185 ORAL SESSION (Abstr. 723-730) FRUIT CROPS: GROWTH SUBSTANCES
R. Nunez-Elisea, M. L. Caldeira and T. L. Davenport
William B. Miller and Shi Niu
Sucrose is the major form of translocated carbohydrate in most plants. While enzymes of sucrose degradation have been well studied in many agronomic crop sinks, little is known about the physiology of sucrose breakdown in most floral tissues. Invertase and sucrose synthase are accepted as the key enzymes responsible for sucrose breakdown. As the first step in studying sucrose breakdown in Lilium longiflorum, we characterized floral bud invertase enzymes. Three soluble invertases were present in developing buds, and were resolved by DEAE-Sephacel chromatography (Invertases I, II, and III, in order of elution). After further purification, each enzyme was characterized. Each was an acid invertase (pH optima of 4.0 to 5.0). each had Km values for sucrose of 5.0 to 7.0 mM. To determine if the enzymes had tissue-specific localization, anthers were dissected from tepal, pistil, and filament tissues. Invertase I was localized primarily in anthers, with invertases II and III being present in much smaller amounts. Invertases II and III were the major forms in the other floral tissues with essentially no invertase I detectable.
Brent Black, Mark Ehlenfeldt and Robert Martin
Precocious varieties of highbush blueberry may over-crop during the first few seasons in the fruiting field, adversely affecting plant establishment. Reducing or preventing bloom in the nursery and during establishment would be beneficial in preventing early cropping and reducing the risk of infection by pollen-borne viruses. We investigated the efficacy of foliar applications of ProVide® (Valent BioSciences), a commercial GA4+7 formulation, for suppressing flower bud initiation in blueberry. One-year-old rooted cuttings of `Bluecrop' were obtained from a commercial nursery and established in 11-L pots at the Blueberry and Cranberry Research Center, Chatsworth, N.J. Dilute foliar applications of ProVide® were made at concentrations ranging from 50 to 400 mg·L-1 a.i., ranging from 7 July to 1 Sept. 2004, with 10 replicate plants per treatment. Floral and vegetative buds were counted the following spring. A separate experiment was initiated in 2005, with concentrations of 200 and 400 mg·L-1 a.i. applied in August and September. For the 2004 study, the greatest flower bud suppression resulted from repeat applications at 400 mg·L-1 a.i. Weekly applications from 7 July to 1 Sept. resulted in a 70% reduction in flower bud number, whereas three weekly applications from 18 Aug. to 1 Sept. reduced flower bud number by >88%. Neither treatment significantly reduced total bud numbers (vegetative + floral) compared to untreated and water-sprayed controls, indicating that the treatments did not reduce plant growth. Results for the 2005 treatments will also be presented.
Paul D. Curtis, Elizabeth D. Rowland, Meena M. Harribal, Gwen B. Curtis, J. Alan Renwick, Mathew D. Martin-Rehrmann and George L. Good
voles, and, together with W. Miller, gave valuable comments on the manuscript. The project was funded by the U.S. Dept. of Agriculture, Agricultural Research Service, Floral and Nursery Crops Initiative, and the Cornell Agricultural Expt. Station, Hatch
Juan I. Valiente and L. Gene Albrigo
Citrus flowering is a complex phenological process influenced by a number of interacting factors. Low winter temperatures are recognized as an important factor, but the flowering response has not been quantified under Variable natural conditions. A study was conducted to monitor the flower bud induction response of `Valencia' and `Hamlin' sweet orange trees [Citrus sinensis (L.) Osbeck] to naturally occurring winter weather conditions during the 1999 and 2000 seasons. The flowering response was quantified and related to shoot age, bud position along the shoot, local weather information, and crop load status. Results indicate that buds on previous summer shoots developed 2.52 and 3.59 to 1 flower on spring shoots, for `Hamlin' and `Valencia', respectively. In addition, buds at apical positions produced more flowers than buds located far from the apex. These basal positions buds required higher induction levels. Under Florida conditions, greater accumulation of hours of temperatures 11 to 15 °C increased floral intensity by the combined effect on the number of sprouting buds with reproductive growth and the number of flowers per flowering bud. Some statistical analyses indicated that high winter temperatures reduced flowering in `Valencia' and `Hamlin' oranges. The presence of fruit consistently reduced reproductive response for both cultivars. Crop load reduced flowering by an average of 41.5% compared to no crop and varied by cultivar. A discussion on the different induction requirements as well as on the differential effect of crop load on flowering by cultivar is presented.
Christine Meyer, Ellen T. Paparozzi*, Scott J. Josiah and Erin M. Blankenship
Woody floral stems are an emerging specialty crop within the floral industry, and stem color is a key to marketability. This study was conducted to assess stem color change over time in order to determine the optimum window for stem harvest. Plants of `Scarlet curls', `Flame' willow, `Bailey', `Cardinal' and `Yellow twig' dogwood were planted in a randomized complete block design in rows parallel to a windbreak.. Each experimental unit consisted of a group of five plants, each of the same cultivar. Plants were initially tagged at a set height and stem diameter and measured for color. Each stem was also tagged with one of three colored tapes, according to initial color: green for green colored stems, red for stems already showing color change, and pink for intermediate colored stems. Color was assessed initially and on a weekly basis for 10 weeks, starting at the end of September, using the Royal Horticultural Society color chart. Data were analyzed using a repeated measures procedure. `Scarlet curls' and `Flame' stems, already displaying color, attained the darkest color value for their cultivar at an early stage and were at the point of harvest in early November, while stems that were initially green never attained a similar dark color value. `Yellow twig' dogwood stems already displaying color and those beginning to color attained the darkest color value in late November. `Cardinal' stems attained a darker color value more quickly than other dogwood stems. In most cases, stems of `Cardinal' dogwood could be harvested from early October until early December, while early November was the optimum time to harvest `Bailey' dogwood stems. Woody florals planted closest to the windbreak were more variable in color development and, in some cases, appeared to be more vigorous.
Sabine Green* and Geno Picchioni
Floriculture, among the fastest-growing agricultural segments in New Mexico, is creating job opportunities for graduates. Limited faculty resources restrict growth in floriculture academic programs, particularly for curricular modernization, extracurricular activities, and capacity building of the student:industry relationship. Federal funding has provided a Program Coordinator to lead our floriculture academic programs, responsible for raising technical quality of floriculture courses, recruitment and retention of undergraduates, and establishment of regional alliances with industry to exploit job opportunities. During the first year of the program (2003), deliverable products included course modules, fund raising protocols, and public school workshops. Results demonstrate an affinity for students of Hispanic origin to the program (over 40% of enrollments). Industry support included over a 2-fold increase in 2003 horticultural internship placements, financial aid, and donations of expendable materials. Floriculture student participation in intra-campus governance and off-campus community service projects also defrayed program costs and resulted in institutional gain. Over 80% of the 25 students enrolled in the beginning floral design and floral crops judging class agreed or agreed strongly that they had an obligation to engage in fund raising efforts to strengthen the floriculture academic program. Our intent is to build the floriculture teaching program into a template that can be replicated into the future through sustained institutional commitment. The program can serve as a model for other academic departments seeking diversification of horticulture academic programs and recruitment of a diverse student body, but struggling with limited human resources.
Resource partitioning and plant storage components are important factors that influence the productivity and profitability of geophyte species produced as floral crops. We determined that inoculation with arbuscular mycorrhizal fungi (AMF) can alter different plant characteristics affecting productivity and quality of bulb and cut flower production of several floral geophytes including Brodiaea laxa, Zephyranthes sp., Sparaxis tricolor, Freesia × hybrida, Zantedeschia sp., and Canna sp. Plant growth, flower production, bulb/corm/tuber (bulb) production and composition were measured for two growth cycles after inoculation with Glomus intraradices. In general, shoots and flowers on plants inoculated with AMF emerged earlier than shoots and flowers on non-inoculated plants for species that produced most of their leaf area prior to flower emergence. However for species that produced leaves throughout the growth cycle or large flowers early in the growth cycle, AMF inoculation delayed shoot emergence and flower emergence. Many species that exhibited an earlier flower emergence or produced more flowers in response to AMF inoculation also produced smaller daughter bulbs and more offsets than non-inoculated plants. Across all species, the concentrations and contents of several storage components (Zn, S, and N, amino acids, and carbohydrates) that influence bulb quality were increased by AMF inoculation. Changes in partitioning between bulb and flower production resulting from AMF inoculation altered important aspects of commercial geophyte production for flowers or bulbs. AMF-induced increases in mineral uptake and resource storage are also related to aspects of quality important in the production of vegetative propagates.
C.L. Palmer, R.W. Langhans, R.K. Horst and H.W. Israel
48 ORAL SESSION 14 (Abstr. 115–122) Crop Protection/Cross-commodity
Tim D. Davis, Wayne A. Mackay and Narendra Sankhla
Big Bend bluebonnet (Lupinus havardii Wats.) is native to a narrow geographic range in southwestern Texas and produces attractive blue inflorescences (racemes) that may be used as cut flowers. Several crops were produced in the greenhouse to determine postharvest-characteristics of the cut inflorescences. Without any postharvest conditioning treatments, the inflorescences held in water had an average vase life of about 7 days. During this period, an average of 13 flowers abscised per inflorescence. When preconditioned for 4 hours in 40 to 160 mg·liter−1 silver thiosulfate (STS), vase life increased to 10 to 12 days and fewer than three flowers abscised per inflorescence. A commercial floral preservative (Oasis) had no effect on flower abscission or vase life of STS-treated inflorescences. Flower abscission and vase life were the same whether STS-treated inflorescences were placed in floral foam moistened with water or in water alone. Storing STS-preconditioned inflorescences in water at 5C for 72 hours did not affect flower abscission or vase life compared to the unstored control. Dry postharvest storage at 5C for 72 hours caused noticeable wilting, but, on dehydration, these inflorescences still had a vase life of about 8 days. Postharvest characteristics of pink-and white-flowered breeding lines were the same as for the blue-flowered line. These results indicate that cut inflorescences of L. havardii have desirable postharvest qualities and can be stored for up to 72 hours without seriously limiting vase life.