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  • Author or Editor: Frank G. Dennis x
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Abstract

The National Peach Council sponsored a workshop for scientists working on dormancy and hardiness of peach and other fruit trees on March 2, 1977 during its National Convention. The purpose of the workshop was to exchange ideas and to develop new ones with the aim of developing better techniques for preventing winter and spring freeze injury.

The workshop, attended mainly by participants from the Eastern U.S., included sessions on breaking and/or prolonging dormancy, environmental and cultural control of hardiness, freeze control systems, and natural control of hardiness. The following is a brief report on material covered. A more detailed report and a list of participants may be obtained upon request.

Open Access

Abstract

Explaining the physiological basis of rest or endodormancy (23) in seeds and buds has been the goal of considerable research effort within the past 40 years. One of the most popular approaches has been to study hormonal control, based on the hypothesis that growth-inhibiting compounds accumulate in buds and seeds as growth slows or seeds mature, and that these are metabolized, or that growth promoters are synthesized, or both, during subsequent exposure to rest-breaking treatments (moist chilling, dry after-ripening, exposure to light, etc.)

Open Access

Abstract

• In the article “Two Methods of Studying Rest: Temperature Alteration and Genetic Analysis”, by Frank G. Dennis, Jr.(HortScience 22(5):820–823, October 1987), Table 1 was printed incorrectly. The corrected table appears below.

Open Access

Abstract

We were unable to confirm the observations made by others that ethylene (C2H4) is required for germination of stratified embryos of apple (Malus domestica Borkh.) In addition, silver thiosulfate and norbornadiene (1000 µl·liter-1), which in-hibit C2H4 action, either slightly promoted or did not affect seed or embryo germination. The addition of 166 or 332 µl C2H4/liter significantly inhibited rate and final percentage of germination of fully stratified seeds. Removal of atmospheric C2H4 or addition of C2H4 (up to 332 µl·liter-1) did not reduce the inhibitory effect of high temperature (30C) on seed or embryo germination. We conclude that the presence of atmospheric C2H4 at concentrations >20 nl·liter-1 is not essential for germination of apple seeds or embryos.

Open Access

Some apple cultivars are biennial. Experiments with the facultatively parthenocarpic apple cultivar `Spencer Seedless' indicated that seeds are responsible for inhibiting flowering (Chan and Cain, Proc. ASHS 91:63-68, 1967). Because gibberellin inhibits flowering in apple, seed GAs may be responsible for biennial bearing, or seeds may affect metabolism of GAs in bourse shoots. To obtain additional information, 14C - G A12 was injected into seeds or bourse shoots of `Spencer Seedless' and the metabolites were extracted after 24 or 48 hr. Metabolites moved from seeds to bourse shoots and vice versa in 1992, only the most polar compound(s) being transported. However, transport was not observed in 1993. Five metabolites of 14C - G A12 were found in apices following injection, 5 to 7 in seeds. Two metabolites occurred in fruit flesh following seed treatment. The presence of seeds appeared to have no qualitative effect on metabolism in the bourse shoot, although the metabolites have not yet been identified.

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