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study were: 1) to determine cold hardiness of seven commercial Iranian pomegranate cultivars in different stages of the hardening cycle, from fall through winter; and 2) to study changes in carbohydrates and proline contents during acclimation and
Cold hardiness levels of six cultivars of Chinese elm (Ulmus parvifolia Jacq.), `Select 380', `Orange Ribbon 740', `Emerald Isle', `Emerald Vase', `Drake', and `King's Choice', were determined over eight sample dates from 31 Aug. 1988 to 16 May 1989 and for `Emerald Vase' and `Drake', over three dates from 14 Feb. 1988 to 25 Apr. 1988. All cultivars tested achieved a maximum cold hardiness in December and January of – 21 to – 24C, except `King's Choice', which survived exposure to at least – 30C. `Emerald Isle' and `Emerald Vase' acclimated earlier (both – 9C on 31 Aug.) and reacclimated later (– 6 and – 9C, respectively, on 16 May) than other cultivars tested. `Emerald Vase' and `Drake' exhibited similar cold hardiness levels over the two years tested.
composition with minimal decrease in midwinter primary bud cold hardiness ( O’Daniel et al., 2012 ). However, pruning is a rough regulator of yield and does not adequately control crop level or cropload of interspecific hybrids ( Howell et al., 1987 ; Kaps
Abstract
More than 4500 accessions of eight genera including Pyrus at the National Clonal Germplasm Repository, Corvallis, Ore., require testing for cold hardiness. Since pear xylem deep supercools (7), differential thermal analysis (DTA) would be a suitable test if large numbers of samples could be examined simultaneously. The object of this study was to produce a method of multichannel DTA for defining cold hardiness of pear accessions. Visual browning was also examined to confirm cold hardiness values.
cold tolerance of S. americanus . Therefore, we investigated midwinter-hardiness and deacclimation patterns of populations of S. americanus from northern and southern locations within its natural distribution. Cold acclimation is the accrual of cold-hardiness
, and high fruit quality ( Galletta and Ballington, 1996 ). Cold hardiness is the result of complex physiological mechanisms involving many cellular and whole plant details. Moreover, winterhardiness is affected not only by tolerance to cold but also by
Cold hardiness is the ability of a plant or plant organ to tolerate freezing or survive freezing conditions ( Fuchigami, 1996 ) without sustaining injury ( Lindén et al., 2002 ; Weiser, 1970 ), which is a major determinant of plant species growth
Two species of Passiflora, P. edulis f. edulis (purple passion fruit) and P. edulis f. flavicarpa (yellow passion fruit), and P. incarnata (maypop), were evaluated for acclimation and cold hardiness, using differential thermal analysis, electrolyte leakage and the tetrazolium stain test. The two species showed the capacity to acclimate several degrees during the evaluation period and the three tests gave similar lethal temperatures for the two species; –9C to –10C for yellow passion fruit, –10C to –12C for purple passion fruit and –11C to –13C for maypop. Purple and yellow passion fruit were also assayed for survival after a freeze-thaw cycle, using a tissue culture regeneration technique called “feeder plate”. Yellow passion fruit did not show the capacity to regenerate at any of the temperatures used (0, –3, –6C). Purple passion fruit showed callus formation even at the lowest temperature (–6C).
Stem and bud tissues of promocanes from more than 260 Rubus genotypes were evaluated for mid-winter cold hardiness after laboratory freezing in January 1990. T50 values were calculated for cane samples of red, yellow, black and purple raspberry, and blackberry cultivars, hybrids and species. Red raspberries exhibited the hardiest stem tissue, although several purple raspberries (Rubus sp. cvs. Brandywine, Royalty) survived as low as -33 C. Fall fruiting red raspberries, such as R. idaeus L. cvs. Zeva Remontante, Indian Summer, St. Regis, and Fallred, survived from -23 to -25 C. Summer-bearing cultivars, Canby and Puyallup, survived to -30 C. Stems of several black raspberries (R. occidentalis L. cvs. New Logan, Bristol) survived to -27 C. Stems of the hardiest blackberry cultivars, (R. sp. cvs. Black Satin, Smoothstem) survived to -22 C. In most genotypes the region of the bud at the axis of the stem was less hardy than tissues within the bud scales. Buds tissue was 2 to 10 C less hardy than stem tissue. Field plants were also visually rated for cold injury following record low temperatures occurring in 1989, 1990, and 1991.
damage and yield losses when the most vulnerable tissue, floral buds, deacclimate (loss of cold hardiness). Peach plants deacclimate and become susceptible to freezing temperatures at the end of February, but spring freeze risk remains until late March