The soil in south Miami–Dade Co., Fla., consists of 4 to 6 inches of scarified limestone, officially a “very gravelly loam”. The bedrock reaches the surface; with little weathered material or organic matter. Heavy equipment is used to break up the rock, and a rock plow is used every few years to prevent re-compaction. Street trees in swales are installed in shallow holes dug in the rock and back-filled with crushed limestone. Golden trumpet tree, or yellow tab, Tabebuia chrysotricha, and copperpod, Peltophorum pterocarpum, are deciduous, tropical trees of medium size. Both are popular throughout south Florida because they produce spectacular displays of yellow flowers before the leaves emerge in the spring. When planted on rockland soil, both species present maintenance problems which suggest that they may not be good choices for use as street trees. In Summer 2005, after three hurricanes, both species were evaluated for long-term survival. Of 246 Tabebuia, 26% fell, 18% leaned (or 45% damaged), and 25% were missing, having been destroyed in previous years. Only one was broken, the rest fell due to root failure. Six large trees growing near buildings were standing. It appears that yellow tab is not a good street tree in rockland, not even for the short-term. Of 142 Peltophorum, 23% fell, 3% leaned (or 26% damaged), and 4% were missing. Due to an umbrella-like branching pattern, 15% had branches broken on the street side, caused by vehicles, not wind. Though it sustained only half the wind damage of yellow tab, copperpod is not a good street tree, due to poor branching patterns.
Joe Garofalo and Ruben Regalado
Amy Douglas and Rosanna Freyre
Nolana is a diverse genus native to coastal deserts of Peru and Chile, with great potential for developing new ornamental cultivars. Low germination has been an obstacle to breeding efforts at the University of New Hampshire (UNH). Nolana fruits are comprised of unusual sclerified mericarps, each containing one or more embryos. Germination occurs with opening of funicular plugs on the mericarps. Under normal greenhouse conditions at UNH, germination success in eight Nolana species (N. adansonii, N. aticoana, N. humifusa, N. laxa, N. ivaniana, N. plicata, N. elegans, and N. rupicola) ranged from 0 to 0.05 seedlings/mericarp. We analyzed mericarp morphology, imbibition, and the effect of chemical and environmental germination treatments. SEM showed that soaking treatments create physical changes in mericarp morphology, exposing tracheid tubes in the funicular plugs. Mericarps were soaked in dye to track imbibition, confirming that this occurs through the tracheid tubes, and that additional scarification is not required. The following chemical treatments were unsuccessful in increasing germination: 0.1 N HNO3, 0.2 KNO3, conc. H2SO4, 10 mM or 1 μM ethephon. Gibberellic acid (1000 ppm) effectively increased germination in some species (up to 0.47 seedlings/mericarp). Mericarps stored dry for 2 years had significantly higher germination than fresh mericarps (0.55 seedlings/mericarp). Mericarps of N. aticoana were subjected to after-ripening treatments. Mericarps stored for 7 weeks at 35 °C and 75% RH showed significantly higher germination (0.36 seedlings/mericarp) than mericarps stored dry, or stored moist for 1-6 or 8-12 weeks. Our findings facilitate development of larger hybrid populations, thus increasing the efficiency of Nolana breeding programs.
J.C. Vlahos and M. Dragassaki
Ebenus cretica, Leguminosae, is a characteristic endemic plant of the Mediterranean island of Crete. It is a perennial bush up to 1 m tall with composite pubescent leaves and pinky red or purple flowers on 5- to 20-cm-long racemes. The fruit is surrounded by the calyx and contains one seed. The plants grow on rocky hillsides in alkaline soils at an altitude of up to 600 m and flower from April to June. Ebenus has the potential for use as a container or landscape flowering plant, and this study was aimed at finding methods to propagate it either by seed or by shoot cuttings. Seed collected from native plants in late July/Aug. 1992 germinated well (70% to 90%) without scarification in a commercial potting mix. Fifty percent of the seed germinated in vitro between 13 and 25 days, depending on temperature and substrate used. Temperatures of 25 or 30C in light at a pH ≈6.0 favored germination. Removal of the dry calyx coating the seed enhanced germination and emergence. For rooting Ebenus cuttings, several concentrations of IAA, IBA, and NAA were used in combination with different types of cuttings (soft or hardwood, tip or basal, cultivated or wild). Best results were obtained by wounding the base and dipping shoot-tip cuttings (12 cm long) in 600 mg IBA/liter for 16 hours. Significant differences, however, were observed among germination and rooting percentages when seeds or cuttings were taken from different plants due to genetic diversity. Therefore, selection is required for optimal results.
Hailin Liu, Cunmeng Qian, Jian Zhou, Xiaoyan Zhang, Qiuyue Ma and Shuxian Li
3, seeds were soaked in concentrated sulfuric acid (98%) with seeds:acid of 1:2 (v/v) for 0, 5, 10, or 20 min (chemical scarification). During treatment, the solutions were stirred continuously with a glass rod. After chemical scarification, the
Guochen K. Png, Katherine S. Downes and Beng H. Tan
removal or scarification of the outer layers of the seed and acid scarification ( Baskin and Baskin, 2004 ). Seeds with non-deep physiological dormancy can also be artificially induced to germinate by seedcoat nicking or more naturally through dry
Larry A. Stein, Jerry M. Parsons and R. Daniel Lineberger
over four times (580 pounds per acre) as much seed per acre as any bluebonnet color ever harvested during the 2010 harvest (John Thomas, personal communication). Cultivation Seeds must be acid-scarified to obtain optimal germination ( Davis et al., 1991
Sean M. Campbell, Brian J. Pearson and S. Christopher Marble
6.8%; although that can be altered to between 5% and 12% with no negative effects, germinability was maximized at 10% seed moisture content. This is often accomplished through scarification or compromise of the seedcoat. Nagar and Meena (2015
Patrick J. Conner
et al., 1981 ). Grape seeds have a thick, tough seedcoat that can be a mechanical barrier to germination. Attempts at scarifying seeds with sulfuric acid provided minimal benefits and was harmful to seed viability if not handled carefully ( ChiaWei
Esther E. McGinnis and Mary H. Meyer
nebraska sedge ( Carex nebrascensis ) and northwest territory sedge ( Carex utriculata ) ( Hoag et al., 2001 ; Jones et al., 2004 ). In other cases, Carex species respond to traditional physical dormancy treatments such as acidic scarification ( Ishikawa
Takahiro Tezuka, Hisa Yokoyama, Hideyuki Tanaka, Shuji Shiozaki and Masayuki Oda
medium supplemented with 3% sucrose and 0.85% agar (pH 5.8) and then incubated at 15 °C in the dark. Seed germination was observed for 10 weeks after incubation. Effect of chemical scarification on seed germination. Ilex latifolia seeds (collected 12 Oct