Browsing by Author "Dr. Brian E. Whipker, Committee Member"

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    Effects of Preharvest Conditions and Postharvest Handling on Postharvest Characteristics of Cut Lilies, Roses, Sunflowers, and Zinnias
    (2009-04-28) Possiel, Erin York; Dr. Sylvia M. Blankenship, Committee Member; Dr. Brian E. Whipker, Committee Member; Dr. John M. Dole, Committee Chair
    Studies were conducted to determine the effects of preharvest humidity and water stress levels during production on cut Lilium L. and Helianthus L. stems and various postharvest procedures on cut Rosa hybrida L., Helianthus L., and Zinnia Jacq. stems. Subjecting Lilium ‘Dazzle’ and ‘Vermeer’ stems to high humidity during production did not reduce cut flower vase life but increased stem length and production time. In Helianthus, vase life, water uptake, stem length, stem diameter, and head diameter of cut ‘Sunbright’ stems were positively correlated with production time in high humidity. Applying water stress to ‘Dazzle’, ‘Vermeer’, and ‘Sunbright’ during production did not affect vase life at the treatment level; however, water potential readings during the last five days before harvest were negatively correlated with vase life in ‘Vermeer’, and water potential readings from up to 36 days before harvest were positively correlated with vase life in ‘Sunbright’. Bud number in ‘Vermeer’ was positively correlated with stem diameter, and stem diameter in ‘Dazzle’ and ‘Vermeer’ was reduced as soil moisture deficit increased. Quality of cut ‘Sunbright’ stems was reduced as soil moisture deficit increased. Vase life in cut ‘Vermeer’ and ‘Sunbright’ stems was negatively correlated with the change in fresh weight in both humidity and water stress preharvest experiments. Postharvest studies determined that R. hybrida vase life was influenced by cultivar and vase solution, where commercial preservative solutions resulted in longer vase lives and smaller changes in fresh weight than the controls, but also less water uptake. Exogenous ethylene did not affect vase life but decreased water uptake. Application of the anti-ethylene agent silver thiosulfate (STS) significantly improved vase life in a majority of the rose cultivars tested, but 1-methylcycloprepene (1-MCP) did not improve vase life over the control. Both vase life and water uptake were reduced when more than one stem was placed in a vase, where placing ten stems in a vase decreased vase life by 1.4 days and water uptake by up to 10.6 mL/stem/day. Leaving stems dry before placing in vases reduced vase life, but recutting immediately before placing in vases minimized the decline. Rose stems responded positively to increasing the amount of stem removed, where cutting from 1 to 15 cm off the end improved vase life. Drying stems of Helianthus ‘Sunbright’ for up to 48 hours did not significantly reduce vase life when stems were recut after drying time; however, vase life was affected by storage temperature such that the longest vase life of 13.2 days occurred when stems were stored for 3 days at 5°C. Placing more sunflower stems in a vase did not statistically affect vase life. Vase life of cut Zinnia ‘Benary Giant Deep Red’ stems was reduced when stems were recut compared to stems that were not recut. However, if stems were recut, a period of desiccation before placing in vases improved vase life. Vase life was improved by 2.1 days with the use of Floralife Professional as a pulse solution versus tap water and by 2.2 days when stems were stored in a bleach solution versus tap water. Storage temperature affected vase life with 5 hours of storage at 5°C followed by 2 days of storage at 1°C resulting in the highest vase life of 13.0 days. Short vase lives occurred as storage temperature increased, with a low of 6.5 days with 2 days of storage at 20°C. Varying the number of stems per vase did not significantly affect vase life.
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    Impact of 11 Elemental Nutrient Deficiencies on Shoot and Root Growth, and Foliar Analysis Standards of 13 Ornamental Taxa with Emphasis on Ca and B Control of Root Apical Meristem Development
    (2003-09-19) Pitchay, Dharmalingam S; Dr. Paul V. Nelson, Committee Chair; Dr. Udo Blum, Committee Member; Dr. Brian E. Whipker, Committee Member; Dr. Nancy G. Creamer, Committee Member
    Tissue analysis standards and complete visual deficiency symptoms of N, P, K, Ca, Mg, S, Fe, Mn, Cu, Zn, and B are crucial for monitoring plant nutrient status. Limited information is available on visual disorder symptoms and foliar analysis standards for vinca, celosia, marigold, zinnia, salvia, pansy, impatiens, begonia, petunia, ornamental cabbage, snapdragon and New Guinea impatiens. Synoptic visual deficiency symptoms were as follows: N - Symptoms began on lower leaves as uniform light green chlorosis to yellow and finally necrotic. Development of red to purple pigmentation was observed in marigold, snapdragon, begonia and ornamental cabbage. P - All foliage became deeper green, then lower leaves became purplish/reddish in some species, and finally necrotic. K - In the early stage of deficiency, plants became compact and deeper green. Later, necrosis developed on tips and margins of older leaves. Ca - Necrotic symptoms first developed on roots, then on young leaves and shoot apex. However, the shoot apices of New Guinea impatiens and impatiens did not develop necrosis. Mg - Interveinal chlorosis developed on older leaves followed by necrosis along the margins. S - The entire leaves became uniformly lighter green. Then the margins of all leaves became more chlorotic then the remainder of the leaves. Eventually, the margins developed necrosis. Fe - Young leaves developed interveinal chlorosis, generally from the base. Then the entire lamina turned chlorotic. The chlorosis then gave way to bleached whitish-yellow. Mn - Young and recently matured leaves developed chlorosis, and mature leaves developed stippling of necrosis. Drastic reduction of shoot and root growth was common. Flowering was severely inhibited. Cu - Impaired flower development includes reduced size and premature abscission. Desiccation and sudden death of tissue occurred on recently mature leaves. Chlorosis was generally not a distinguishing feature. Zn - Young and recently matured leaves developed puckering, chlorosis, and necrosis. Some plants developed purple pigmentation. B - Foliage became darker green and glossy. Young and recently matured leaves became thick, leathery and brittle with severe distortions. The roots were short and stubby. The rate at which symptoms occurred is an indication of the species sensitivity to a particular nutrient deficiency. The nutrient deficiency symptoms that were first to occur by species were as follows: begonia - N and Fe, celosia - N and K, impatiens - Ca, marigold - N and Fe, New Guinea impatiens 'Grenada' - Ca, New Guinea impatiens 'Timor' - Fe, ornamental cabbage - Ca and Fe, pansy - Fe, petunia - Fe, salvia - N, snapdragon - Ca, vinca - Fe, and zinnia - Ca. Root and shoot apical meristems are specialized areas where cell proliferation and organogenesis take place. The absence of Ca, B and CaB greatly reduced primary root growth relative to control within 12 hours. The number of abnormal nuclei decreased in the order of Ca > CaB > B deficient treatments. Nuclei in both Ca and CaB deficiency treatments showed a significant decrease in volume. Boron deficiencies initially resulted in an increased mitotic index (MI), concurrent with root apical meristem (RAM) distortion. Most of the increase in root diameter could be explained by an increase in the number of cell files in the cortex. Ca and B deficiencies together reduced both the MI and root tip distortion. Lack of B arrests cell death, and lack of Ca arrests cell division. The absence of B triggered cell division in the peripheral lateral root cap. This indicates that B may help to mitigate Ca deprivation effects in Ca deficient environment.