Histological and Physiological Studies on Flowering and Fruiting of Some Peach Cultivars Under Assiut Environment

摘要

THE PRESENT STUDY was carried out during 1997/1998 and 1998/1999 seasons on the peach cvs. (San Pedro, Y9/106 and Rubidoux, as early, mid- and late maturing, respectively grown under Assiut climatic conditions. Histological studies revealed that twelve stages could be detected through the generative process from mid of June up to end Feb or early March. The preliminary stages of floral bud occurred approximately at the same time in the three studies cvs. but the late stages (primordia of ovules) wereformed during Jan 26, Feb. 9 and March 9 for the three cvs. respectively. Chilling units according to total hours ≤ 7.2°C were 275, 294 and 323 for San Pedro, Y9/106 and Rubidoux peach cvs, respectively from Dec. till bud swelling at the field. Theseunits were (632, 697 & 837) and (187, 177 & 62) according to total hours ≤ 10°C and Utah model, respectively. Concerning heat units for bud break till fruit maturity, it was found that accumulated heat units (GDH) required to budburst, full bloom, fruit set and fruit maturity were higher in Rubidoux cv. than in both San Pedro and Y9/106 cvs. It could be recommended that more care should be given to peach tree during floral bud differentiation, normally upon harvesting; such care would affect the yield of next year and using heat units calculation as an index for peach fruit maturity. Late cultivar (Rubidoux) is not recommended under Assiut climatic conditions.