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Dissotis rotundifolia (Sm.) Triana and Tibouchina fothergillae ×pilosa are members of the Melastomataceae family with high ornamental potential. The growth habits of these species are not ideal for nursery production or shipping. D. rotundifolia grows rapidly and needs frequent pruning. T. fothergillae ×pilosa has an open growth habit and could benefit from a more compact form. The effect of the plant growth regulator (PGR) paclobutrazol on D. rotundifolia and T. fothergillae ×pilosa was assessed to determine whether it could produce plants with a more compact growth habit. Paclobutrazol was applied as a drench and a spray. Drench application was more effective in reducing the growth of both species. Spray application was effective in reducing the growth of D. rotundifolia but was not effective on T. fothergillae ×pilosa. Neither drench nor spray application delayed or reduced flowering in D. rotundifolia. T. fothergillae ×pilosa did not flower during the study. For both D. rotundifolia and T. fothergillae ×pilosa, neither drench nor spray application had an effect on root dry weight. Low-to-medium dosages were effective at controlling plant growth in D. rotundifolia and T. fothergillae ×pilosa without adverse effects on plants. Drench treatments have more persistent effects on plant growth than spray treatments.

Seed germination within Abelia R. Br. spp. has been described as slow and inconsistent. An experiment was conducted with seeds of Abelia ×grandiflom (André) Rehd. (glossy abelia) to test procedures to increase germination percentage, uniformity and rate. The effect of pericarp removal was examined on seeds with no additional treatment, and on seeds that were stratified (moist-prechilled) for 60 days at 4C (39F) or immersed in 100 mg/liter gibberellic acid for 24 hr. Treatments were replicated five times with 15 seeds per replication. Seeds were sown on sphagnum peat, and germinated under mist in a greenhouse. Weekly germination counts were recorded for 8 weeks. Seeds with intact pericarps germinated at a significantly higher percentage than those without pericarps. Stratified seeds germinated in fewer days than the other treatments. The combination of stratified seeds with intact pericarps gave the best overall response, with final germination of 62% and a reduction in germination time to 14 days (to reach 90% final germination) as compared to 35 days for untreated seeds.

Epicuticular lipids were extracted from the foliage of six deciduous and one evergreen azalea genotypes (Rhododendron sp.) and identified by gas chromatography-mass spectrometry. The relationship of leaf-surface lipid composition with measures of resistance to azalea lace bug, Stephanitis pyrioides Scott, was evaluated. Each genotype had a distinct epicuticular lipid composition. The major surface lipid components from all test taxa were n-alkanes and triterpenoids. In the most resistant genotypes [R. canescens Michaux and R. periclymenoides (Michaux) Shinners] ursolic acid, n-hentriacontane, and n-nonacosane were the most abundant epicuticular lipids. The lipids present in largest proportion among all susceptible deciduous genotypes tested were α-amyrin, β-amyrin, and n-nonacosane. The proportions of the lipid components from the same plant of each genotype varied between spring and fall samples. Among classes of lipids, n-alkanes, n-1-alkanols, and triterpenoids had significant correlations with azalea lace bug behavior on host plants. Among individual components, heptadecanoic acid, n-hentriacontane, oleanolic acid, ursolic acid and one unknown compound (with major mass spectra 73/179/192/284/311) were significantly negatively correlated with host plant susceptibility to azalea lace bug, as measured by oviposition, leaf area damaged, egg and nymphal development, and nymphal survivorship. Triacontanol, α-amyrin, β-amyrin, and three unknowns were significantly positively correlated with host plant susceptibility. Acceptance or rejection by azalea lace bug to a particular plant may be mediated by a balance of positively and negatively interpreted sensory signals evoked by plant chemicals. This study indicated that the high levels of resistance observed in R. canescens and R. periclymenoides may be due to the lesser amount or the absence of attractants and stimulants for feeding or oviposition.

A comparison of semi-solid vs. liquid embryo proliferation media was made using two Gossypium hirsutum L. genotypes (Coker 312 and T25) and two callus initiation media. Sections of petioles from mature, flowering plants were cultured on two modified Murashige and Skoog media. Medium 1 included 4.0 mg l-1 NAA and 1.0 mg l-1 kinetin; medium 2 contained 0.1 mg l-1 2,4-D and 0.1 mg l-1 kinetin. After six weeks, callus was removed from each explant and divided in half. One callus portion was placed in liquid proliferation medium and the other on semi-solid (0.2% Gelrite) proliferation medium. Composition of proliferation medium was identical to that of initiation medium, except no growth regulators were added. Embryos were counted after eight weeks. The percentage of explants forming callus was influenced by genotype/initiation medium combination. Analysis of variance procedures revealed significant variability for callus initiation media, proliferation media (semi-solid or liquid), and an initiation medium x genotype interaction. Paired t-tests indicated that more embryos were produced in liquid proliferation medium (227.3 embryos/culture) than on semi-solid proliferation medium (134.6 embryos/culture).

Three commercial varieties (Acala SJ-5, Coker 312 and Paymaster 303) and three exotic accessions (T1, T25 and T169) of cotton (Gossypium hirsutum L.) were tested for ability to undergo somatic embryogenesis. Sections of split petiole were cultured on 3 media and evaluated for embryogenesis after 180 days. Embryogenic T25 and Coker 312 plants were selected and crossed in a diallel with non-embryogenic Acala SJ-5, Paymaster 303, T1 and T169 plants. F1, F2 and BC1 populations were generated and tested for embryogenesis on a medium of MS salts and vitamins (1962) plus (per liter) 4.0 mg NAA, 1.0 mg Kn, 30 g glucose, 100 mg myo-inositol, 2.0 g Gelrite and 0.75 g MgCl2. Segregation for both occurrence and magnitude of embryogenesis was observed, suggesting the action of more than one gene.

Immature leaf laminae and petioles of `Regale' and `Fry' muscadine grapes (Vitis rotundifolia Michx.) were cultured on Nitsch and Nitsch (NN) medium supplemented with 9.0 μm 2,4-D and 4.4 μm BA, and gelled with agar. Callus and original explant tissues were transferred to NN medium containing 10.7 μm NAA and 0.9 μm BA to proliferate embryogenic callus, which, when transferred to NN medium without growth regulators, yielded globular embryos. The embryos matured and germinated after being subcultured to fresh medium without growth regulators. Somatic embryogenesis incidence was greater from petioles than laminae: 90% of `Regale' and 50% of `Fry' petioles formed embryos, compared with 14% and 2% of laminae, respectively. Culturing germinated somatic embryos on NN medium with 1 μm BA enhanced shoot growth. Regenerated plants flowered and appeared morphologically normal. Chemical names used: N-(phenylmethyl)- 1H -purin-6-amine (BA); 2,4-dichlorophenoxyacetic acid (2,4-D); α- naphthaleneacetic acid (NAA).

A regeneration system for 'Pumila' pampas grass (Cortaderia selloana Schult.) that yields plants over many months and allows control of morphogenesis was developed. Immature inflorescence explants cultured for three 4-week passages on MS basal medium supplemented with 4.5 μM 2,4-D and 8.9 μM BA yielded a dark green callus that organized into shoot primordia. Rate of shoot development was increased after transfer of shoot primordia to medium supplemented with 9.8 μM IBA. Subculture every 4-6 weeks onto medium containing IBA yielded a continuous production of shoots. Control of morphogenesis was achieved by transferring cultures to medium containing 4.5 μM 2,4-D and 8.9 μM BA for shoot bud proliferation and to medium containing IBA for shoot production.

Nodes from in vitro grown shoots of `Regale' and `Triumph muscadine grape (Vitis rotundifolia) were cultured in 25 × 95-mm glass vials, 25 × 150-mm glass culture tubes, 55 × 70-mm glass baby food jars and 100 × 25-mm plastic petri dishes. Culture medium consisted of Murashige and Skoog salts and vitamins, 80 mg/l adenine sulphate, 170 mg/l sodium phosphate, 2 mg/l BA and 8 g/l agar. Amount of medium dispensed was 8 ml per vial, 18 ml per culture tube and jar, and 70 ml per petri dish. Containers were covered with clear plastic lids, sealed with parafilm, and placed under fluorescent lights for six weeks. The number of shoots per explant that formed in petri dishes was three to four times greater than those formed on explants in vials, tubes and jars. However, the number of nodes per shoot were fewer in dishes than in the other containers. Callus formation was excessive in jars to the detriment of shoot production. Vials and tubes had small amounts of callus, while little or no callus was observed in dishes.

Screening of muscadine grape (Vitis rotundifolia) plants in vineyards has revealed that many plants carry Xylella fastidiosa; under suitable conditions, this bacterium causes Pierce's disease which can result in considerable loss. To determine whether propagation of muscadine through shoot tips would eliminate X. fastidiosa, plants were injected with this bacterium. After demonstrating infection, shoot tips were collected and cultured. according to the technique of Barlass and Skene (1978). Plants which were regenerated were found to be free of the bacterium. To determine whether this shoot-tip culture technique would be effective for propagation of a diverse group of muscadines, 19 cultivars were tested. Three of the cultivars failed to produce any plants, and several others reproduced at a low rate of efficiency. In an attempt to improve the rate of regeneration, several modifications to the technique were tested. For most cultivars, better initiation occurred on liquid medium, more shoots were produced with BA than with 2iP, and the addition of adenine sulfate and sodium phosphate improved the regeneration frequency.

A factorial experiment was performed to develop a medium which would support initiation and proliferation of callus in a diverse group of exotic lines of Gossypium hirsutum. Seed hypocotyls of T1, T25 and T133 were cultured on Linsmaier and Skoog (LS) basal medium (1965) with NAA or 2,4-D tested in combination with BA or kinetin. The best medium from this study was then compared to five published media for support of callus initiation and growth of the varieties Acala 1517-75, Coker 500, Dunn 120, Paymaster 303 and TM1. Furthermore, the effects of two gelling agents, Difco-Bacto agar and Kelco Gelrite, were investigated with each of the six media. Significantly more callus was initiated on media solidified with Gelrite than with agar. The best callus production occurred on LS medium supplemented with 30gl-1 glucose, 0.1 mgl-1 BA and 0.1 mgl-1 2,4-D.