Effect of Late-Season Defoliation on Vine Cold Tolerance and Chilling Requirement: An Introduction to Greenhouse Grape Production
Pages 1-11
https://doi.org/10.22034/jgpp.2026.741586
Ehsan Totoonchi, Hassan Sarikhani, Majid Rostami, Mohammad Abdoli, Rouhollah Karimi
Abstract The late-season source leaves play a decisive role in the grapevine's cold tolerance and chilling requirements. The objective was to evaluate the effect of manual late-season defoliation on the cold tolerance and chilling requirements of ‘Bidaneh-Sefid’ grapes. Treatments were applied on October 23 via manual leaf removal of the canes at four levels: 1) control (no leaf removal), 2) apical-node defoliation, 3) Basal-node defoliation, and 4) All-node defoliation of the canes. Based on the results, the lowest cold tolerance (highest electrolyte leakage, or EL) as assessed via the EL method was observed in the ‘all-node defoliation’ treatment, whereas the highest cold tolerance (lowest EL) was found in the control vines. The highest levels of glucose, fructose, sucrose, and raffinose were recorded in the control treatment, while the lowest levels of these soluble sugars were observed in the ‘all-node defoliation’ treatment. Similarly, the highest levels of putrescine, spermidine, and spermine were found in the control treatment. Abscisic acid content in the vines subjected to ‘all-node defoliation’ treatment was 28.5% lower than that of the control vines. The highest levels of gibberellin and auxin were observed in the control plants. In the defoliation treatments group, budbreak (time to 50% budburst) occurred 11 days earlier than in the control group. ‘All- node defoliation’ delayed the rate of budbreak. Overall, it was determined that late-season defoliation can reduce cold tolerance in vineyard vines, however, this horticultural practice can be employed to accelerate budbreak following a standard 400-hour chilling treatment for greenhouse grape production.


This journal is licensed under a 