Phenology and berry development of deficit irrigated 'Cabernet Sauvignon'

International audience

Inglés. Irrigation supply is an essential factor of grapevine production in many regions. This study aimed to analyse its effects on vine phenology, reproductive development and fruit composition of Vitis vinifera 'Cabernet Sauvignon', and to provide a basis for simulating berry growth from berry set to harvest (H). Experiments were conducted over two seasons in a commercial vineyard in Victoria, Australia. Irrigation treatments in 2004-2005 consisted of a standard irrigation (S), a regulated deficit irrigation (RDI) with a two-week period of reduced irrigation compared to S from flowering (F) to veraison (V), and a prolonged deficit irrigation (PD) with a two-week period of reduced irrigation followed by a two-week period of no irrigation from F to V. Treatments S, RDI and PD received 387, 370 and 314 mm irrigation, respectively, from budburst (B) to H. In 2005-2006, only the PD treatment was retained, with a four-week period of no irrigation from F to V. It received 326 mm from B to H. A fully-irrigated control treatment (C) was imposed on the S plots receiving 931 mm from B to H. In 2004-2005, the period B-F was slightly less for RDI than PD, but similar for S compared to RDI and PD. Inflorescence dry weights (DW) of S and RDI were higher than PD. Berry volume and DW at H of RDI were similar to S and PD, but higher for S than PD. In 20052006, C had a lower ratio of seed to berry DW and a higher ratio of flesh to berry DW than PD. Its titratable acidity was higher than PD and its anthocyanin and total phenolics concentrations were lower. Deficit irrigation (PD) reduced berry fresh weight (FW) accumulation from set to the onset of V (V10: 10% veraison) (20042005), and from V10 to H (2004-2006), mainly due to a decrease in berry DW accumulation. Berry water content (WC, % of berry FW) was similar among the treatments, except from V10 to H (2004-2005), with higher WC for PD than RDI. Berry DW accumulation was linearly linked to thermal time during the periods set-V10 and V10-19 degrees Brix for all irrigation treatments. Curves slowed after this stage. Such results form a basis for development of berry weight modelling routines.