ISHS Acta Horticulturae 565: VI International Symposium on Temperate Fruit Growing in the Tropics and Subtropics
CHILLING AND HEAT REQUIREMENTS FOR BUDBREAK AND FRUITING OF "ANNA" AND "DORSETT GOLDEN" APPLE CULTIVARS UNDER WARM CLIMATIC CONDITIONS |
| Authors: | S.Z. El-Agamy, A.K.A. Mohamed, F.M.A. Mostafa, A.Y. Abdallah |
| Keywords: | apples, endodormancy, fruit set, fruit development period |
| Abstract:
This study was carried out during 1993/1994, 1994/1995 and 1995/1996 seasons on nine year old Anna and Dorsett Golden apple trees grown under warm climatic conditions of Assiut, Egypt. Chilling requirements were estimated using four methods: total number of hours below 7.2°C, or 10°C; North Carolina and Utah models, from the beginning of endodormancy to maximum budbreak forcing at 20-25 °C. Heat units required to reach various stages of bud development were calculated from budbreak to fruit maturity. Using 10% or 50% budbreak was an unsuitable indicator for endodormancy completion in both apple cultivars. Accumulated heat units (G.D.H.) required to reach full bloom and fruit set were higher in Anna, while bloom to harvest period was longer in Dorsett Golden, and it is recommended as a maturity index in Assiut. | |
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