Effect of last irrigation time and harvest date on some physiological characteristics and cold hardiness in grapevine buds

The 'Khzandeh' system is one of the traditional systems for grape training in Iran. In this system, the roots of the plants are laid down in a trough (depth: 80 cm and width: 100 cm), and the trunk is placed on a small mound formed after digging the streams. The amount of water used in this system is considerable, and the time of the last irrigation and harvesting in this method is more important than for other systems. This training system is widely used in many parts of Iran such as 'Shazand', 'Khondab' and 'Malayer' and some years, the vineyards occasionally suffer from severe frost damage in autumn, winter and early spring. The objective of this research was to evaluate the effect of the time of the last irrigation and of the last harvest date on physiological and fruit quality parameters and cold hardiness of grapevine buds ('BidaneSefid' cultivar). This experiment was performed in a randomized complete block design (RCBD) for two years (2015-2016). Treatments consisted of three different dates for final irrigation (from 23rd August to 29th September). Harvesting was carried out 10-12 days after final irrigation. Results showed that delaying the time of the last irrigation and of the last harvest in the fall improved bud cold tolerance as well as fruit quality. In general, early interruption of irrigation and earlier harvest reduced the percentage of total soluble solids on the one hand and increased acidity and electrolyte leakage on the other hand. It can thus be concluded that early interruption of irrigation and harvesting when the fruit quality parameters are not optimal will lead to increased electrolyte leakage in artificial cold conditions. In other words, when the percentage of soluble solids and the pH are lower than 26 and 3, respectively, the possibility of damage increases in grape buds. According to the results of this two-year experiment, harvesting with a delay not only increases the quality of fruit, but also increases the vine tolerance against winter freezing and chilling. While the process of drying raisins in Iran is performed outdoors, it is important to determine the best harvest time to avoid autumn rainfall during this process. For this reason, it is recommended that we adjust the suitable irrigation cycle and fertilization to promote fruit ripening as well as fruit quality in grapes, because farmers do not dry their raisins indoors.

Hassan Hoseinabadi won an ISHS Young Minds award for the best poster at the I International Conference & X National Horticultural Science Congress of Iran (IrHC2017) in Iran in September 2017.

Hassan Hoseinabadi, Institute of Grapes and Raisins, Malayer University, Malayer, Iran, e-mail: hoseinabadi.1156@gmail.com

The full article is available in Chronica Horticulturae