Abstract
The response of bermudagrass clones (Cynodon spp.) to reduced light intensity was determined in a greenhouse experiment. Thirty-two phenotypically diverse bermudagrass clones from broad geographic origins were subjected to two light treatments. The high-light treatment consisted of sunlight supplemented with fluorescent and incandescent light banks (160 µmol·s–1·m–2). The low-light treatment was a 90% reduction of the high-light treatment (16 µmol·s–1·m–2). Visual color, leaf length, stem internode length, stem elongation, chlorophyll concentration, and dry weight were measured. Bermudagrass clones responded to reduced light by exhibiting shorter leaves, shorter stem internodes, reduced green color, lower chlorophyll concentration and decreased dry weights. ‘Boise’, ‘No Mow’, ‘R9-P1’, ‘NM2-13’, and ‘NM3’ have been identified as being moderately insensitive to reduced light intensity, and data suggest enough variability exists to select for shade tolerance in bermudagrass.
Heavily shaded environments often limit the performance and persistence of hybrid bermudagrass (Cynodon dactylon × C. transvaalensis), therefore a field-based shade study was performed to determine whether different mowing heights (0.5 and 1.5 inch) or two trinexapac-ethyl (TE) growth regulator management treatments (control and 2 oz/acre) allow either ‘TifSport’ or ‘TifGrand’ hybrid bermudagrass to persist under 77% shade. Turfgrass quality (TQ), green cover, normalized difference vegetation index (NDVI), and dark-green color index (DGCI) were evaluated on the two cultivars under a shade structure in Tifton, GA, during 2010 and 2011. Neither of the cultivars maintained acceptable TQ throughout the entire year under 77% shade, although ‘TifGrand’ displayed adequate TQ at the higher mowing height (1.5 inch) and demonstrated more shade tolerance than ‘TifSport’, as indicated by TQ, green cover, and NDVI. The TE application did not enhance the turf performance of ‘TifSport’ under 77% shade when mowed at 0.5 inch, but it improved turf performance of ‘TifGrand’ at the same height. The effect of TE application was cultivar and mowing height dependent under this heavily shaded environment, which warrants future study to determine the best management practices of these cultivars as well as continued efforts to develop new, shade-tolerant bermudagrass hybrids.
turfgrass species grown under reduced light intensity environments ( Barrios et al., 1986 ; Beard, 1965 ; Jiang et al., 2004 ; McBee and Holt, 1966 ; Peacock and Dudeck, 1981 ; Tegg and Lane, 2004 ). Zoysiagrass has demonstrated good tolerance to
Abstract
Rapid in vitro propagation of Cordyline terminalis was achieved through the induction and proliferation of shoots of stem explants using a modified Murashige and Skoog medium supplemented with 0.5 ppm of 6-benzylamino purine (BA). No growth regulators were required for rapid rooting of shoots. Plantlets were successfully transplanted to vermiculite under a light mist and reduced light intensity.
Abstract
After 48 days rooting percentages and quality were highest for cuttings from Hibiscus rosa-sinensis plants grown under a reduced light intensity (65% natural light) regardless of (2-chloroethyl)phosphonic acid (ethephon) sprays at 100-5,000 ppm or indolebutyric acid (IBA) treatment to cuttings (0.8%). Ethephon and IBA treatments only affected cuttings from plants grown in 100% natural light, but rooting was not superior to that of cuttings from plants grown under reduced light. After 62 days, there were no treatment differences.
Abstract
Partial shading, as a means of preventing or decreasing flower development, was used to study the influence of flowering on leaf rootability. Reduced light intensity decreased the size of flowers and sugar levels in leaves. The rooting-potential of leaves from plants grown under 25 percent shade was reduced compared to full sunlight controls; but was increased in the ones from under 95 percent shade. Exogenous hormone application improved rooting of leaves from full sunlight and 25 percent shade treatments, but reduced rooting in those from 95 percent shade. It was suggested that the reduction or prevention of flowering improves rooting-potential because of less active competition for materials necessary in rooting.
Abstract
‘Paul Richter’ tulips were forced in controlled environment chambers at 26/22, 22/18, and 18/14°C day/night temperatures using high and reduced light intensity and short and long daylengths. Photoperiod had no influence on growth or flowering. Reduced light intensity with the coolest temperature treatment significantly increased the forcing period. Increased forcing temperatures had the greatest impact on plant growth, resulting in reduced Plant flower length, and forcing period. In a second experiment, ‘Paul Richter’ was forced in controlled environment chambers under 8 combinations of day/night temperatures from 18 to 26° day and from 14 to 22° night. The warmer day or night temperatures decreased the forcing period. Plant height was increased with increasing day temperatures, but decreased with increasing night temperature. Flower length decreased with increasing day or night temperatures. First internode length was increased with increasing day temperature but decreased with increasing night temperature, with the exception of a slight increase at a day temperature of 18°. Last internode length was increased only slightly with increasing night temperature. Flower longevity and total length were decreased slightly by increased forcing temperatures.
Schefflera arboricola was held in light- and temperature-controlled chambers for 6 months under three light intensities of 10 μmol·m–2·s–1, 20 μmol·m–2·s–1, and 80 μmol·m–2·s–1 measured as photon flux density (PFD). Plants also received three temperature regimes: 15 °C, 20 °C, and 25 °C. Reduced light intensity significantly decreased fresh and dry weight and increased chlorophyll content, but did not affect leaf thickness and palisade and spongy mesophyll parenchyma. High temperatures reduced fresh weight and significantly increased chlorophyll content and leaf thickness. The authors conclude that reduced photosynthetic energy flow at low light intensities (10 μmol·m–2·s–1, 20 μmol·m–2·s–1) could not be buffered by a downregulation of energy-consuming processes. Therefore the life span and quality of S. arboricola is reduced at such PFD values, especially at higher temperatures. Plants lose their marketability within 6 months.
Abstract
Rapid in vitro propagation of Anigozanthos manglesii D. Don. was achieved through the initiation and proliferation of shoots from lateral bud explants using a modified Murashige and Skoog medium, or Gamborg, Miller and Ojima B5 medium, supplemented with 0.5 ppm benzylaminopurine (BA) and 0.5 ppm naphthaleneacetic acid (NAA). Continued proliferation was obtained by sub-culture either on the same media or media containing 0.25 ppm BA plus 0.25 ppm NAA. Rapid rooting of shoots occured following transfer to a half strength B5 medium containing 0.2 ppm NAA. Plantlets were successfully transplanted onto a University of California (UC) potting mix under mist and reduced light intensity. The method has also been successfully employed with Anigozanthos flavidus Redoute and with Macropidia fulginosa (Hook.) Druce.
The cultivation of ornamental plants under different types of shelter and covering materials which reduce light intensity, resulting in morphological and physiological changes, needs to be evaluated before any large-scale use of such types of shelter covers. Baby rubber plants were grown in pots filled with peat under four different shelters and covering materials as follows: MG (multitunnel greenhouse with thermo-reflective aluminised screen), BG (buried solar greenhouse with thermo-reflective aluminised screen), NH (net house covered only with antipest mesh) and NH-AS (net house with antipest mesh and thermo-reflective aluminised screen). At the end of the experiment, the growth parameters and color of leaves, as well as photosynthetic and nutritional parameters, were assessed for each treatment. Baby rubber plants grown under NH-AS showed the highest values for growth parameters. The absence of shading in a net house may result in photoinhibition, reducing the growth and increasing the values of red (R) and blue (B) in leaves, which may be related to the increase of anthocyanin synthesis. The low level of radiation intercepted in the multitunnel and the buried greenhouse increased chlorophyll, N and P leaf concentration, while for K concentration, there was no clear trend and Na and Cl leaf concentration were similar under the different types of shelter. We concluded that the production of baby rubber plants under net house with antipest mesh and thermo-reflective aluminised screen is the best option to maximise the market value of baby rubber plants.