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  • Author or Editor: R.A. Sink x
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Abstract

Tissue culture propagation of Dicentra spectabilis (L.) Lem. was achieved by proliferation of 2.0- to 2.5-cm-long shoot tips placed on solidified Murashige and Skoog (MS) salts and vitamins medium containing 2.0 mg/liter kinetin. Each shoot tip yielded a 50-fold increase within 6 weeks. Proliferated shoots rooted 100% in 25 days on MS medium containing selected levels of either indolebutyric acid (IBA) or naphthaleneacetic acid (NAA). Optimum transfer of rooted shoots to the greenhouse occurred when an initial high humidity was followed by a gradual reduction over 5–7 days in the ambient environment.

Open Access

Abstract

Two evergreen azalea clones, Rhododendron × ‘Maryann’ and R. poukhanense Levl., were studied in outdoor and controlled freezing experiments during 2 winters. Outdoor experiments revealed that 1) flower bud injury occurred in mid-winter, 2) flower buds of R. poukhanense were less hardy than those of R. ‘Maryann’, 3) splitting of apical stems often accompanied injury in R. poukhanense, and 4) a significant difference existed between the 2 clones in apical stem water percentage during December and January. In the laboratory freezing tests, initial injury occurred in the apical stem pith and at a higher temp than that which injured the flower bud. When twig water content of R. poukhanense was reduced prior to freezing, stem splitting was prevented and the twigs survived exposure to lower temp. Large ice masses were observed in the vascular tissue of R. poukhanense when the frozen twigs were sectioned. Water content and ice crystal development were the primary factors affecting survival of both clones.

Open Access

Use of groundcovers in the landscape is often limited due to their slow establishment rate compared to that of turf. Hedera helix L., (English ivy), Euonymus fortunei `Coloratus' (Turcz.) Hand.-Mazz. (purpleleaf wintercreeper euonymus), and Liriope spicata Lour. (creeping lily-turf) were evaluated in a full sun and 50% shade environment to determine the effects of fertilizer applications on their establishment and growth. Fertilizer treatments, of 13N-13P-13K at a rate of.45 kg/93 m2, used were: 1) at planting only; 2) at planting and once during the summer; 3) at planting, in summer, and once in the fall; or 4) at planting, in summer, in fall, and once the following spring. Data collected included fresh and dry weight comparisons of pruned material, percentage canopy cover, plant quality and vigor by visual assessment and photographs, and time required for maintenance of each plot. Results show limited fertilizer effects and interaction according to species during the first several months of growth. Establishment and survivability of Hedera was influenced mainly by light exposure rather than fertilizer applications. There was no difference in establishment rates between Liriope and Euonymus, however, under shade, Euonymus did not develop its characteristic fall color. Hedera was established in one season under 50% shade and can be considered very competitive with turf under the same conditions.

Free access