The phenological behaviour and heat summation requirements of seedless grapes were studied in the San Francisco River Valley during the seasons 2001-2002, for six pruning dates (12/2000, 04/2001, 06/2001, 10/2001, 01 and 02/2002 and 04/2002). The varieties evaluated were Superior Seedless (Festival), Thompson Seedless, Catalunha, Perlette and Marroo Seedless, grafted on IAC 572 (' Jales'). The number of days were evaluated for the following phenological phases: bud dorment to bud swelling (1), bud swelling to bud breaking (2), bud breaking to five to six leaves unfolded (3), five to six leaves unfolded to beginning of flowering (4), beginning of flowering to ending of flowering (5), ending of flowering to fruit set (pellet-like berries) (6), fruit set to the pea-size berries (7), pea-size berries to beginning of bunch touch (8), beginning of bunch touch to beginning of ripenning (9) and beginning of ripenning to berries ripe (10). Heat summation requirements were observed in degree-days (DG) necessary to start each phenological phase from the pruning date until the harvest. The average phenological cycle varied of 89 days and 1315 DG in the Superior Seedless to 105 days and 1514 DG in the Perlette. The periods among the beginning and ending of the maturation, beginning of bunch touch to beginning of maturation and 4 to 6 leaves separated to beginning of flowering presented the largest duration among all the subperíodos in all varieties.
phenology; seedless grape; heat requirements
