as a commercial ornamental plant in North America is limited, principally because of a lack of cold hardiness. Almost all of Australia corresponds to the U.S. Department of Agriculture (USDA) hardiness zone 9 or higher ( Dawson, 1991 ), and as a
physiological responses of the plants to cool winter temperatures, not necessarily their specific cold hardiness. Various studies have demonstrated changes in chlorophyll content ( Nunez-Olivera et al., 1994 ), pigments and antioxidants ( Garcia-Plazaola et al
. Cane samples were collected from the field trial site on the day of analysis. Data for phenology, yield, berry composition, cold injury ratings, and cold hardiness were analyzed using a linear mixed model analysis of variance (SAS version 8.02; SAS
, particularly when irrigated; this size is impractical for some landscapes and gardens. Little specific information on the cold hardiness of species of ceanothus cultivars is available. An estimation of winter hardiness can be inferred from the native range of
into cold storage; (1.8 × °C) + 32 = °F. Cuttings were taken from each tree on days 0, 3, 7, 14, and 20 for the cold hardiness study. On each day, 11 cuttings ≈2 to 3 inches in length were taken from each tree. The cuttings were divided into one control
thought ( Dirr, 2009 ). Cold-hardiness of the hybrid fortune’s osmanthus appears to be intermediate to that of its parents ( Dirr, 2009 ), indicating that hybrid breeding may be a promising avenue for improving cold-hardiness in the genus. Germplasm
found throughout the upper midwestern United States. Some grasses have the ability to survive in U.S. Department of Agriculture (USDA) climate zones lower than the zone in which they are listed and some should be reevaluated for cold hardiness. Silver
The capacity of plant materials to resume normal growth after exposure to low temperature is the ultimate criterion of cold hardiness. We therefore determined the low-temperature tolerance of five commercially important herbaceous perennial species. Container-grown blanket flower (Gaillardia ×grandiflora Van Houtte. `Goblin'), false dragonhead [Physoste- gia virginiana (L.) Benth. `Summer Snow'], perennial salvia (Salvia ×superba Stapf. `Stratford Blue'), painted daisy (Tanacetum coccineum Willd. `Robinson's Mix'), and creeping veronica (Veronica repens Loisel.) were subjected to 0, -2, 4, -6, -8, -10, -12, -14, -16, and -18C in a programmable freezer. The percentage of survival of most species was adequate when exposed to -10C. Producers of container-grown perennials are advised to provide winter protection measures that prohibit root medium temperatures from falling below -10C.
Our objectives were to determine if gibberellic acid (GA3) application at color break in the fall affected the juice content, soluble solids content (SSC), titratable acid (TA), and ratio of SSC: TA of `Hamlin' orange (Citrus sinensis) fruit following moderate to severe freezes. We also wanted to know if GA3 affected the post-freeze rate of decrease in juice content, fruit and tree cold hardiness, and the amount of fruit drop following a freeze. GA3 (18 floz/acre) was applied at color break in the fall of 2002, 2003, and 2004 to `Hamlin' orange trees on Swingle citrumelo (C. sinensis × Poncirus trifoliata) rootstock planted in 1995 at Gainesville, Fla. Moderate to severe freezes occurred in all three seasons. Fruit were harvested at about 2-week intervals following freezes in each season and the internal fruit quality was determined. GA3-treated fruit generally had higher juice content compared with nontreated fruit for 8 weeks after moderate to severe freezes in all three seasons, which may be economically important to citrus processors and growers since Florida growers are paid based on fruit pounds-solids (juice content × SSC). The rate of decrease in juice content over time was similar for both treatments in seasons one and two, but was less for GA3-treated fruit than nontreated fruit in season three. In addition, SSC was equal to or slightly greater for fruit treated with GA3 than for nontreated fruit. Fruit drop rate and magnitude were also significantly less for the GA-treated compared with nontreated trees in two of three seasons. GA3 did not affect fruit, leaf, or tree cold hardiness in any season.
). However, cold hardiness is a characteristic that is not as easily tested as productivity; therefore, some released cultivars have unknown cold hardiness, posing a risk for cold-climate growers. Different kinds of artificial freezing test methods have been