Performance of the new seedless grape ‘BRS Isis' grown in subtropical area

‘BRS Isis' is a new colored seedless table grape tolerant to downy mildew, the main vine disease in subtropical humid areas. This new seedless cultivar is an interspecific hybrid from the crossing of CNPUV 681–29 [Arkansas 1976 X CNPUV 147–3 (‘Niagara Branca' x ‘Venus')] x ‘BRS Linda', and was recently released by Embrapa Grape and Wine, Brazil. The performance of ‘BRS Isis' seedless grape was evaluated in an experimental vineyard in 2016 located in a subtropical area at Marialva city, state of Parana, Brazil. The vines were grafted onto ‘IAC 766 Campinas' rootstock and trained in an overhead trellising system spaced at 2× 5 m. Vines were cane-pruning in late winter of July 2016, and for assessments, 20 representative vines were selected in the area. As ‘BRS Isis' is a very fruitful grape, presenting 4 bunches per shoot, a load adjustment was performed after fruitset removing 50% of bunches per shoot, leaving 2 bunches per shoot, equivalent to a density of 10 bunches.m−2. The duration in days of the main phenological stages from pruning to harvest, and the physicochemical and yield characteristics of ‘BRS Isis' seedless grape were subjected to evaluation. It was determined that the cycle is 144 days. The means of berry and bunch weight was 6.7 ± 1.0 g and 500.0 ± 0.04 g, respectively, and the color index of berries (CIRG) was 4.3 ± 1.3. The means of total soluble solids (TSS), titratable acidity (TA) and maturity index (TSS/TA) observed were 14.2 ± 0.3° Brix, 0.6 ± 0.04% of tartaric acid and 24.1 ± 1.5, respectively, while the yield was 49.0 ± 5.7 tons.ha−1. The yield observed is considered high to keep a sustainable crop over time, thus, in order to obtain grapes of ‘BRS Isis' with regular yield, and possibly, with a higher content of soluble solids, it is desirable to keep only 1 bunch per shoot (5 bunches.m−2) after fruitset.