containing 0.2% dimethyl sulfoxide and one-fourth-strength Murashige and Skoog basal salts. Table 1. Effect of colchicine concentrations on seedling survival and tetraploid induction in japanese privet ( Ligustrum japonicum ). Nuclear DNA contents. Sharp
Mohammed I. Fetouh, Abdul Kareem, Gary W. Knox, Sandra B. Wilson and Zhanao Deng
Dilma Daniela Silva, Michael E. Kane and Richard C. Beeson Jr.
-to-shoot ratio is also modified by natural growth patterns. Many woody species, such as Ligustrum japonicum Thunb., exhibit an episodic growth habit, fluctuating between periods of rapid shoot growth and slow root growth and periods with the inverse pattern
Jeff S. Kuehny and Mary C. Halbrooks
Research defining actual changes in weight gain of roots and shoots during growth episodes of woody ornamentals is limited. The objective of this study was to develop a better understanding of the patterns of root and shoot growth, nitrogen uptake, and changes in carbohydrate and protein content of Ligustrum japonicum, an episodic species. Shoot elongation and lateral root formation were synchronous. The greatest increase in shoot percent of whole plant fresh weight occurred after shoot elongation however, and the greatest increase in root percent of whole plant fresh weight occurred during shoot elongation. Nitrate uptake was highest during shoot elongation and lateral root formation. Carbohydrate and protein content also varied with each episode of growth.
J.L. Heilman and J.M. Ham
The heat balance method of measuring mass flow of sap was tested on wax leaf ligustrum (Ligustrum japonicum Thunb.) to evaluate its usefulness for measuring water use in shrubs. Sap flow measurements were compared with gravimetric estimates of transpiration in growth chamber and field environments. Sap flow measurements in both environments were within 10% of transpiration, which compared favorably with results reported for herbaceous plants by other researchers. Sizable differences in sap flow, due mainly to differences in leaf area, were found among five plants tested in the field. When flow was expressed on a unit leaf-area basis, differences among plants were greatly reduced. Measurements under partly cloudy skies with fluctuating irradiance showed that changes in sap flow matched those occurring in irradiance.
In Florida, ornamental nurseries and other agricultural entities have been required to obtain volume-limited permits for irrigation water since 1992. Since then, volumes permitted for nurseries have declined. This project set out to establish maximum annual irrigation quantities for Ligustrum japonicum Thumb. grown in three common container sizes. Plants were scheduled and grown such that every 4 months, beginning 1 Jan., plants 2 months from marketable size would be available to place in suspension lysimeters with accompanying border plants. Once in lysimeters, plant weights were recorded every half-hour for 4 months. At that point, plants were 2 months larger than marketable size, thus averaging marketable size over the 4-month period. Data were collected through six 4-month cycles (2 years), along with daily calculation of reference evapotranspiration and monthly canopy measurements. Irrigation was applied overhead and based on a minimum 30% reduction in plant available water within a container. Daily actual evapotranspiration was used to calculate a water need index for each plant. These water need indices, normalized by different surface areas, will be discussed, along with comparisons of cumulative actual evapotranspiration to irrigation depth applied.
Jeff S. Kuehny, William B. Miller and Dennis R. Decoteau
Rooted cuttings of Ligustrum japonicum Thunb., an episodically growing species, were grown hydroponically in a controlled-environment growth chamber to determine allocation of glucose, mannitol, total soluble sugars, and total protein in mature leaves, flush leaves, stems, and roots. During the 65 days of episodic growth, 43% of the total soluble sugars was glucose and 33% mannitol. Glucose concentrations of mature leaves decreased during the first root growth episode, increased in almost all plant tissue during a shoot growth episode and decreased in all plant tissue at initiation of a second root growth episode. Mannitol concentrations in the roots and stems decreased during episodes of root growth and increased during a shoot growth episode when leaf flush mannitol concentrations increased. Radiolabeled C applied to leaves before the initiation of the first period of shoot elongation was translocated to the roots. After shoot elongation, just before a root growth episode, most labeled C was translocated to new shoots and roots. Autoradiographs indicated that subsequent episodes of shoot growth were supported by photosynthate from the previous shoot flush. Protein concentrations decreased in all plant tissues during shoot growth but increased in roots and mature leaves during root growth. Concentrations of 15N in leaf and stem tissue indicated retranslocated N supported each episode of shoot growth. Changes in endogenous C and N concentrations and allocation patterns in ligustrum were linked to the control of episodic shoot and root growth.
Dilma Daniela Silva, Richard C. Beeson Jr. and Michael E. Kane
138 DAT (7 July 2009). Fig. 1. Shoot tips of Ligustrum japonicum at different growth stages: ( A ) tip with no unfolding of leaves, ( B ) new bud, ( C ) new bud expansion, and ( D ) growing shoot tip. Results and Discussion Growth under short wet
Shawn T. Steed, Allison Bechtloff, Andrew Koeser and Tom Yeager
Mulches have many positive benefits for the production of plants, ranging from weed suppression to water conservation. In this study, a novel method of using plastic film mulch for container-grown plants was evaluated. Plots of 25 japanese privet (Ligustrum japonicum) in #1 (2.5 qt) nonspaced containers were wrapped with 1.25-mil white or black plastic mulch over the top and sides of containers. Small plants were planted through the plastic and grown for 22 weeks with overhead irrigation. Water application amount was determined by moisture sensors placed in the substrate of each treatment. Plant growth, dry weights (DWs), weed fresh weights, weeding time, substrate electrical conductivity (EC), substrate temperature, total water applied, and mulch costs were determined. Black plastic (BP) and white plastic (WP) mulch reduced water applied by 82% and 91%, respectively, compared with the nontreated control (NT). Nontreated control plants grew faster and had greater DW at the end of the experiment. Mulched containers had fewer weeds and required less labor to remove weeds than the NT treatment. Substrate EC level was greater in BP and WP treatments than for the NT after 20 weeks, and plastic mulch did not result in different substrate temperatures. Plastic mulch added $4.94/1000 containers ($2.24 input cost and $2.70 removal cost) to production costs, not including disposal costs. This novel method of mulching nonspaced plants reduced irrigation water, herbicide applications, and weeding labor, but probably added 2–3 weeks to finish time.
Tim R. Pannkuk
Landscape water conservation methods and techniques contribute to managing water resources. Use of reference evapotranspiration (ETo) data and landscape coefficients is one method that needs further development. Local ETo data and actual plant water use were used to calculate plant factors (PFs) for three model landscapes composed of mixtures of turfgrass and shrubs. Model landscapes using a sandy loam soil included st. augustinegrass (Stenotaphrum secundatum), privet (Ligustrum japonicum), dwarf burford holly (Ilex cornuta ‘Burfordii Nana’), and dwarf yaupon holly (Ilex vomitoria ‘Nana’) at three ratios of turfgrass to shrub vegetative cover: 80:20, 50:50, and 20:80. Soil was placed into inground lysimeters in a complete randomized block design with soil moisture sensors and a drainage system. Lysimeters were irrigated with a sprinkler system, and water was applied at a rate of 100% replacement of ETo minus precipitation. Lysimeter soil leachate was collected from the drainage system and quantified. After 2 years, the PF of 20:80 and 50:50 turfgrass/shrub combination were greater than the PF of the 80:20 combination. Plant factors for the 80:20, 50:50, and 20:80 turfgrass:shrub combinations were 0.68, 0.97, and 1.01, respectively. There were no seasonal differences in PFs. Total growing season leachate depth over 2 years was 63.4, 30.7, and 12.6 mm for 80:20, 50:50, and 20:80, respectively. Further work on PFs should include other plant combinations, and evaluation in other climatic zones.
Dilma Daniela Silva and Richard C. Beeson Jr.
). To facilitate observation, the rhizotron was supported by four legs (60 cm) at the tip of each arm. Fig. 1. Prototype rhizotron with Ligustrum japonicum 2 months after transplanting into rhizotron. Doors of rhizotron open only for demonstration. ( A