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Len Burkhart, Martin Meyer Jr., and S. Dorner Dr.

Rooting of shoots from in vitro culture of most conifers can be difficult. An antigibberellin, ancymidol, has been shown to promote rooting of in vitro proliferated shoots of asparagus clones, but it has not been tested on conifers. Ancymidol and flurprimidol was tested for rooting on established cultures of Lake States white pine (Pinus strobus). Pulse treatments containing 5 uM ancymidol and 0.5 uM NAA gave 43% rooting, while pulse treatment with 0.5 uM NAA resulted in 7% root formation. Flurprimidol also stimulated root formation on white pine shoots, but was less than ancymidol. Thuja occidentalis `Hetz's Wintergreen' formed roots on 87% of in vitro proliferated shoots when given a pulse treatment with 5 uM ancymidol and 50 uM NAA. Shoots initiated an average of 10 roots after 60 days on vermiculite containing 1/2 liquid MCM medium.

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Len Burkhart, Martin Meyer Jr., and S. Dorner Dr.

Rooting of shoots from in vitro culture of most conifers can be difficult. An antigibberellin, ancymidol, has been shown to promote rooting of in vitro proliferated shoots of asparagus clones, but it has not been tested on conifers. Ancymidol and flurprimidol was tested for rooting on established cultures of Lake States white pine (Pinus strobus). Pulse treatments containing 5 uM ancymidol and 0.5 uM NAA gave 43% rooting, while pulse treatment with 0.5 uM NAA resulted in 7% root formation. Flurprimidol also stimulated root formation on white pine shoots, but was less than ancymidol. Thuja occidentalis `Hetz's Wintergreen' formed roots on 87% of in vitro proliferated shoots when given a pulse treatment with 5 uM ancymidol and 50 uM NAA. Shoots initiated an average of 10 roots after 60 days on vermiculite containing 1/2 liquid MCM medium.

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A.M. Wagner and J.T. Fisher

Dormancy level is an important factor in rooting stem cuttings of conifers. Eldarica pine, a Mediterranean species, is a multiple flushing pine that does not appear to express endodormancy in southern New Mexico. Photoperiod manipulations can alter the dormancy level of some conifer species; however, effects on eldarica pine are unknown. Half-sib stock plants were randomly assigned to one of three photoperiods: natural daylength (>12 hours, control), long-term (7 months) exposure to 9-hour daylength (LTSD), and 2-week exposure to 9-hour daylength (STSD). Of the cuttings from LTSD stock plants, 78% rooted; however, only 67% of the cuttings from the other two treatments rooted. Differences in rooting also were related to shoot type of the cuttings. Cuttings from expanded short shoots without a bud rooted more frequently than cuttings from branch shoots with or without a bud present. Applications of these results are discussed.

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G.E. Jones and B.M. Cregg

Conifers represent a sizeable portion of nursery and landscape sales in the upper midwestern U.S. Several conifer species have been overplanted to the point where disease problems and insect pressures have developed. Although more than 40 true fir (Abies Mill.) exist throughout the northern hemisphere, use of firs in the landscape and Christmas tree industry has been limited to relatively few species. This is largely due to perceived intolerance of many site conditions. However, recent research suggests Abies are more tolerant of varying site conditions than originally thought. Successful introduction of new exotic fir species for landscape use will require a systematic approach to identify species that are adapted to environmental stresses. In this article we review the extent and nature of inter-specific variation among Abies species in traits commonly associated with tolerance of stresses found in the upper midwestern U.S. Specifically, we focus on cold hardiness, budbreak, photosynthetic gas exchange and water relations, and response to soil pH. It is important to match plants possessing necessary adaptive characteristics with the existing site conditions. Therefore, multiple screening factors should be met when identifying species or trees from different provenances for future introduction.

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M.W. Duck, B.M. Cregg, R.T. Fernandez, R.D. Heins, and F.F. Cardoso

Tabletop Christmas tree growers whose greenhouse-grown conifers have undesirable shoot growth may alleviate this problem by applying plant growth retardants (PGRs). Some of the most common PGRs in the horticulture industry were evaluated to determine their effectiveness in controlling plant height: ancymidol at 100 μL·L-1 (ppm), daminozide at 5000 μL·L-1, paclobutrazol at 60 μL·L-1, chlormequat at 1500 μL·L-1, uniconazole at 15 μL·L-1, and ethephon at 500 μL·L-1 compared to a nontreated control. The following conifer species were used: colorado blue spruce (Picea pungens), black hills spruce (P. glauca var. densata), serbian spruce (P. omorika), noble fir (Abies procera), grand fir (A. grandis), fraser fir (A. fraseri), concolor fir (A. concolor), arborvitae (Thuja occidentalis), port orford cedar (Chamaecyparis lawsoniana), and douglas-fir (Pseudotsuga menziesii). Chlormequat was the only PGR that caused phytotoxicity and damage to the foliage was minimal. Noble fir, douglas-fir, colorado blue spruce, and arborvitae were unaffected by any PGR treatment. Daminozide reduced growth of port orford cedar and concolor fir; uniconazole reduced growth of black hills spruce and serbian spruce; paclobutrazol reduced growth of fraser fir; and ethephon reduced growth of grand fir.

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Bruce A. Kimball, Dale L. Nolte, and Kelly B. Perry

Hydrolyzed casein (HC) and retail products that contain HC are evaluated as repellents to minimize deer damage to trees and shrubs. Three different experiments demonstrate that HC is an effective deer repellent. Technical-grade HC completely eliminated browse damage to evergreen shrubs (Gaultheria shallon Pursh.) and conifers (Thuja plicata Donn.) during the test periods. Retail sources of HC (concentrated baby formula powders) are not as effective as pure hydrolyzed protein, but do offer browse protection when alternative sources of browse are available. For nursery, orchard, and reforestation applications, HC is a promising deer repellent to minimize losses due to browse. For the private homeowner, a simple repellent formulated with glue and a HC-containing baby formula may offer considerable browse protection when alternative forage is available.

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Russell Pressey

Polygalacturonase (PG) in higher plants has been considered to be associated with ripening fruits although it is now known to be present in foliage and storage organs. We recently found very high levels of PG in some grass pollens (Plant Science 59, 57-62, 1989). This prompted an examination of other pollens for PG activity. All of the pollens analyzed contained PG but the range of activities was great. Eastern cottonwood pollen contained the most PG, with a level about 12 times higher than that usually found in ripe tomato fruit. Pollens from the other members of Populus were generally high in PG. Pollens from the oak family also contained very high PG, with the highest amount in white oak pollen. Pollens from pecan, English walnut, willows, birch and hickories contained moderate levels of PG. The lowest amounts of PG were found in pollens from beech, sycamore and conifers. The PG's from the two richest sources (eastern cottonwood and white oak pollens) were partially purified and characterized. Both enzymes were found to be exopolygalacturonases that require Ca2+ for activity. PG may be involved in some function related to pollination but an explanation for the wide range of activities indifferent pollen is not obvious.

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Russell Pressey

Polygalacturonase (PG) in higher plants has been considered to be associated with ripening fruits although it is now known to be present in foliage and storage organs. We recently found very high levels of PG in some grass pollens (Plant Science 59, 57-62, 1989). This prompted an examination of other pollens for PG activity. All of the pollens analyzed contained PG but the range of activities was great. Eastern cottonwood pollen contained the most PG, with a level about 12 times higher than that usually found in ripe tomato fruit. Pollens from the other members of Populus were generally high in PG. Pollens from the oak family also contained very high PG, with the highest amount in white oak pollen. Pollens from pecan, English walnut, willows, birch and hickories contained moderate levels of PG. The lowest amounts of PG were found in pollens from beech, sycamore and conifers. The PG's from the two richest sources (eastern cottonwood and white oak pollens) were partially purified and characterized. Both enzymes were found to be exopolygalacturonases that require Ca2+ for activity. PG may be involved in some function related to pollination but an explanation for the wide range of activities indifferent pollen is not obvious.

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David Creech, Greg Grant, and Dawn Parish

The SFA Mast Arboretum began as a landscape plant materials class project on the south side of the Agriculture building in 1985. In 2000, over 20 theme gardens now occupy 18 acres. The garden is computer mapped and an accessioning system is in place. Theme garden developments include daylilies, herbs, a rock garden, a xeriscape, plants for shade, wetland, and bog conditions, a line of vines, an Asian Valley, conifers and hollies, and numerous gardens that trial and display herbaceous perennials. Recent developments include a children's garden and, the biggest project to date, an 8-acre SFA Ruby Mize Azalea garden, with a grand opening in Apr. 2000. Theme gardens are utilized to display collections. Significant assemblages include Rhododendron (400 cultivars and selections), Acer (168 cultivars), Camellia (210 cultivars), Loropetalum (18 taxa), Cephalotaxus (43 taxa), Magnolia (47 taxa), Abelia (37 taxa), Ilex (73 taxa), and others. Plant performance and observational information is recorded. Second author Grant has numerous plant introductions in the past 5 years, many that are well represented in the nursery industry and recognized by TAMU's Coordinated Educational and Marketing Assistance Program (CEMAP) as “Texas Superstar” promotions (trademarked). SFA Mast Arboretum plants are promoted via distributions, trade articles, and the Arboretum's website: www.sfasu.edu/ag/arboretum.

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Donglin Zhang, Michael A. Dirr, and Robert A. Price

Cephalotaxus species are needle evergreens offering the aesthetic qualities of Taxus, yew, yet are heat- and drought-tolerant, sun- and shade-adaptable, and resist deer browsing. They are adaptable to nursery and garden cultivation in USDA hardiness zones (5)6–9. Unfortunately, the various species are frequently confused in the American nursery trade due to their extreme similarity in morphology. Recently, molecular data have been widely applied in the taxonomic studies, especially DNA sequencing. The chloroplast gene rbcL of Cephalotaxus has been sequenced for determining species relationships. The preliminary results show that C. oliveri Mast. has 10 base changes from C. drupacea Sieb. et Zucc., while only one base difference occurred between C. drupacea and C. harringtonia (Forbes) Koch. There are between one and 10 base substitutions among C. fortunei Hooker, C. koreana Nakai, and C. sinensis (Rehd. et Wils.) Li. Compared with other closely related conifers, Cephalotaxus has a substantial number of differences among species except between C. drupacea and C. harringtonia, which may not be distinct species. Detailed data relative to gene sequencing, growth morphology, and horticultural characteristics should lead to correct identification of species and great horticultural uses. Furthermore, the method of rbcL sequence can be applied to distinguish other morphologically homogeneous ornamental plants.