Phenology and thermal summation (degree days) for 'Isabel' grape (Vitis labrusca) produced in the Northwest of Parana State

Abstract

The objetive of this research was to characterize the phenological performance of 'Isabel' grape (Vitis labrusca) produced in the northwest of Parana state, as well to characterize its thermal demand in degree-days. The experimental area was established in a commercial vineyard of Vinícola Intervin®, Maringá, PR. The vineyard was planted in August of 2000 and the trees were trained in a pergola system, in a 4.0 x 1.0 m spacing. The evaluations started from the winter pruning of 2003. The random design was used as the statistical model with 20 replications and each plot was composed by one tree. The phenology of grapes was evaluated considering the duration in days of each one of the following subperiods: pruning to bud swell, pruning to beggining of shoot growth, pruning to visible cluster, pruning to flowering, pruning to early ripening and pruning to harvest. The thermal demand of 'Isabel' grape was determined using the degree-days summation from the pruning to harvest, as well for each of the subperiods, considering two base-temperatures (10oC and 12oC). It was possible to conclude that: the duration of the 'Isabel' grape (pruning to harvest) in the northwest of Parana is 127 days, and its thermal demand is 1,238.20 degree-days. The most suitable base-temperature to calculate this demand was 10oC.