General Characteristics of Bud Dormancy in the Vine

Evaluation of Chilling and Heat Requirements for the Budbreak of Delaware Grape in Osaka, Japan

“…The chilling periods identified by PLS regression occurred around mid-September or mid-October to early February, which is consistent with the previously mentioned dormancy processes (Horiuchi et al 1981). Notably, in all three chilling models, some periods with positive model coefficients or low VIP scores occurred during the chilling periods, which is consistent with the results of several studies (Luedeling 2013a, Guo et al 2015, Martínez-Lüscher et al 2017.…”

“…Controlled experiments using detached twigs revealed that the endodormancy of Delaware in Osaka was induced primarily by low temperatures (10 to 18°C) (Tohbe et al 1998) and was in its deepest phase from late September to late October. Thereafter, endodormancy breaking began, and transitioned to ecodormancy during late January to early February (Horiuchi et al 1981). According to the PLS results and the previous experimental works (Horiuchi et al 1981, Tohbe et al 1998, the high temperatures in September and October appear to delay budbreak by inhibiting dormancy induction and breaking.…”

“…Thereafter, endodormancy breaking began, and transitioned to ecodormancy during late January to early February (Horiuchi et al 1981). According to the PLS results and the previous experimental works (Horiuchi et al 1981, Tohbe et al 1998, the high temperatures in September and October appear to delay budbreak by inhibiting dormancy induction and breaking. Conversely, high temperatures from 10 Nov had the effect of advancing budbreak, suggesting that the buds were responsive to heat at that time.…”

“…Conversely, high temperatures from 10 Nov had the effect of advancing budbreak, suggesting that the buds were responsive to heat at that time. Grapevines have the capability to fulfill their critical chilling requirements earlier than most woody perennial species (Horiuchi et al 1981, Mullins et al 1992, Martínez-Lüscher et al 2016. However, the VIP values and negative coefficients for November to December were considerably lower than those for the subsequent periods, suggesting that the budbreak-advancing effect was weak in most years.…”