Floriculture and Ornamentals
Marketable size plants of sweet viburnum (Viburnum odoratissimum Ker-Gawl.), waxleaf ligustrum (Ligustrum japonicum Thunb.), and azalea (Rhododendron spp. L. `Southern Charm') grown in 11.4-L containers were irrigated with overhead impact sprinklers at container spacings ranging from 0 to 51 cm apart. Water reaching the substrate surface was quantified and the percentage of that applied calculated as percent capture (% capture). Percent capture is defined as the percentage of water falling above the plant within a projected vertical cylinder of a container that reaches the substrate surface. For all species, % capture increased linearly with the decline in adjacent canopy interaction, which results from canopies extending beyond the diameter of a container. Increases in total leaf area or leaf area outside the cylinder of a container, in conjunction with increasing distance between containers, were significantly (P < 0.05) correlated with increases in % capture for ligustrum and viburnum. Increases in % capture partially compensated for decreases in percentage of production area occupied by viburnum containers as distances between containers increased, but not for the other two species. Under commercial conditions, optimal irrigation efficiency would be achieved when plants are grown at the minimum spacing required for commercial quality. This spacing should not extend beyond the point where canopies become isolated.
Plants infected with Meloidogyne spp. (root-knot nematodes) often are stunted and lose aesthetic value due to chlorosis, wilting, and leaf margin necrosis. We assessed reproduction of three root-knot nematode species, Meloidogyne arenaria, M. incognita, and M. javanica, on five plant taxa native to the southeastern U.S. The plant taxa included were: Hydrangea quercifolia `Oakleaf', Viburnum obovatum `Densa', Itea virginica `Little Henry', Illicium parviflorum, and Clethra alnifolia `Ruby Spice'. Three commonly grown non-native shrubs, Ligustrum japonicum `Texanum', Ilexcrenata `Compacta', and Buxus microphylla `Wintergem', also were included in the study to serve as susceptible, positive controls. Highest gall rating (10) was observed on roots of I. crenata `Compacta' infected with M. incognita, but highest number of eggs (6397 eggs/g of roots) was observed in plants of this cultivar inoculated with M. javanica. Few or no galls were observed on roots of the five native plant taxa, and nematode eggs were recovered only from roots of I. virginica `Little Henry' inoculated with M. arenaria and M. javanica (13 and 20 eggs/g of roots, respectively). Fresh weights of shoots or roots were not affected by nematode inoculation. Due to lack of root gall development and little or no reproduction on the native taxa, we conclude that these are resistant or immune to the three species of Meloidogyne and might be suitable for planting in infested soil.
99 ORAL SESSION (Abstr. 558-565) WOODY PLANT STRESS PHYSIOLOGY
99 ORAL SESSION (Abstr. 558-565) WOODY PLANT STRESS PHYSIOLOGY
Abstract
When compared at a level of 1 ft-c for 16 hours at a night temperature of 20°C, light from 5 types of sources delayed flowering of short-day plants (Chrysanthemum, marigold, Rieger begonia), promoted vegetative growth of 2 species of Ulmus, 2 each of Acer, and 1 of Koelreuteria, Rhododendron, Rhus, and Zelkova, and promoted flowering of long-day plants (carnation, marguerite daisy, Petunia) in the order from most to least effective: incandescent (INC) > high-pressure sodium (HPS) > > metal halide (MH) = cool white fluorescent (F) > > clear mercury (Hg). Poinsettia, Betula, Catalpa, Platanus, and Tilia continued to grow vegetatively in response to all sources. Ilex and 2 species of Pinus did not respond. Foot candles of light from HPS lamps had to be increased at least 4- to 8-fold to regulate vegetative growth of long-day plants and delay flowering of short-day plants in comparison to INC lamps. High-pressure sodium lamps were ineffective in promoting early flowering of long-day plants, regardless of intensity or duration.
68 WORKSHOP 9 (Abstr. 662–666) Ornamental Plant Breeding in the Midwest
Poster Session 7—Ornamental Plant Breeding 18 July 2005, 1:15–2:00 p.m. Poster Hall–Ballroom E/F
Poster Session 7—Ornamental Plant Breeding 18 July 2005, 1:15–2:00 p.m. Poster Hall–Ballroom E/F