Terril A. Nell

Effects of exogenous sucrose on carbohydrate levels, flower respiration and longevity of potted miniature rose (Rosa hybrida) flowers during postproduction

Abstract The effect of continuous injection of exogenous sucrose on single flower postproduction longevity of attached flowers of potted ‘Meijikatar’ miniature roses was studied. At bud showing color, with sepals starting to unfold, plants were moved to interior conditions and started being continuously injected with a solution of 3% sucrose or distilled water. Carbohydrate levels, flower respiration and single flower longevity were assessed. There was some variability in the amounts of solution supplied to the plants. Infusion of exogenous sucrose increased attached miniature rose flower longevity by 1.5 days and also increased flower respiration rates. The higher the uptake rate of sucrose solution the longer the flowers lasted. Exogenously supplied sucrose was consumed by increased respiration and consequently, at day 6 after anthesis, no differences were found in nonstructural carbohydrate levels between water and sucrose treatments. However, percent of soluble sugars in the stem was higher in the sucrose-infused plants, suggesting that exogenous sucrose supply not only served as an extra source of respirable carbohydrates but also released stored carbohydrates to flower respiration. At flower death, leaf soluble sugars and total non-structural carbohydrates were higher in the sucrose infusion treatment and, independently of infusion treatment, flower soluble sugars and total non-structural carbohydrates positively correlated with flower longevity.

Investigation of proteins in petals of potted chrysanthemum as a potential indicator of longevity

Abstract The SDS-PAGE protein profiles of four potted chrysanthemum cultivars (Dendrantrema grandiflora Tzvelev.) with flower longevities of 17–25 days were determined from flowering to senescence. The chrysanthemum flower is non-climacteric and therefore ethylene does not appear to play a role in flower senescence, during which only minor changes in both the protein content and the proportion of the major polypeptides were observed. This apparent stability of the proteins may contribute to the long post-harvest life of chrysanthemum flowers. Of the major polypeptides only a few increased in proportion from flowering to senescence. A 40 kDa polypeptide increased from flowering to senescence in two short-lived cultivars ‘Yellow Tara’ and ‘Orinda’ and in the long-lived cultivar ‘Dana’. Polypeptides at 45 and 65 kDa increased in two long-lived cultivars ‘Eureka’ and ‘Dana’, and the 65 kDa polypeptide also increased in the short-lived ‘Orinda’ cultivar. The increase in these polypeptides during flower senescence is of particular interest because they may be linked to flower longevity.

Horticultural Performance of Ethylene Insensitive Petunias

To determine the potential for use of biotechnology to produce ethylene insensitive floriculture crops, we designed several experiments to measure horticultural performance of transgenic CaMV35S-etr1-1 petunias. Delayed floral senescence is observed at varying degrees in transgenic plants depending on production environment. Flowers grown in cooler greenhouse environments show greater delays in pollination-induced and natural flower senescence than those grown in warmer environments. Fruit set of self pollinated CaMV35S-etr1-plants was reduced compared to wild type plants, and was also dependent on production environment. Transgenic plants grown in warmer environments showed reduced fruit set after self pollination compared to those grown in cooler environments. Fruit ripening is delayed, and adventitious root formation is significantly reduced in transgenic CaMV35S-etr1 plants compared to wild type plants. These observations lead us to suggest that tissue specific ethylene insensitivity will be required to produce ethylene insensitive floriculture crops with extended flower life.

Effect of nitrogen and sulfur applications on pot chrysanthemum production and postharvest performance. II. Plant growth responses

Chrysanthemums are one of the most important flowering plants produced internationally year round. The objectives of this research were to evaluate the effects of reducing nitrogen (N) applications by adding sulfur (S) and to determine if N * S interactions occur during the production and postharvest longevity of pot chrysanthemums. Pot chrysanthemum ‘White Diamond’ was grown in a peat-based medium following a typical production schedule except for fertilization. Plants received N at 50, 100, 150, or 200 mg L−1 in combination with S at 0, 5, 10, 20, or 80 mg L−1. Variables evaluated were leaf N and S concentrations, plant height, leaf area, days to bud set, and first flower color and inflorescence anthesis as well as size and longevity under simulated interior conditions. N * S interactions were significant for significantfor all plant growth response variables. Applications of 50 mg N L−1 resulted inpoor leaf N and S concentration and plants of questionable quality, yet maximal postharvest longevity. Nitrogen applied at 100, 150, or 200 mg L−1 in combination with at least 10 mg L−1 S had acceptable leaf N and S concentrations and produced plants of commercial quality with adequate postharvest longevity. Thus, N applied at 100 mg L−1 was the minimum acceptable fertilizer rate. Thus, N applications can be reduced by half when S is applied during commercial production without compromising postharvest longevity.

Effects of pre- and post-harvest anti-transpirant applications on vase life of leatherleaf fern

Abstract Post-harvest water use of leatherleaf fern ( Rumohra adiantiformis [G. Forst] Ching) was not affected when Cloud Cover, Vapor Gard or Wilt Pruf 1 were applied 3–28 days prior to harvest. However, post-harvest anti-transpirant dips reduced water use during the first 24 h. The shortest vase life occurred in fronds dipped in water. The incidence of frond curl was not influenced by anti-transpirant applications.