An experiment was initiated to evaluate the effects of previously recommended seed treatments for baldcypress [Taxodium distichum (L.) Rich.] or pondcypress [Taxodium distichum (L.) Rich. var. imbricarium (Nutt.) Croom] on Montezuma cypress [Taxodium distichum (L.) Rich. var. mexicanum Gordon], and to determine which, if any, provided optimum germination. Factorial combinations of seed treatments and stratification (2 °C for 0, 45, or 90 d) were applied to seeds of Montezuma cypress. Treatments included: 1) 90% ethanol 5 min soak, 2) ethyl ether 5 min soak, 3) 100 mg·L-1 citric acid 48 h soak, 4) mechanical scarification, 5) five hot water baths (42 °C) allowing the water to cool to room temperature between baths, and 6) a non-treated control. Three more seed treatments consisted of water soaks at room temperature (25 °C) for 0, 45, or 90 d. Seeds were germinated on moist filter paper in a growth chamber with a 12-h day/night photoperiod at a constant 25 °C. Data was collected daily for 14 d and then weekly for the following 4 wks. Radicle elongation of 1 cm was considered germination. Without stratification, 100 mg·L-1 citric acid and the hot water bath treatments were significantly different from other treatments by 7 d, though not from each other, with a mean cumulative germination of 15.6% and 12.2%, respectively. By 14 d, the 100 mg·L-1 citric acid treatment differed only from the ethyl ether wash attaining 28.9% and 14.4% germination, respectively. There were no other statistically significant differences observed among any other treatments without stratification. Germination percentages were low,<30%, without stratification. Effects of additional stratification will also be discussed.
Geoffrey C. Denny* and Michael A. Arnold
D. Creech and Yin Yunlong
There are three botanical varieties associated with the genus Taxodium: 1) Baldcypress (BC) = Taxodium distichum (L.) Rich.var. distichum, 2) Pondcypress (PC) = T. distichum var. imbricarium (Nutt.) Croom and 3) Montezuma cypress (MC) = T. distichum var. mexicana Gordon. Taxodium hybridization promises to combine the best characteristics of superior parents. In 1988, clones T302 (a BC × MC F1 hybrid), T401 (PC × MC), and T202 (PC × BC) were selected in China primarily for growth rate and tolerance to alkaline and salt-rich coastal floodplains. T302 is recommended in China for soils with pH 8.0∼8.5 and salt concentrations <0.2%. Other attributes of T302 included 159% faster growth than BC, good columnar form, longer foliage retention in fall and early winter, and no knees. T302 has been in the USA since January 2002 and is currently under evaluation in over 30 locations in southern USA. The clone was named `Nanjing Beauty' in 2004 as a cooperative introduction of the SFA Mast Arboretum and Nanjing Botanical Garden. In March 2005, the SFA Mast Arboretum received two new clones from China. T140 and T27 are considered more evergreen than T302 and both demonstrate strong salt tolerance. The clones were selected from a field population of T302 × TM—with strong TM characteristics and improvements in growth rate, salt tolerance, form and vigor. T140 grows faster than T27, which produces a wider profile. The foundation of the most recent selections comes originally from crosses made by Professor Chen and Liu in 1992 at the Nanjing Botanical Garden. Pollen from TM was applied to a female T302 and fifteen selections were made in 1995. The main characteristics for selection were 1) fast growth rate, 2) dark green color during the growing season and a red-orange leaf color in the fall, and 3) evergreen leaves. In 2006 or 2007, the results from T140 and T27 will be reported and registered with the Chinese Forestry Department. It will be at least five years before T140 and T27 enter commerce. In June, 2005 there were <100 each of these two clones. T118, T120 and T149 have already been registered with the Chinese Forestry Department at the provincial level, while T302 has been registered at the national level.
Larry J. Shoemake and Michael A. Arnold
Zea mays L. and Taxodium distichum L. seedlings were grown for 35 days in sand or 3:1 milled pine bark:sand media in 0.7 liter containers. Containers were painted on interior surfaces with 100 g Cu(OH)2/liter or 200 g Cu(OH)2/liter latex carrier (Spin Out™) or not. Five seedlings of each treatment combination were watered daily from 9.5 liter reservoirs with 100 ml of recycled fertilizer (20N-8.7P -16.6K. pH 6.0) solution initially containing 0.036 mg Cu/liter. Fertilizer solutions containing 0.036, 5, 10, 100, or 1000 mg Cu/liter were used to develop toxicity response curves with additional seedlings. Growth of both species in both media was increased by Spin Out treatments. Soluble Cu content of the recycled solution from Spin Out treated containers increased slightly (<1.2 mg/liter) during the experiment. Soluble Cu in leachate from Cu-treated containers ranged from 0.2 to 5 mg/liter with sand and from 0.30 to 1.2 mg/liter with bark. Soluble Cu in leachatc from non-treated containers ranged from 0.02 to 0.40 mg/liter with sand and 0.10 to 0.86 mg/liter for bark media.
Geoffrey Denny, Michael A. Arnold, and Donita Bryan
Seedlings from 15 open-pollinated families of Taxodium distichum (L.) Rich. native to the Gulf Coast, central and south Texas, and Mexico, were evaluated for growth and foliar chlorosis development on field sites in Texas with acidic to alkaline soils. Forty seedlings per family were rated for level of chlorosis, height, and trunk diameter after two growing seasons in the field. Families grown on acidic soils did not differ in chlorosis ratings. Families from Mexico and south Texas had the lowest levels of chlorosis in the field, followed by those from central Texas, and then those from the Gulf Coast. Additionally, eight of the families were subjected to a greenhouse screening experiment with four levels of KHCO3 (0, 4, 8, 12 mM). These were evaluated for height, trunk diameter, shoot and root dry mass, and level of chlorosis and leaf necrosis. Family differences were less apparent during greenhouse screening experiments than in the field. Mexican families were significantly less chlorotic than other families at higher levels of alkalinity in the greenhouse. There was also a trend for height and shoot dry masses of western populations to be less adversely affect by higher alkalinity levels than more eastern populations.
Louis B. Anella, Michael A. Schnelle, and Dale M. Maronek
Oklahoma Proven (OKP) is a plant promotion and evaluation program designed to help consumers choose plants appropriate for Oklahoma gardens. Aiding consumers with plant selection will lead to greater gardening success, enthusiasm, and increased sales for Oklahoma green industries. There are two major facets to the program: marketing, coordinated by Dr. Lou Anella, and evaluation, coordinated by Dr. Michael Schnelle. Plants to be promoted by OKP will be selected by an OKP executive committee based on recommendations from an OKP advisory committee comprised of industry professionals, cooperative extension specialists and educators, Oklahoma Botanical Garden and Arboretum affiliate members, and Department of Horticulture and Landscape Architecture faculty. Plants chosen for OKP must meet the following selection criteria: appropriate for gardens throughout the state of Oklahoma; readily available in the trade; limited input required, i.e. few pest or disease problems, tolerant of Oklahoma's diverse soil types and weather conditions; noninvasive; can be profitably produced. The OKP Advisory Board selected the following OKP Selections for 2000: Taxodium distichum; Spiraea japonica `Magic Carpet'; Verbena canadensis `Homestead Purple'; and Scaevola aemula. Promotional materials, such as posters and signs, will be available just after the first of the year, and the promotional push will begin in early March. Posters and signs will be distributed to retailers throughout the state free-of-charge and pot stakes and hang tags will be sold to wholesalers as a means of generating income for the Oklahoma Proven program. OKP plants will also be promoted through the television show “Oklahoma Gardening,” extension newsletters, and the press.
Michael A. Arnold and Daniel K. Struve
Seedlings of nine coarse-rooted species–sawtooth oak (Quercus acutissima Carruth), white oak (Q. alba L.), cherrybark oak (Q. falcata var. pagodifolia Elliott), post oak (Q. stellata Wangenh.), black walnut (Juglans nigra L.), pignut hickory [Carya glabra (Mill.) Sweet], pecan [C. illinoinensis (Wangenh.) C. Koch], Chinese chestnut (Castanea mollissima Blume), and common baldcypress [Taxodium distichum (L.) L. Rich]—were grown for one growing season in nontreated containers or in containers treated on their interior surfaces with white interior latex paint containing 100 g Cu(OH)2/liter. Seedlings of each species and container treatment were harvested twice: once after being transplanted from 3.2- to 15.0-liter containers and at the end of the growing season. Cupric hydroxide-treated containers decreased the amount of circled, kinked, and matted roots formed at the container wall-medium interface in all species tested. Plants grown in Cu(OH)2-treated containers also had altered root dry-weight partitioning. The partitioning patterns were species specific and included 6% to 20% increases in the percentage of root dry weight in interior vs. exterior portions of the rootball (white oak, black walnut, Chinese chestnut, and baldcypress), 10% to 21% increases in the percentage of root dry weight in upper vs. lower halves of the rootball (sawtooth oak, cherrybark oak, black walnut, and baldcypress), and an increase in the percentage of primary lateral roots (lateral roots originating from taproots or roots functioning as taproots) on the upper (proximal) half of taproots (cherrybark oak, pecan, and baldcypress). Nutrients in leaves, stems, and roots of sawtooth oak seedlings were analyzed at both harvests. Seedlings grown in Cu(OH)2-treated containers had more Cu in most plant tissues than nontreated seedlings. Also, seedlings grown in Cu(OH)2-treated containers had higher total Ca and Mg concentrations at transplanting and higher total N and Zn concentrations at the end of the growing season than nontreated seedlings.
Lenore J. Nash and William R. Graves
Responses of five bottomland tree taxa to drought and flooding were studied to identify those adapted to urban environments. During one experiment, containerized `Franksred' red maple [Acer rubrum L. `Franksred' (trademark = Red Sunset)], sweetbay magnolia (Magnolia virginiana L.), black tupelo (Nyssa sylvatica Marsh.), bald cypress [Taxodium distichum (L.) Rich.], and pawpaw [Asimina triloba (L.) Dunal.] were treated with various irrigation regimes for up to 118 days. Net assimilation rate (NAR) and relative growth rate (RGR) were reduced more by flooding than by drought for plants of all taxa, except pawpaw, which showed similar NAR and RGR during flooding and drought. Only sweetbay magnolia and bald cypress maintained positive NAR and RGR during flooding, and sweetbay magnolia was the only taxon that did not produce significantly less leaf surface area, shoot dry mass, and root dry mass during flooding and drought. Apparent morphological mechanisms of stress resistance included an increase in specific mass of leaves (mg·cm-2) during drought for red maple and bald cypress and a 385% increase in the root: shoot mass ratio for droughted plants of pawpaw. Leaf water relations of drought- and flood-stressed `Franksred' red maple and sweetbay magnolia were determined in a second experiment. Predawn and mid-day leaf water potential (ψ) decreased with decreasing root-zone matric potential for both taxa, and transpiration rate was reduced by drought and flooding. Pressure-volume analysis showed that leaves of `Franksred' red maple responded to drought by shifting symplastic water to the apoplast. Leaves of drought-stressed sweetbay magnolia adjusted osmotically by reducing osmotic potential (ψπ) at full turgor by 0.26 MPa. Our results suggest that sweetbay magnolia and bald cypress will perform well at urban planting sites where episodes of drought and flooding regularly occur.
Edward F. Gilman, Thomas H. Yeager, and Diane Weigle
Columns (4 × 15 cm) of incubated (25C, 7% volumetric moisture) milled cypress [Taxodium distichum (L.) L. Rich] wood chips received 180 mg of each ionic form of N applied to the surface from dry NH4NO3, KNO3, or (NH4)2SO4 and were leached daily with 16 ml deionized water (pH 5.5). After 10 days, >85% of applied N leached from the columns in all treatments. After 25 days, all N leached from the NH4NO3 and KNO3 treatments, and 93% leached from the (NH4)2SO4 treatment. In subsequent experiments, columns received 360 mg N from NH4NO3 and were leached daily with either 16, 32, 48, or 64 ml of deionized water for 50 days. The rate of N leaching increased with increasing water application rate, although total N leached per column was similar for all water rates after 25 days. Columns that received 45, 90, 180, or 360 mg N/column were leached daily with 16 ml of deionized water. Nitrogen concentrations in the leachate ranged from 3406 ppm
Michael A. Arnold, Don C. Wilkerson, Bruce J. Lesikar, and Douglas F. Welsh
Studies were conducted using Zea mays L. and Taxodium distichum L. seedlings as model systems to study Cu leaching from Cu(OH)2-treated containers. Initial experiments developed Cu toxicity curves (as CuSO4) in an inorganic (sand) or organic (bark-sand) medium with single (acute) or multiple (chronic) applications. A second pair of experiments investigated short-term (35 days) Cu accumulation and plant responses to irrigation with water (125 mL/plant per day) recycled through a fixed reservoir volume (9.5 L) from 0.7-L Cu(OH)2-treated containers filled with an inorganic or organic medium. Finally, plant responses and Cu leaching were monitored during growth in 2.3-L Cu(OH)2-treated containers filled with two organic media fertigated with high (8.0) or low (6.5) pH solutions. Different Cu(OH)2 concentrations and application methods were tested. Leachate data from the latter studies were used to calculate potential Cu concentrations in nursery runoff using various water application methods and pot spacings. Expression of Cu toxicity symptoms depended on exposure, concentration, and medium for each species. Plants subjected to chronic exposure and grown in an inorganic medium developed toxicity symptoms at lower doses than plants subjected to acute exposure and grown in an organic medium. Several measures of plant growth were greater for both species when grown in 0.7-L Cu(OH)2-treated containers, but not in 2.3-L containers. Plants in Cu(OH)2-treated containers seldom exhibited Cu toxicity symptoms in shoot tissues, even with an inorganic medium. Soluble Cu content of the recycled solution from Spin Out-treated containers increased slightly (<1.2 mg·L-1) during the 35-day experiment. Longer-term studies with nonrecycled leachate from 2.3-L containers indicated that Cu leaching increased after 60 to 90 days. Copper leaching was greater with the combination of applied solution of pH 6.5 and bark-sand-peat medium than with the combination of applied solution of pH 8.0 and bark-sand medium, and increased with greater concentrations of Cu(OH)2 in container wall treatments or when containers were filled before latex carrier was dried. Calculations of potential nursery runoff indicated that the levels of soluble Cu in effluent for most concentrations and spacings projected were below EPA action levels for potable water (1.3 mg·L-1) when overhead irrigation was used.
Qin Shi, Yunlong Yin, Zhiquan Wang, Wencai Fan, and Jianfeng Hua
distichum (L.), Taxodium ascendens , Taxodium mucronatum ( Tsumura et al., 1999 ). However, recent nomenclature places Taxodium as one species with three genotypes: T . distichum Rich. var. distichum (baldcypress-BC), T . distichum var