66 ORAL SESSION 15 (Abstr. 478–484) Plant Growth Regulators/Marketing–Floriculture/Foliage
Paul A. Thomas and Joyce G. Latimer
Allen D. Owings
A greenhouse study was conducted to determine the influence of media containing varying volumetric proportions of composted cotton gin trash and pine bark on the growth of Coleus × hybridus 'Golden Bedder'. All media treatments were amended with 1.5 lbs/yd3 Micromax and 8 lbs/yd3 dolomite. Plant height, shoot dry weight, and visual quality ratings were determined six weeks after potting. Media composed of 100% cotton gin trash produced plants with significantly less height and shoot dry weight. Height inhibition was apparent by 3 weeks after potting. Coleus grown in media composed of 60-1002 pine bark had higher visual quality ratings than those grown in media having cotton gin trash as the primary constituent.
M. P. Kaczperski and A. M. Armitage
The effects of differing storage conditions prior to transplanting were examined for Salvia splendens `Red Hot Sally', Impatiens wallerana `Super Elfin White', Viola × wittrockiana `Universal Beaconsfield' and Petunia × hybrida `Supercascade Lilac'. Plug-grown seedlings were stored for 0, 1, 2 or 3 weeks at 5C or 10C and irradiance levels from incandescent bulbs at 0, 2 or 12 μmol s-1 m-2. A second group of plants were stored at 18C and irradiance from fluorescent bulbs at 105 μmol s-1 m-2 for the same time period. Temperature was more important than irradiance in maintaining plant quality over the storage period. Impatiens and salvia could be stored successfully for a minimum of 2 weeks at 5 or 10C with no appreciable loss of quality, petunia and pansy up to 3 weeks. Seedlings of all species showed diminished quality when stored longer than 1 week at 18C. After storage, petunias stored at 18C flowered sooner than those stored at 5 or 10C. However, these plants were single stemmed, with long internodes and few flowers while those plants stored at 5 or 10C developed multiple branching and a short, compact growth habit at flowering.
Krishna S. Nemali and Marc W. van Iersel
Optimal substrate volumetric water content (θ) and drought tolerance of impatiens, petunia, salvia, and vinca were investigated by growing plants under four constant levels of θ (0.09, 0.15, 0.22, and 0.32 m3·m-3). Gas exchange, quantum efficiency (ΦPSII), electron transport rate (ETR), non-photochemical quenching (NPQ), and leaf water potential (ϒ) were measured for all species, and response of photosynthesis (Pn) to internal CO2 concentration (Ci) was studied in petunia and salvia. Leaf photosynthesis (Pmax) was highest at a θ of 0.22 m3·m-3 for all species and did not differ between a θ of 0.15 and 0.22 m3·m-3 for vinca and petunia. The Pn-Ci response curves for petunia were almost identical at a θ of 0.22 and 0.15 m3·m-3. Regardless of species, ETR and ΦPSII were highest and NPQ was lowest at a θ of 0.22 m3·m-3. Based on these results, a θ of 0.22 m3·m-3 for salvia and impatiens and a slightly lower θ of 0.15 m3·m-3 for vinca and petunia, is optimal. Mean osmotic potential in all treatments was lower in vinca and salvia and resulted in higher turgor potential in these species than other species. Analysis of Pn-Ci response curves indicated that Pn at a θ of 0.09 m3·m-3 was limited by both gas phase (stomatal and boundary layer) and non-gas phase (mesophyll) resistance to CO2 transfer in salvia. At the lowest θ level, Pn in petunia was only limited by gas phase resistance, indicating that absence of mesophyll resistance during drought may play a role in the drought tolerance of petunia.
Kimberly A. Klock-Moore
Horticultural Compost Technology class at the University of Florida for making the GHC compost, and Lovell Farms, Miami, for the plant material and the used greenhouse growing substrate. This work was supported in part by a grant from the Center for Biomass
James E. Barrett and Terril A. Nell
Florida Agr. Expt. Sta. J. Ser., no. R-01440. The authors express appreciation for the technical assistance of Carolyn Bartuska and the donation of plant material by Natural Beauty of Florida. The cost of publishing this paper was defrayed
Michael A. Schnelle, B. Dean McCraw, and Timothy J. Schmoll
Blakely, Creekside Plants, Oologah, Okla., for their ingenuity and contribution of time, labor, and greenhouse space.
M.P. Kaczperski and A.M. Armitage
We thank Ball Seed Co. for supplying plant material for this project. The cost of publishing this paper was defrayed in part by the payment of page charges. Under postal regulations, this paper therefore must be hereby marked advertisement
W. J. Carpenter and G. R. Beck
Continuous lighting with Lucalox lamps at 58W/m2 supplementing natural daylight for 1 to 4 weeks after transplanting increased plant height, root length and fresh weight of Petunia hybrida Hort cultivar White Cascade, Tagetes erectra L. cultivar Moonshot, and Zinnia elegan cultivar Peter Pan Pink. Differences became larger between lighted and unlighted treatments as the lighting period increased. Plants lighted for 4 weeks after transplanting flowered earlier (9 to 23 days), were slightly shorter, and had larger top fresh weight than those unlighted, Impatiens sultanii cultivar Scarlet Elfin responded less than the other species.
James P. Gilreath
Postemergence applications of fluazifop-butyl and sethoxydim at rates of 0.28, 0.56, and 0.84 kg a.i./ha provided excellent control of seedling Digitarla ciliaris (Retz.) Koel and Eleusine indica (L.) Gaertn. in achimenes (Achimenes grandiflora Dc. ‘Cascade Violet Night’), impatiens (Impatiens wallerana Hook. f. ‘Elfin Salmon’), marigold (Tagetes erecta L. ‘Yellow Galore’), petunia (Petunia hybrida Hort. Vilm.-Andr. ‘Burgundy’), and salvia (Salvia splendens F. Sellow ex Roem. & Schult. ‘Blaze of Fire’). Herbicide treatment did not affect achimenes rhizome size or weight nor plant vigor, height, or bloom production of impatiens, marigolds, petunias, or salvia. Chemical names used: (±)–2[4–[[5–(trifluoromethyl)2–pyridinyl]oxy]phenoxy]propanoic acid (fluazifop-butyl); 2-(ethoxyimino)butyl]propyl]-3-hydroxy-2-cyclohexenl-1-one (sethoxydim).