traditional crops, including grapes. There are predictions for dramatic reductions in suitable wine grape acreage in the United States—up to 81% by the late 21st century ( White et al. 2006 ). Grape seeds have physiological dormancy and usually require 3 to
( Holzmueller et al., 2007 ; Thomas, 1969 ). Typically, C. florida is propagated from seeds, but the seeds usually develop strong dormancy ( Coartney et al., 1989 ), which may be a great challenge for seed reproduction ( Dirr and Heuser, 1987 ). Studied with
Stoddart, 1980 ). Additionally, ABA has been suggested as a dormancy-inducing hormone because it accumulates in dormant nodes and increases after the tissue is exposed to low temperatures ( Dogramaci et al., 2010 ). The variation of ABA concentration in
The evergreen (EVG) peach, first described in Mexico, was used as a parent with deciduous (DE) peaches to develop F1 and F2 hybrid populations in Mexico, Florida, Georgia, and West Virginia. F1 trees were DE and F2 plants segregated 3 DE: 1 EVG. In West Virginia, the most temperate location, the heterozygous class could be distinguished in the first few years of growth by late leaf abscission in the fall. Segregation ratios suggest that the EVG trait is controlled by a single gene, evg, the EVG state being homozygous recessive. Evergreen trees were characterized by insensitivity of shoot tips to daylength and failure of terminal growth to cease growth until killed by low temperature. Lateral buds of EVG trees went dormant in the fall. Deep supercooling occurred in both EVG and DE trees, but it appeared later in EVG trees, was of shorter duration, and occurred to a lesser extent. Evergreen germplasm may be useful in developing peach cultivars for frost-free subtropic and tropical areas. It also presents a useful system for studying dormancy and cold hardiness.
Winter survival of temperate fruit tree crops is the phase of inhibited growth known as dormancy ( Faust et al., 1997 ), controlled by mechanisms occurring in the possibly affected parts of the tree ( Campoy et al., 2011 ). To date, the
capable of developing into flowering shoots. Flowering shoots of gentian develop from the overwintering crown buds produced in the previous growing season. Crown buds are dormant in winter until growth recommences in spring when they emerge, with floral
Potted plants of red-osier dogwood (Cornus sericea L., syn. C. stolonifera Michx) were grown under 3 different dormancy-inducing regimes. Each week 5 plants per group were defoliated and placed in a warm greenhouse. Plants were checked daily for regrowth and new leaves were removed. When defoliation ceased to induce bud break, the plants were considered to be in a state of winter dormancy. Plants were observed for damage the following spring to determine when they had reached vegetative maturity, and it was found that vegetative maturity corresponded to winter dormancy development in all 3 growing conditions.
158 WORKSHOP 24 Quantification of Plant Dormancy
Effects of methyl disulfide (MeS2) on sprouting and phytohormones in dormant corms of spring-flowering gladiolus (Gladiolu×Tubergenii Hort. `Charm') were studied. Corms treated with MeS2 sprouted 30 days earlier than nontreated corms. The concentrations of endogenous promoters in the corm tissue increased and inhibitors decreased within 24 h of treatments. High concentration of inhibitors were present in the nontreated corms.
Inner scales excised from dormant bulbs of the short-day `Texas Grano 1015Y' onion (Allium cepa L.) were cultured in vitro and leaf growth was examined. Light promoted leaf growth, but no differences in leaf growth were observed for media pH between 4 and 7. Leaf growth rate in darkness was highest at 24C, reduced at 15C, and greatly reduced at SC. Kinetin promoted leaf growth at 1, 10, and 100 μm. IAA was effective at 1 and 10 μM, but not at 0.1 and 100 μm. GA3 promoted growth at 0.1 μM. No inhibitory effects of ABA on leaf growth could be detected. Chemical names used: 1-H-indole-3-acetic acid (IAA), abscisic acid (ABA), gibberellic acid (GA3), 6-furfurylaminopurine (Kinetin).