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  • Author or Editor: John M. Englert x
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In recent years the use of native plant materials for conservation and revegetation projects has received increased awareness and interest. The National Plant Materials Center (NPMC), in cooperation with the USDI-National Park Service, is involved in the revegetation of disturbed areas within our National Parks using native herbaceous and woody plants. This involves the collection of germplasm from selected niches within the Parks, an increase in seed and production of transplants, and reestablishment of native communities in natural areas.

One major focus of the program is to develop technology for improving native plant propagation and production, which should make the use of native plants more viable in the commercial sector. Germination of species of Tridens, Dichanthelium, Danthonia, Helianthus, Schizachyrium, and Andropogon has been improved to 80-95% by altering the germination environment. Production of these species in plugs has also been streamlined to maximize space efficiency and provide cost-effective methods for planting native grasses and wildflowers.

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The germination of ericaceous plant species is often variable and not well-defined. We have had some difficulty in obtaining good germination and significant establishment and growth after transplanting. Four different moisture regimes and two different media were used for the germination of Kalmia latifolia, Oxydendrum arboreum, Rhododendron maximum, and Vaccinium corymbosum seeds. Seeds were surface-sown on peat or peat + bark (1:4) media. Pots were then placed under either one of two different misting regimes, set in a tray of water, or set in a tray of water under a humidity tent. Germination was higher and more consistent for all species sown on peat and occurred sooner for seeds under the humidity tent. Rhododendron and Kalmia under the humidity tent grew more rapid than with other treatments. Increases in germination under the humidity tent were due more in part to higher temperatures than to the minimal increase of humidity inside the tent. Germination was poor for seeds under the high-mist treatment, presumably because there was too much moisture. Germination of Vaccinium and Oxydendrum was low for all treatments.

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Desiccation stress during the postharvest handling of bare-root nursery plants is often responsible for poor performance after transplanting. Alternate methods of handling desiccation sensitive deciduous trees, such as Washington hawthorn (Crataegus phaenopyrum Med.), and herbaceous perennials species, including Iris, Hosta, and Hemerocallis, are needed for improving survival after transplanting.

A new antidesiccant compound called Moisturin has been useful in reducing water loss from Washington hawthorn trees during storage and shipping, and in improving survival and plant performance during establishment. Hawthorn seedlings or multi-stemmed trees treated with Moisturin before a period of water stress had up to 75% less dieback than control or other antidesiccant treatments.

The use of Moisturin treatment and / or protection with plastic bags of topped bare-rooted herbaceous perennials before five weeks of cold storage (2C) was effective in improving the survival of Iris ensata, Iris sibirica, and Hosta plants. Hemerocallis plants survived equally well with all treatments. The greatest effect on reduction of water loss and improvement of survival was when plants were sealed in plastic bags.

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A 32kDa bark storage protein (BSP) which accumulates in the fall and is degraded in the spring has been identified in Populus deltoides bark. The BSP gene has been shown to be regulated by short day (SD) photoperiod (8 h). The physiological condition of the plant and the environmental factors necessary for the degradation and retranslocation of BSP are of considerable interest for determining the role of this protein in the remobilization of nitrogen in trees.

Poplar plants were placed in a SD growth chamber for 4 or 7 weeks to induce growth cessation (bud set) or dormancy, respectively. BSP accumulated to high levels in bark tissues after 3 weeks SD and remained high through 7 weeks SD. Plants in which growth had stopped (4 weeks SD), or in which dormancy (7 weeks SD) was broken with hydrogen cyanamide (0.5 M) or chilling (4 weeks 0C) broke bud within 1 week of being placed into long day (LD) conditions. Dormant plants which were not chilled broke bud after 3 weeks LD. BSP levels decreased around the time of budbreak, suggesting that the degradation of BSP is dependent on the need for a nitrogen sink, ie. budbreak and new shoot growth.

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Desiccation stress during the postharvest handling of bare-root deciduous trees can account for dieback and poor regrowth after transplanting. Desiccation tolerance of three bare-root deciduous hardwood species was determined at monthly harvest intervals from Sept. 1990 through Apr. 1991. Among the three species tested red oak (Quercus rubra L.) was most tolerant to desiccation, followed by Norway maple (Acer platanoides L.) and Washington hawthorn (Crataegus phaenopyrum Medic.). Maximum desiccation tolerance of all three species occurred during the January and February harvests. Of 20 film-forming compounds tested, the antidesiccant Moisturin was the most effective in reducing water loss from bare-root trees during desiccation stress and in improving survival and plant performance during re-establishment in the laboratory, greenhouse, and field. Moisturin-treated plants lost up to 80% less water than untreated plants. Washington hawthorn seedlings treated with Moisturin before severe desiccating conditions had the highest survival, lowest dieback/plant, and highest root growth ratings. The results indicate that Moisturin is an effective means of overcoming postharvest desiccation stress in desiccation sensitive plants, such as Washington hawthorn.

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