an increase in canopy density. Prior to flowering, maximum vine vigor was observed upon addition of 100 g N/vine. This effect was no longer evident after flowering. Those vines supplemented with 100 g of nitrogen also achieved maximum petiole nitrate concentrations at flowering, growth (shoot length, pruning weight, and leaf area), and canopy density (leaf layer number). Vines receiving 400 g N/vine had shorter shoots and less pruning weight than vines receiving 100 g N/vine, as vigor did not respond to nitrogen fertilizer prior to flowering. However, the petiole nitrate concentration, total leaf area, and canopy density of vines supplied with 200 to 400 g N/vine were no different to those vines supplemented with 100 g N/vine. Nitrogen had no effect on the total vine yield in the first and last season. However, the highest yield came from vines receiving 100 g N/vine in the second season. Additional applications of 200 g and 400 g N/vine increased the yield no further. Higher berry numbers per bunch were associated with the increase in total vine yield. It appeared that moderate rates of nitrogen fertilization can have a beneficial effect on vine productivity in situations where vine nitrogen status is low. In contrast, excessive nitrogen fertilization was an unprofitable exercise as it provided no further benefits in terms of vine productivity.
Nitrogen Nitrate

"Effect Of Nitrogen Fertilizer Timing And Rate On Inorganic Nitrogen Status, Fruit Composition, And Yield Of Grapevines"
Am. J. Enol. Vitic. 1994 Volume 45, Issue 4 Pages 377-387
L. Peter Christensen, Mary L. Bianchi, William L. Peacock, and Donna J. Hirschfelt

Abstract: A four-year (1987-90) trial was conducted to study the effects of timing and rate of N fertilizer application on furrow-irrigated Barbera, Grenache, French Colombard, and Chenin blanc grapevines. The objectives were to further determine optimum N fertilizer practices for important wine cultivars in the San Joaquin Valley and to compare inorganic N constituents, NO3--N and NH4+-N, for N status determination. The six treatments included four N fertilizer application timings at budbreak (BB), fruit set (FS), veraison (V), and post-harvest (PH) with a 56 kg N/ha rate, as well as BB with a 2X rate of 112 kg N/ha and control (C0). Vine N status was determined by NO3--N and NH4+-N levels and their sum, total inorganic N (TN), in bloom and veraison petioles. Yield and fruit composition parameters were measured for vine response. Cultivar responses varied widely, with Grenache and Barbera being the high and low extreme cultivars, respectively, in petiole TN status and responsiveness to N treatment; French Colombard and Chenin blanc were intermediate. Generally, TN status increased with increasing N rate (C0 bull BB56 bull BB112). Nitrogen fertilizer timing demonstrated that the more recent N applications often resulted in a higher petiole TN status at the next petiole sampling; i.e., PH56 and BB56 treatment petioles had higher TN status at bloom while FS56 was higher at veraison. Post-harvest timing was found to be particularly effective in supplying petiole TN in the spring; i.e., PH56 sometimes resulted in bloom petiole TN levels comparable to BB112 in all four cultivars and higher than BB56 in Grenache, French Colombard, and Chenin blanc. Petiole NO3--N levels were more sensitive than NH4+-N levels to fertilizer treatment. The greater contribution of NO3--N to TN and their high correlation coefficients as compared to NH4+-N and TN would place in question the utilization of NH4+-N as an additional measurement of N status. Grape soluble solids was the most responsive fruit parameter to N treatment. Generally, N fertilizer decreased soluble solids over C0, irrespective of timing, and with the highest rate (112 kg N/ha) resulting in the largest decrease. Grape yields were only affected in Grenache, with all of the N treatments increasing yields over C0 except V56. This result, plus other negative effects of the V56 treatment, suggest that veraison was the least desirable timing of those compared. Otherwise, timing effects on fruit parameters were minor.
Nitrogen Nitrate Ammonium Nitrogen, total Optimization