S. DOBREVA, T. SLAVTCHEVA and A. DONCHEV
Institute of Viticulture and Enology, BG-5800 Pleven, Bulgaria
DOBREVA S., T. SLAVTCHEVA and A. DONCHEV, 2006. Vine resistance to low winter temperatures and its relation to the main agrobiological and physiological characteristics. Ill Resistance and recovery from frost damages. Bulg. J. Agric. Sci., 12: 393-404
The study held with cvs. Merlot, Bouket, Cabernet Sauvignon and Rkatziteli aimed to establish comparatively the low winter temperature resistance and its relation to the main agrobiological and physiological characteristics. The cold hardiness was determined after freezing tests or cold damages in the vineyard. Comparisons were made between cold hardiness and some other characteristics established during vegetation period or dormancy (bud fertility, grape yield, leaf area, annual growth, leaf pigments, carbonydrates in ripening shoots, dark respiration of shoots during autumn-winter period etc ). The variety specific response to the cold injury was discussed in this final article of the series, as well.
Cv. Bouket showed the highest resistance to low winter temperatures, followed by cvs. Cabernet Sauvignon and Rkatziteli; the lowest one was established with cv. Merlot. However, some differences were found between the frost-hardy varieties Bouket and Cabernet Sauvignon on the one hand and low-resistant Merlot on the other hand. The grapevines of Merlot had better vegetative and reproductive ability (higher fertility and grape yield, greater number of leaves and leaf size, more leaf pigments, more sugars in the autumnal leaves, higher starch and water contents in the ripening shoots, intensive shoot dark respiration during dormancy etc). It was found that the rate of leaf pigment decrease during vegetation period corresponded to frost hardiness of the varieties studied. Cv. Bouket indicated the greatest ability of recovery from frost damages. Regardless of Cabernet Sauvignon better cold hardiness, its grape yield decreased more, compared to Merlot, because of higher reduction of fruitful shoots. The varieties differed among themselves by their recovery ability for vegetative growth.