Crop load and harvest date have minimal impact on bud cold hardiness and cane carbohydrate levels of four grapevine cultivars

Abstract

Four grapevine cultivars ('Pinot gris', 'Riesling', 'Cabernet franc', 'Cabernet Sauvignon') were subjected to six different field treatments in 2011 [two crop loads (full, half) X three harvest dates [normal (T0), 3 weeks after T0, 6 weeks after T0] in a randomized block design with a factorialized treatment arrangement. All treatments were sampled four times over the 2012 dormant season from January to March. Bud cold hardiness was evaluated for all four cultivars by measuring low temperature exotherms (LTEs) of dormant buds using differential thermal analysis. Cane carbohydrates (CHOs) were likewise analyzed in 'Pinot gris' and 'Riesling'. CHO analysis was done using an 80 % ethanol extraction and HPLC. Neither CHO levels nor cold hardiness were substantially affected by either crop level or harvest date. Consistent patterns of CHO changes and LTE values in each cultivar indicated that deacclimation was unaffected by treatment. Cold hardiness may be influenced more by cultivar specificity based on rates of maturation than by treatment.