A green roof system was installed on an existing 35-year-old building. The purpose of the study was to evaluate the effect of three substrate depths on low-temperature injury of six herbaceous perennials: bugleweed (Ajuga reptans), sandwort (Arenaria verna `Aurea'), sea pink (Armeria maritima), whitlow grass (Draba aizoides), creeping baby's breath (Gypsophila repens), and stonecrop (Sedum xhybridum). Plants in 4-inch (9-cm) pots were transplanted into three substrate depths: 2, 4, and 6 inches (5, 10, and 15 cm) and evaluated over a 3-year period. The analysis of the results showed that the species have different winter hardiness, therefore some species were subject to more freezing injury than others. Stonecrop had significantly more damage at 2-inch than 4- or 6-inch depths during the two winters. Bugleweed and creeping baby's breath showed more damage at 2 inches in 1996-97, not in 1995-96. Substrate temperatures were measured from Oct. 1995 to May 1997. Low temperature injury was more pronounced at 2 inch than at 4 or 6 inch depths. Minimum daily temperature and temperature variations measured in fall and spring of these 2 years were also higher at 4- and 6-inch depths.
methodologies will help decide the best course of action and protection strategy before the upcoming freeze. Peach cold hardiness can be measured using the artificial freezing test. The artificial freezing test is commonly accepted as the standard test to
treatment group. Dehardening and Artificial Freezing Test After 8 weeks, seedlings were moved for conditioning into the greenhouse under spring-like growing conditions to initiate the dehardening process. The average daily maximum and minimum
controlled or artificial freezing has also been used to detect cultivar differences in hardiness at specific points in time ( Anderson and Seeley 1977 ; Edgerton 1960 ; Layne 1989 ; Meader et al. 1945 ; Shane 2020 ). Furthermore, other factors can affect
Abstract
Small scale, artificial freezing studies showed that injury was more severe on detached than on attached fruits of ‘Red Spy’, ‘Delicious’, and ‘Idared’ apples.
artificial/cold room and low/above freezing versus subzero freezing temperatures) indicates that there are major differences in gene expression under the different environments, and the differences may be genotype-dependent. To draw meaningful conclusions
Abstract
Studies show electrical potential (Millivoltage output) generated by citrus seedlings is useful as an indication of freezing in hardened seedlings or where freeze rates are 1° hr-1 or less. Needle-sharp probes of a gold-amalgam wire attached to a strip chart recorder with a variable millivolt supply were used to detect mv changes in seedlings exposed to freeze conditions in an artificial environment room. An abrupt increase of 2 to 6 mv in the mv signal indicated the onset of freezing in the seedlings as checked by the heat of crystallization measured with thermocouples, visual signs of freezing, and subsequent physical damage studies.
Abstract
Dormant twigs of a number of Ericoideae (genera Erica and Calluna) species were collected in midwinter at Gotemba, Shizuoka Prefecture. These twigs were artificially hardened at the temperature from −1 to −3°C for 15 days to increase hardiness and then subjected to controlled test temperatures to assess their hardiness. European ericas were observed to be much hardier than those from South Africa, resisting freezing from −15 to −20°C. South African ericas were hardy only from −5 to −8°C. Calluna cultivars survived freezing down to −30°C.
Abstract
Freezing resistance of winter twigs from about 300 tree species and cultivars native to different climates in the world was assessed. Dormant 1-year-old twigs collected from mature trees were artificially hardened. Almost all of the trees, which ranged from tropical to subtropical in both Asia and America, sustained freezing injury to some of their tissues at temperatures below −5°C. Evergreen and deciduous broad-leaved trees native to warm-temperate climates survived freezing at −7° to −20°. In general, flower buds were far less resistant than vegetative buds. Winter minimum temperature is among the important factors governing the northern limits of cultivated plants.
Abstract
High temperature prior to controlled freezing increased inner bark and xylem injury in twigs of both ‘Siberian C’ and ‘Redhaven’ peaches (Prunus persica (L) Batsch). ‘Siberian C had a lower natural moisture content than ‘Redhaven’. Artificially increasing moisture content did not affect xylem injury, but increased inner bark injury. Significant temperature by cultivar and moisture by cultivar interactions were found with inner bark. We concluded that the superior hardiness of ‘Siberian C’ was not due solely to its lower moisture content.