Developing Water Quality and Storage Standards for Cut Rosa Stems and Postharvest Handling Protocols for Specialty Cut Flowers.

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Title: Developing Water Quality and Storage Standards for Cut Rosa Stems and Postharvest Handling Protocols for Specialty Cut Flowers.
Author: Regan, Erin Matilda
Advisors: Dr. William Fonteno, Committee Member
Dr. Sylvia Blankenship, Committee Member
Dr. John Dole, Committee Chair
Abstract: Cut 'Freedom', 'Charlotte' and 'Classy' rose stems were subjected to various pH and EC solutions created by adding NaCl, Na2SO4, or CaCl2 to various base solutions: Floralife Professional; distilled water; or solutions of HCl, H2SO4, NaCl, Na2SO4, or NaOH. It was determined that the ideal laboratory solution has a low pH, 3.5 to 4.0, and an EC of 1.0 dS•⁻¹. The best salt to add is Na2SO4, but all tested salts provided acceptable results. The average vase life of cut Rosa stems placed in a 1.0 dS•⁻¹ vase solution was 13.9 d and the minimum, 5 d, was recorded for a 'Freedom' rose in either distilled water or a H2SO4 solution. Low pH solutions partially counteracted the negative effects of a high EC, but did not result in the longest vase life for the study. When vase life is plotted against EC, distilled water has a slope of -1.71, while HCl and H2SO4 have slopes of -0.84 and -0.21, respectively. The flatter slope of the acidic solutions indicates that the vase life of stems placed in a low pH solution did not decrease as EC increased as drastically as stems placed in water of a higher pH. In preliminary temperature studies, when using a standard mercury thermometer, 11, 13, or 14 h were required for a quarter, half, or full size box, respectively, to warm up from 3 to 23.8°C and twice as long for the same boxes to cool to 3°C. However, during a fluctuating temperature study using temperature data loggers, a half size box only required 4 h to warm up and 8.5 to 9 h to cool down. In a variable temperature study, the longest vase life, 15.3 d, was obtained when 'Freedom' stems remained in a 1°C cooler for 48 h, while the shortest vase life, 11.5 d, occurred when stems remained in a 20°C environment for 48 h. In a constant storage study, the longest vase life, 11.7 d, was obtained when 'Freedom' stems were placed in a 1°C cooler for 12 h. Vase life decreased linearly with both time and temperature to 6.4 d at 30°C for 36 h. 'Charlotte' stems also had the longest vase life, 8.6 d, at 1°C for 12 h, and shortest of 2.9 d at 30°C for 36 h. 'Classy' stems had the longest vase life, 9.3 d, at 1°C for 24 h, and shortest, 5.8 d, when held at 30°C for 48 h. In a National Cut Flower Trial Program, stems of promising cultivars were pretreated with either a commercial hydrating solution or DI water and placed in either a commercial holding solution or DI water. Over six years, the vase life of 88 cultivars representing 38 cut flower genera were tested. While there was cultivar variation within each genera, patterns of postharvest responses have emerged. The largest category, with 35 cultivars, were those that responded positively to a holding preservative; these cultivars were in the genera Acidanthera, Adenophora, Antirrhinum, Campanula, Capsicum, Celosia, Dianthus, Digitalis, Echinacea, Eustoma, Helianthus, Heptacodium, Heuchera, Leucanthemum, Lobelia, Physostegia, Rudbeckia, and Trachelium. Matthiola incana 'Vivas Blue' cut stems were harvested when at least one floret was open. Stems were unaffected by exogenous ethylene or anti-ethylene agents. Matthiola stems had a longer vase life when held dry as compared to being held in water and when stems were held for no more than 2 weeks. Hydrator and holding preservative combinations did not affect vase life; however, stems held in the cooler had a significantly longer vase life, ranging from 12.5 to 14 d, than stems that were not cold stored, which had a vase life of only 9.9 d. No significant differences in vase life, number of buds opened, or termination criteria occurred when stems were pulsed with 0, 10, or 20% sucrose. Stems had a longer vase life, 20.3 d, when placed in foam and a 2% sucrose solution as compared to 0, 1, or 4% sucrose in water. Regardless of foam use, as sucrose concentration increased, bud opening increased. Various commercial preservatives did not result in significant differences in vase life, number of buds open, or termination criteria. Vase life was longer, 12.1 to 13.0 d, when solutions were made from deionized water, regardless of the other additives than when the solutions were made from tap water, 11.3 d.
Date: 2008-06-08
Degree: MS
Discipline: Horticultural Science
URI: http://www.lib.ncsu.edu/resolver/1840.16/503


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