Phenology and thermal demand of 'Isabel' and 'Rubea' grapevines on different rootstocks in North of Parana

The aim of this research was to characterize the phenological behavior, as well as to determine the thermal demand of 'Isabel' (Vitis labrusca) and 'Rubea' (V. labrusca x (V. labrusca x V. vinifera) x V. labrusca) grapevines for grape juices in the North of Parana. The trial was carried out in a experimental vineyard located at Technology Center of Corol Cooperative, located at Rolandia, PR. The vineyard was established in July, 2002 and grafted in 2003. The design was used as the statistical model with four replications in a factorial 20 project (2 grapevines and 3 rootstocks). The plants were cultivated in GDC (Geneva Double Curtain) system, in 2.0 x 3.5 m spacing. To evaluate the duration of each phenological stage (in days) four spurs were marked per plot, where was evaluated in days until the bud swell, to beginning of shot growth, to visible cluser, to flowering; to early ripening and to harvest. The thermal demand was calculated using the degree-days sum from pruning to harvest, as well for each subperiod. The results show that the duration of the pruning to harvest for grape 'Isabel' grafted on rootstocks IAC 766 Campinas, IAC 572 Jales and 420-A was 148, 142 and 167 days, respectively and the thermal demand to this combination was 1,260.9; 1,260.9 and 1,541.6 GD, respectively. For 'Rubea' grafted on rootstocks IAC 766 Campinas, IAC 572 Jales and 420-A the cycle was 134,134 and 132 days, respectively and the thermal demand from pruning to harvest for even combinations was 1,003.8; 1,003.8 and 999.5 GD, respectively.