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- Author or Editor: Richard A. Criley x
Heliconia rostrata is a herbaceous-musoid sympodial rhizomatous plant that grows as clump. After three leaves are produced, each shoot of the clump may bear an inflorescence if it is induced by short days (SD). However, the relationship between shoot density and flowering has not been quantified. To evaluate the effects of the inductive period, number of shoots, and leaf removal on flowering, rhizomes were planted in 120 pots (8 L). One-third of the pots were planted with two rhizomes, while the remainder was planted with one. One-half of the pots with one rhizome were allowed to develop all their shoots for three generations, while in the remaining pots only one shoot per generation was allowed to grow. In addition, one-half of the plants in all the treatments were subjected to selective leaf removal. The plants were grown under long days (LD) >13 h in a glasshouse until four leaves were produced. Inductive SD was supplied to all the plants from 5:00 pm to 8:00 am. After 8 weeks of SD, one-half of the plants were given LD, while the other half continued under SD (conSD) until flowering. The highest percentage of flowering shoots (39% to 35%) was observed in plants under conSD; plants under SD-LD were 10% to 9%. The second generation of shoots showed the highest flowering (74% conSD and 21% SD-LD), followed by the first (62% conSD and 18% SD-LD), and third (31% conSD and 0% SD-LD) generations. Non-flowering shoots of the first generation were aborted or dead. Shoots of the third were still vegetative, since they had few leaves to be induced. Fewer flowers occurred in clumps allowed to develop all their shoots. Intact plants from rhizomes with one shoot per generation flowered more than the partially defoliated ones under conSD.
A new name for an old plant is not necessarily welcome in the horticultural trades or in plant identification classes, but some name changes have been in existence long enough that textbooks and trade publications should have caught up with them. The objective of this poster is to call attention to some of these changes for horticultural plant identification courses. Traditional references such as Hortus Third (1976) and Exotica 8 (Graf, 1976) have been superseded by the second edition of The Plant Book (Mabberly, 1997) and The Index of Garden Plants (Griffiths, 1994), while some recent works (The Tropical Look, Riffle, 1998) have chosen to retain old names. The taxonomic research underlying a new book, Tropical Garden Flora (Staples and Herbst, in press), based on the second edition of In Gardens of Hawaii (Neal, 1965), has produced an abundance of name changes. This poster will illustrate and report genera and species name changes that have occurred for selected ornamentals in the Acanthaceae, Agavaceae, Araceae, Araliaceae, Arecaceae, Commelinaceae, and Moraceae families plus a few others.
Seasonal flowering behavior of Heliconia wagneriana Petersen was found to be caused by short daylengths (SD) using artificial short days (8 to 9 hours) and long days as daylength extension or night break lighting with incandescent lamps. The natural time for flower initiation was estimated to be mid- to late October (11 hours 40 minutes to 11 hours 20 minutes) in Hawaii, and 120 to 150 days were required from the onset of inductive SD to inflorescence emergence. The results may be used to manipulate flower availability for flower markets.
Abstract
A seasonal pattern of flowering was observed in field production records of Heliconia stricta Huber. ‘Dwarf Jamaican’. That this seasonality could be photoperiod-related was indicated in greater yields for plants grown under 8-hr daylengths for 6 weeks when compared to plants given natural daylengths (about 13.5 hr). Depending on the capacity of the plant to respond to photoperiod, 3 or 4 weeks of short daylength (SD) were sufficient durations for flower initiation. Leaf number affected the response, as only 4% of pseudostems with <3 leaves at the onset of SD yielded flowers, while 91% of pseudostems with ≥4 leaves at the onset of SD produced flowers. From the start of SD, about 13 weeks were required for development of the inflorescence to anthesis for pseudostems starting with ≥4 leaves.
MacroMixer, a microcomputer spreadsheet program, offers 15 commonly used nutrient sources for quick formulation of a macronutrient mix in solution culture. The program displays the total concentration of each macro-element and the contribution of each source when the user specifies the desired volume of the mix and the amount of source considered. This program, used with trial and error, eases computational complexity, as sources may contain more than one controlled macro-element.
Bright red bracts with white flowers are produced by H. angusta from Sept through Dec in Hawaii. The inflorescences are valued as cut-flowers and the species is potentially adaptable as a seasonal potted plant. Sakai et al (1990) reported the LD responsiveness of this species, but-additional detail was necessary to permit scheduling. EK's PhD thesis developed a model for flowering in which the minimum day length requirement to initiate was 13 hr for 7 wk with another 15-16 wk required for development irrespective of the day length (12-18 hr) or temperature (14-22C). As with other phozoperiodically sensitive heliconias, 3 unfurled leaves were required to respond to LD. A growing degree model was developed to determine the time necessary to reach the 3-leaf stage. A 30-year temperature record was used to estimate the latest shoot emergence date that would permit initiation, development, and flowering under Honolulu conditions. The model was validated by comparison with commercial production records. Sakai et al. 1990. Bul Heliconia Soc Intl 4(4):10-11
An aqueous solution of dikegulac-sodium at 0, 2000, 4000, 6000, or 8000 mg a.i./liter was sprayed on a mature Murraya paniculata hedge as the first leaves expanded on newly developing lateral shoots after trimming. The lateral shoots from each 0.09-m2 hedge surface elongated less and the coefficient of variation (cv) decreased as the growth regulator concentration increased. Application of dikegulac-sodium at 4000 mg a.i./liter to the most distal leaf on topped, single-leader seedlings inhibited the elongation of distal shoots while it enhanced proximal shoot growth. Dikegulac-sodium spray between 4000 and 6000 mg a.i./liter to the hedge decreased apical dominance among lateral shoots and enhanced uniform regrowth without causing visible damages. The cv reduction was attributed to the growth regulator-induced weakening of apical dominance. Chemical name used: sodium salt of 2,3:4,6-bis-O-(1-methylethylidene)-α-l-xylo-2-hexulofuranosonic acid (dikegulac-sodium).
In solution culture experiments, determining the quantity of nutrient sources to dispense in a solution mix is time consuming. When a source contains more than one controlled element (e.g., calcium nitrate [Ca(NO3)2]), a change made to control one element (Ca) requires an adjustment to the other element (N). To ease the computational chore, MacroMixer, an application program for mixing macro-nutrients, was developed using a spreadsheet for microcomputers.
MacroMixer consists of two parts. The first part computes the weight (volume for a liquid) of source necessary to give the target element concentration from each source. The second part computes the total concentration for each macro-element from a set of sources in the final mix. The total volume of the mix is specified at the beginning of program, but it can be changed later. Users can obtain a required weight for each source using the first part to use as a starting value in the second part. Adjustments are made among sources to achieve target element concentrations in the final mix.
The spreadsheet format hides computational formulae and constants for a clear view of solution composition; thus users are encouraged to exercise trial and error to achieve the most balanced mix. Using this program, we quickly formulated 13 mixes used in a 5 K-levels × 5 Ca-levels partial factorial experiment.
Abstract
Terminal cuttings of Protea neriifolia R. Br. gave earlier rooting and superior rooting index values when they received basal pretreatments of combinations of (2-chloroethyl)phosphonic acid (ethephon) at 300 ppm and indoleacetic acid (IAA) at 4000 ppm followed by a commercial rooting preparation composed of 1.0% indolebutyric acid (IBA) plus 0.5% NAA diluted 1:9 and combinations of 2500 or 4000 ppm butanedioic acid mono-(2, 2-dimethylhydrazide) (daminozide) with 4000 ppm of IBA or IAA. Treatment effects were evident after 3 and 4 months while the control required 5 to 6 months for similar rooting results.
Although in florescences of H. chartacea `Sexy Pink' can be harvested year'round in Hawaii, flowering is heaviest during the summer while demand is higher during winter months. The research was directed at identifying influences affecting the timing and rate of flower development, Dissection of apices of pseudostems which began development during June-July showed reproductive development (3-6 cm) in Jan-Feb when @6 leaves had unfurled. Some pseudostems had aborted the growing point after initiation had occurred. Data from 141 flowering pseudostems over 2 years of sampling showed that approx. 46 weeks were required from shoot emergence to flowering. Seasonal variation existed for leaf number and developmental period. The paper will analyze the influence of temperature on these two components of flowering.