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Water plays a vital role in postharvest physiology of cut flowers. There are several factors affecting water uptake of cut flowers, including aspiration into the xylem and bacterial occlusion. While numerous studies have focused on water balance with cut flowers, few of them have focused on cut Lilium. After harvest, cut lilies encounter discontinuous water uptake, and the duration of exposure in air varies depending on the handling procedure. The critical duration of desiccation that would cause irreversible damage to lilies is still unknown. Furthermore, commercial lily growers have questioned the necessity of cleaning buckets to reduce bacteria and microbial building in holding solutions. In this dissertation, a variety of approaches were used to address these factors and how they affect lily postharvest quality. We investigated the effect of exposure time in air. Lilies had some rehydration ability after holding in air for 24 h, but longer exposure time reduced total water uptake and postharvest quality. The research target then shifted to microbial effects on water uptake and quality. The cumulative water absorption and flower diameter were negatively correlated to bacterial numbers in water and the exposure time in bacterial water. Bacterial concentrations of 107 cfu·mL-1 (colony forming unit per mL) caused inferior postharvest quality. The abundance of bacteria was greatest in the lower stem, especially in the lowest 15 cm. By using 16S rRNA gene sequencing, we found different flowers (rose, lily, and gerbera) affect the composition of microbial community, and the diversity of microbial communities increased over time in the vase period. In addition, bacterial taxa and chloroplast as well as mitochondria showed dynamic changes of relative abundance over time as well. We conclude the duration that cut lilies are exposed to dry, non-refrigerated conditions should be kept as short as possible. While a real financial cost, buckets should be regularly cleaned, and water replaced frequently to avoid microbial build-up. Finally, the sequencing work revealed the complexity and dynamics of the microbiome in a cut flower vase and highlights the limited information of vase microbiology the industry currently has.

Harvest timing of apples, an important factor determining fruit quality after storage, is often based on maturity assessments that include the starch pattern iodine (SPI) test. The SPI test provides a visual indicator of starch degradation in the equatorial region of the fruit. SPI and starch concentrations in apple cultivars, and the effects of factors such as aminoethoxyvinylglycine (AVG) and 1-methylcyclopropene (1-MCP), have been investigated. SPI values increased as starch concentrations declined in 'Gala, 'Honeycrisp', 'McIntosh', and 'Empire' apples during maturation. The two factors have a curvilinear relationship for all cultivars. Declines in percentage of amylose were found to be linear and cultivar dependent. Computer-based image analysis of SPI-based staining revealed a wide range of values, and a linear correlation was found between SPI value and percentage stained area. Starch concentrations in stem-end tissues were lower than in equatorial and calyx-end tissues of 'Empire' and 'Gala' apples. AVG and 1-MCP applied preharvest to inhibit ethylene production and perception, respectively, had cultivar as well as application timing-dependent effects on maturation. Effects of these treatments on starch degradation were limited in both 'McIntosh' and 'Empire' fruit. Weak correlations were found for 'Empire' apples between harvest indices and differences in absorbance (IAD) readings, which reflect chlorophyll concentrations in the skin. However, preharvest treatment of fruit with AVG and 1-MCP altered the relationships between IAD and other harvest indices, especially the internal ethylene concentration (IEC). 'Empire' apples are susceptible to firm flesh browning when stored at temperatures close to 0 °C, or after treatment with postharvest 1-MCP. This storage disorder causes major losses for the apple industry every year and no storage regime has been found so far to alleviate the problem. A full economic analysis indicated that there is an economic tradeoff between harvest date, occurrence of flesh browning, and likely net profits. Overall maturity assessment at harvest could be used as an indicator for storage disorders and/or storage length if factors such as differences in fruit maturation between cultivars and within the fruit are better understood.

United States ornamental plant producers imported approximately $61 million worth of unrooted cuttings in 2006. The top three greenhouse production crops geraniums (Pelargonium L'Hér. ex Ait.), poinsettias (Euphorbia pulcherrima Willd. ex Klotzsch) and New Guinea impatiens (Impatiens hawkeri W. Bull) had a wholesale value of $330 million and were produced from approximately 138 million cuttings. Understandably, improving cutting quality by reducing losses induced by ethylene exposure and shipping damage is an area of active research. To investigate possible areas for improvement in cutting production and shipping we studied the use of ethephon, [(2-chloroethyl) phosphonic acid] in stock plant management, 1-methylcyclopropene (1-MCP) use as an ethylene inhibitor of unrooted cuttings, and modified atmosphere (MA) storage of unrooted cuttings. Application of 700 mL • L-1 1-MCP prior to ethylene treatment prevented ethylene damage to Begonia hybrida 'Anita Louise', Portulaca oleracea L. 'Sleeping Beauty' and Lantana camara L. 'Patriot Sunbeam'. Also, 700 mL • L-1 1-MCP application to poinsettia 'Visions of Grandeur', impatiens 'Sonic Red', geranium 'Rocky Mountain White', Pelargonium peltatum (L.) L'Hérit. 'Mandarin', Petunia x hyrbrida 'Suncatcher coral prism' cuttings caused significant ethylene generation. 1-MCP application reduced geranium' Kardino' root numbers and delayed adventitious root formation of Angelonia angustifolia Benth. 'Carita Lavender', Calibrachoa x hybrida Llave & Lex. 'Terra Cotta', I. hawkeri 'Sonic Red', Portulaca oleracea L. 'Fairytales', Sutera cordata Kuntze 'Abunda Blue Improved' and Verbena x hybrida Groenl. & Ruempl. 'Aztec Wild Rose', though 1-MCP rooting effects were overcome by subsequent immediate exposure to ethylene. Ethephon is used to increase stock plant branching and sink tissues abscission. Ethylene evolution from cuttings harvested from recently treated stock plants is suspected to cause leaf abscission of unrooted cuttings during shipping. Impatiens 'Sonic Red' and 'Sonic White' cuttings harvested from stock plants treated with higher ethephon doses resulted in greater ethylene concentrations during storage. Cuttings harvested 24 hours after treatment with 0, 250, 500 or 1000 mg• L-1 ethephon produced 0.07, 1.3, 1.7 or 5.8 mg •L-1 • g-1 (fresh weight) ethylene in the first 24 hours of storage at 20 °C, respectively. Cuttings harvested 24 hours after treatment with 500 mg• L-1 ethephon stored at 10, 15, 20, and 25°C for 24 hours produced 0.37, 0.81, 2.03 and 3.55 mg • L-1 • g-1 (fresh weight) ethylene. Ethephon treatment effects were measurable on harvested cuttings up to 3 weeks post application. Modified atmosphere storage of impatiens 'Sonic Red', geranium 'Kardino' and poinsettia 'Visions of Grandeur' cuttings showed that cuttings held in 1:20 oxygen:carbon dioxide generated higher ethylene concentrations than any other treatment including atmospheric control. Cuttings stored in ratios of 10:10, 10:5, 5:10, 5:5 oxygen to carbon dioxide generated less ethylene compared to atmospheric control. Cuttings stored in 10:5 performed best during propagation, with less leaf yellowing or abscission than any other treatment.