Poinsettias and other floral crops when treated with the growth retardant uniconazole, Sumagic™, are more compact in growth habit. They have also been shown to have reduced stem strength. Calcium applied as a drench has been demonstrated to increase plant height and plant dry weight of poinsettias. Unicomazole reduced plant height without affecting dry weight. Bract color was more intense when calcium was applied as a weekly spray. Poinsettia plants had greater levels of foliar calcium when applied as a drench. Poinsettia plants sprayed and drenched with calcium and treated with uniconazole had greater levels of foliar calcium, however, this was not significantly greater than the control plants treated with uniconazole alone. The lowest level of foliar calcium was observed in uniconazole treated plants where calcium was applied as a spray. Uniconazole applications weakened the stein structure of poinsettias as with other floral crop species.
D.K. Harris, A.D. Owings and S.E. Newman
J. Ray Frank
32 ORAL SESSION 1 (Abstr. 387–391) Crop Protection & Weed Control–Woody Ornamentals/Landscape/Turf
Scott J. Josiah, Heidi Brott and James R. Brandle
Producers in the central United States are showing considerable interest in growing alternative crops such as specialty forest products for food, herbal medicinal, decorative floral and craft markets. Crops showing particular promise are shrubs and trees that produce decorative woody stems such as curly willow (Salix matsudana), scarlet curls willow (S. matsudana `Scarlet Curls'), french `Scarlet Curls'), french pussy willow (S. caprea), red twig dogwood (Cornus sericea), and branches of flowering trees and shrubs, including apple (Malus spp.), cherry (spp.), cherry (Prunus spp.), and forsythia (Forsythia spp.). spp.). The objectives of this study were to 1) determine yields and performance of 10 woody plant cultivars used in the floral industry, and planted in an alley-cropping configuration, and 2) quantify wholesale prices, establishment and maintenance costs, management and harvest labor inputs, and financial returns by cultivar. Production and performance data are derived from a 40-acre (16.2-ha) alleycropping trial in Nebraska containing 10 species or cultivars of shrubs that produce woody florals. Results are based on two harvests that commenced two and three growing seasons after establishment. Harvested woody stem size and quality were measured and determined, and sold to wholesale florists to determine prices and identify buyer requirements. Annual gross financial returns ranged from a high of $24.94/plant for scarlet curls willow to a low of $0.63/plant for bloodtwig dogwood (C. sanguinea var. atrosanguinea), while net returns per plant for these species ranged from a positive $17.46 to a loss of $1.30. Financial returns varied among species and cultivars due to the combined effects of annual marketable stem production, harvesting and processing labor requirements, and price/stem. Stem production increased over time due to subsequent coppicing of harvested plants. Overall findings indicate that commercial production of selected cultivars of woody florals in an alleycropping arrangement can be a profitable alternative to using conventional woody species.
D. Scott NeSmith and Gerard Krewer
Johannes S. Verreynne and Carol J. Lovatt
Oral Session 17—Crop Physiology Moderator: Rebecca Darnell 19 July 2005, 2:00–4:00 p.m. Room 108
Adán Fimbres Fontes, Raúl Leonel Grijalva Contreras, Manuel de Jesus Valenzuela Ruiz and Gerardo Matínez Díaz
The region of Caborca is actually the largest grape-growing area in Mexico, with 14,000 ha. The main problem in this zone is the lack of water, and it is important to use this resource rationally. During 1990 and 1991, a drip irrigation experiment in `Thompson Seedless' table grapes was conducted. The four treatments were 120%, 166%, 206%, and 250% of the evaporation from a evaporation pan type A. The crop coefficients (Kc) applied were 7.5%, 15%, 52.5%, and 80% from the beginning of budding until 1 week after harvest, and 7.5% after harvest (postharvest). The results indicated that the best treatments were 120% (105 cm of total water applied) and 166%, with no reduction in the floral buds (5.4 per cane for 120); however, 206% and 250% (202 cm of total water applied) got the lowest number of floral buds (0.90 per cane) for the following year, and, because of that, the lowest clusters per cane.
Kelly M. Anon and Richard Craig
Interspecific hybrids of Exacum species (Gentianaceae) endemic to Sri Lanka possess excellent qualities for domestication as a new floriculture crop. The exact mode of floral induction and development responses are unknown, impeding the introduction of this potential crop. The interspecific hybrids evaluated are the result of controlled cross pollinations of E. macranthum. Arn. ex Griseb., E. trinervium (L.) Druce ssp. trinervium, and E. trinervium ssp. ritigalensis. (Willis) Cramer. The hybrids exhibit great genetic variability for horticultural traits. In addition, two growth and flowering patterns exist within the Penn State germplasm. Continuous-flowering genotypes flower throughout the year but more profusely and rapidly under late spring and summer conditions. In contrast, periodic-flowering genotypes exhibit two distinct seasonal habits. Under winter conditions, these accessions have a rosetted habit, much secondary branching, and few or no flowers. In summer conditions, they break their apical dominance, bolt, and produce flowers. As members of the Gentianaceae, Exacum hybrids produce an elegant blue flower with a striking yellow eye and bottle-shaped anthers. We evaluated the growth and flowering responses of Exacum interspecific hybrid accessions to photoperiod and irradiance. Accessions were evaluated under greenhouse conditions for floral production, rate of floral development, and growth characteristics. For the 20 accessions evaluated, supplemental irradiance under winter conditions resulted in greater floral production and much greater shoot and root mass accumulation. Little height and branching response occurred with supplemental irradiance. Of the 15 accessions evaluated under four photoperiod regimes, flowering and growth responses to photoperiod occurred under summer conditions but not in winter. An interaction among season, accession, and photoperiod revealed the complexity of Exacum germplasm and environmental responses.
Samuel Salazar-García, Luis E. Cossio-Vargas, Carol J. Lovatt, Isidro J.L. González-Durán and María H. Pérez-Barraza
Several studies were undertaken in commercial nonirrigated `Hass' avocado orchards under the subhumid semiwarm subtropical climate of the state of Nayarit, Mexico, with the following objectives: 1) to determine the frequency and intensity of vegetative shoot flushes and their contribution to the production of floral shoots, 2) to quantify the effect of tree fruit load on the occurrence of vegetative shoot flushes during the year and the relationship between vegetative and reproductive shoot number during flowering, and 3) to determine the time when apical buds borne on the major vegetative shoot flushes reached irreversible commitment to flowering (floral determination) through the use of shoot defoliation and girdling. Data trees were selected in two orchards based on their current crop load. Four to five branches per tree were tagged, and the number and intensity of vegetative flushes that developed during 2 years, as well as the type of growth produced by apical buds of shoots of different ages, were recorded at the end of the winter bloom periods for two separate years, 1999 and 2001. In a separate experiment using a different set of trees, winter and summer flush shoots were defoliated (year 1) or defoliated and girdled (year 2) at different stages of bud development from September to January in each case. Four vegetative flushes occurred each year. The winter flush that emerged in Feb. 1998 made the greatest contribution to the 1999 winter bloom—76.5% of the shoots produced floral shoots. Contributions of the summer 1 (late July 1998), summer 2 (early Aug. 1998), and summer 3 (late Aug. 1998) flushes to flowering were intermediate. A total of 30.6%, 36.4%, and 19% of the shoots produced floral shoots respectively. All four vegetative flushes produced a similar number of vegetative shoots during winter bloom. Evaluation of the 2001 winter bloom for trees with high (>95 kg fruit/tree) and low (<70 kg fruit/tree) crops showed no effect of tree fruit load on the production of vegetative or floral shoots by winter or summer vegetative flushes. Irrespective of time of treatment (shoot defoliation and girdling) or shoot age, irreversible commitment to flowering of apical buds occurred by 15 Oct., and this stage was associated with an average of 27.5 chilling days (temperature, ≤19 °C) for both years. Buds irreversibly committed to flowering were closed and pointed, with partial senescence of bud scales. Anatomically, the buds showed a convex primary axis meristem and four secondary axis floral shoot meristems.
D. Scott NeSmith and John R. Duval
Transplants for both vegetable and floral crops are produced in a number of various sized containers or cells. Varying container size alters the rooting volume of the plants, which can greatly affect plant growth. Container size is important to transplant producers as they seek to optimize production space. Transplant consumers are interested in container size as it relates to optimum post-transplant performance. The following is a comprehensive review of literature on container size, root restriction, and plant growth, along with suggestions for future research and concern.
R. Nunez-Elisea, M. L. Caldeira and T. L. Davenport
185 ORAL SESSION (Abstr. 723-730) FRUIT CROPS: GROWTH SUBSTANCES