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  • Author or Editor: Henry Donselman x
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Tissue culture labs based in countries with high labor costs are becoming more dependent on proprietary plants. This has increased the necessity of high profile plant breeding programs. Foliage and flowering plant breeding programs have evolved rapidly to take advantage of the benefits associated with tissue culture labs.

Breeding strategies and methods will be discussed on existing flowering and foliage programs for Anthuriums, Euphorbia, Aloe, Spathiphyllum, Homalomena, and Dieffenbachia. Embryo rescue in the lab has increased the survival of wide crosses from different species within a genera. Rapid multiplication of selected clones has increased the efficiency of screening for disease and insect resistance in the selection of new cultivars. Marketing, along with improved horticultural characteristics, determine the success of new releases.

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Abstract

Dracaena marginata Lam., grown continuously in full sun, produced an average of 4.3 basal branches per plant, while plants grown under 50% shade produced no basal branches. Acclimatized plants with a maximum number of shoots can be produced in 20-liter containers in 12 months by growing in full sun for 9 months to induce basal branching followed by 3 months in 50% shade for acclimatization.

Open Access

Abstract

The genus Heliconia (Heliconiaceae) consists of about 150 species of tropical herbaceous plants having banana-like foliage and ranging in height from 30 cm to 6 m. Some species have attractive reddish or multicolored foliage, making them useful tropical landscape plants.

Open Access

Abstract

West Indian mahogany [Swietenia mahagoni (L.) Jacq.] grown outdoors under 63% shade in southern Florida exhibited 3 distinct growth phases during the autumn and winter months. During the first phase (September through November), long-day conditions enhanced growth beyond that of natural daylength plants. In the 2nd phase (December through February), plants were essentially quiescent under both photoperiodic regimes in response to cool temperatures. In the 3rd phase (beginning in March), both long-day and natural daylength plants resumed growth at comparable rates. Thus, extending the photoperiod increases the growth rate in the autumn, but has little effect thereafter.

Open Access

Abstract

Ficus elastica Roxb. ex. Hornem. ‘Robusta’, F. benjamina L., Schefflera arboricola Hayata ex Kanehira, and Dracaena marginata Lam. were air-layered using 2 wounding methods. Rooting was best in double-slit F. elastica, but girdling produced a greater number of roots in the other 3 species. Girdling D. marginata stems induced coarse, unbranched roots, while a finer, more fibrous root system was produced on double-slit plants. Water conductivity through the wounded stem segments was reduced substantially in all 4 species by either form of wounding, with girdled stems having the lowest conductivities for S. arboricola and the 2 Ficus species.

Open Access

Abstract

Although nutrient deficiency symptoms for widely grown dicotyledonous crops are well-known and generally similar for a given element (5), deficiency symptoms of many elements on tropical monocotyledonous ornamental plants are unknown (4). Symptoms often differ dramatically among these taxa and may often be attributed to non-nutritional causes.

Open Access

Abstract

Extractability (in 1 n NH4OAc, pH 7.0) of Mg, Fe, Mn, Zn, and Cu from a Canadian peat, perlite, and sand medium amended with 6 commercial micronutrient fertilizer mixes was determined over an 80-week period with semi-weekly leaching. With the exception of Fe from FeDTPA, which dropped rapidly from very high levels to almost zero, and Fe from Esmigran, which was not extractable by NH4OAc, levels of all 5 elements from most fertilizer sources decreased slightly during the 1st month but then remained rather constant for the remainder of the 18 month experimental period. Extractable Mn, Zn, and Fe were reduced significantly by the superphosphate in Micromax Plus.

Open Access

Abstract

A series of experiments evaluated the effects of seed maturity, seed cleaning, gibberellic acid (GA3) or water presoaking, temperature, and planting depth on the percentage and speed of germination of Chrysalidocarpus lutescens H. Wendl. seed. Effects of temperature, cleaning, and storage container on the viability of stored C. lutescens seed were determined in another set of experiments. Germination was rapid and consistent when yellow to fully ripe seed was exposed to temperatures between 30° and 35°C. Cleaning seed is not essential if planting is done immediately. Presoaking seeds in 1000 ppm GA3 for 48 hr slightly accelerated germination speed, but caused excessive elongation of the resulting seedlings and was therefore not recommended. The best method for long-term storage of C. lutescens seed was to clean yellow to fully ripe seed, air-dry at 80% to 90% RH, treat with a seed protectant fungicide, and store at 23° in tightly sealed polyethylene containers. Optimum planting depth was dependent on the drying potential of the germination site.

Open Access

Abstract

The oleander aphid, Aphis nerii Fonscolombe, is a common pest of oleander, Nerium oleander L. Acephate, bendiocarb, chlorpyrifos, dimethoate, fenvalerate, methidathion, methomyl, permethrin, phosalone, and pirimicarb provided 100% control for 5 days after one spray application. Dimethoate, fenvalerate, methomyl, and pirimicarb provided additional residual control when plants were reinfested with aphids 5 days posttreatment.

Open Access