A survey of 16 cut evergreen species found six clustered groupings of species based on ethylene production at 2 and 21C. Ethylene production (in nanoliters per kilogram of fresh weight per hour) at 21C ranged from 26 for Juniperus virginiana to 2800 for Sequoia sempervirens. Exposure to 0.1 or 1.0 ppm ethylene for 72 hours at 2C resulted in minor effects on two species, while significantly delaying senescence of Sequoia sempervirens. Silver thiosulfate (STS) pretreatment decreased or increased longevity of six species, but all effects were minor. Longevity of cut evergreens when held in preservative solution ranged from 14 days for Pinus sylvestris to 56 days for Chamaecyparis lawsoniana. Senescence symptoms observed were needle abscission, desiccation, and/or chlorosis.
Dwight R. Tingley and Timothy A. Prince
Jianhua Li, Jeremy Ledger, Peter Del Tredici, and Donglin Zhang
The identity of heath-leaved cypress is controversial. In this study nucleotide sequences of nuclear ribosomal DNA were used to identify heath-leaved cypress (Chamaecyparis `Ericoides') species. Sixteen individuals were sampled representing the five species of Chamaecyparis, `Ericoides', and four other genera of Cupressaceae (Cupressus, Fokienia, Juniperus, and Thuja). The results placed `Ericoides' unequivocally to Chamaecyparis thyoides, supporting a conclusion derived from wood anatomy. This study supports the usefulness and integrity of using molecular data to identify the genetic affinity of cultivars that are morphologically different from the parent species.
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.
Franco Tognoni and Roberto Lorenzi
The acid phase of methanolic extracts of Picea glauca var. albertiana cv. Conica tissue, a difficult-to-root cultivar, had a high content of substances, at Rf 0.9 – 1.0, which inhibited the growth of Avena first internode. Chamaecyparis lawsoniana var. fletcheri, an easy-to-root variety, had a lower content of these substances. The substances stimulated root formation in mung bean cuttings, but no synergistic root-promoting effect was found when they were supplied to mung bean cuttings in the presence of 5 × 10−6M indoleacetic acid (IAA).
The substances at Rf 0.9 – 1.0 showed a dose-response effect over a concn range of 0 to 1.106 g fresh wt. Concn higher than 1.106 g did not further increase the number of roots in either species. An additive effect between extract and IAA was found in Picea at concn below 0.276 g and in Chamaecyparis at concn lower than 0.110 g and higher than 1.106 g fresh wt. The possibility that root initiation may be determined by hormone balance rather than a single substance is discussed.
Barbara Gilmore, Nahla Bassil, April Nyberg, Brian Knaus, Don Smith, Danny L. Barney, and Kim Hummer
( Jennings et al., 2011 ). For example, Illumina, Inc. (San Diego, CA) sequencing has been used to develop SSR markers for port-orford cedar ( Chamaecyparis lawsoniana ) and alaska yellow cedar ( Callitropsis nootkatensis ) ( Jennings et al., 2011 ), and for
Hye-Ji Kim and Xinxin Li
container crop production ( Wright and Niemiera, 1987 ). P applications of ≈10 mg·L −1 in the irrigation water have resulted in maximum growth of Ilex crenata ( Yeager and Wright, 1982 ) and Chamaecyparis lawsoniana ( Van der Boon, 1981 ), which was