Identification and comprehensive evaluation of cold resistance of wine grape germplasms in Northern Tianshan Region, Xinjiang

【Objective】Xinjiang is the largest grape-producing area in China. The main species cultivated there is Vitis vinifera. The buried vine cold-proof cultivation technology is used to ensure safety of overwintering, which would cause destruction of soil surface and consume labor. The study aimed to evaluate the cold resistance of wine grape germplasms in Xinjiang and screen out some cold resistant germplasms for breeding new varieties.【Methods】34 accessions of V. amurensis × V. vinifera and 41 accessions of locally planted germplasm were used for the study. The mature annual branches were subjected to low-temperature stress treatments at -10, -15, -20, -25, -30, and -35 ℃, respectively, and 4 ℃ was taken as the control. The relative conductivity (REC), peroxidase (POD) activity, proline (Pro) content, soluble sugar (SS) content, and malondialdehyde (MDA) content were measured, and the half-lethal temperature (LT50) was calculated by combining with the logistic equation. A comprehensive evaluation of cold resistance was carried out using the affiliation function method, and 75 test materials were graded by cluster analysis, and their physiological and biochemical indexes were comparatively analysed.【Results】The branch conductivity of the 75 germplasms conformed to the typical“S”- shaped curve, and the fit of the logistic equation for each variety (line) was R2 between 0.764 and 0.996, with the LT50 ranging from -8.550 to -29.153 ℃, and the LT50 of the V. amurensis × V. vinifera and V. vinifera ranging from -15.935 to -29.153 ℃ and -8.550 to -21.003 ℃, respectively; the values of the affiliation function ranged from 0.061 to 0.986 for 75 wine grape germplasms, among them, Beimei, Beihong, Beibinghong, Zuoyouhong, 11-5-36, 11-14-45, 12-3-23, 12-5-6, 12-10-60 and 12-16-95 had a combined rating between 0.8 and 1.0 with high cold resistance; Marselan, Cabernet Sauvignon and 12- 16- 96 had a combined rating of 0.056, 0.552 and 0.563, respectively, with moderate cold tolerance; Carignan, Cabernet Franc, Baigendi, Sauvignon Blanc, Neuburgske, Jiubai, and Ruby Cabernet had a combined rating between 0.0 and 0.2 with poor resistant to cold. The results differed somewhat from the results of the unifactorial evaluation using LT50 as an indicator, but the overall ordering was similar. The cluster analysis graded 75 wine grape germplasm into highly cold-tolerant (Ⅰ), cold-tolerant (Ⅱ), moderately cold-tolerant (Ⅲ), and low-temperature-sensitive germplasm (Ⅳ), of which the grade Ⅰ included 11 germplasm, all of them were the accessions of V. amurensis × V. vinifera and highly cold-tolerant germplasm; the grade Ⅱ included 27 germplasms, of which 66.667% the the accessions of V. amurensis × V. vinifera, and were cold-resistant germplasm; the grade Ⅲ included 27 germplasms, of which V. vinifera was predominant (21), followed by V. amurensis × V. vinifera (5), which were moderately hardy germplasm; the grade Ⅳ included 10 germplasm, all of them were V. vinifera and were low-temperature sensitive germplasms. Based on the affiliation function method and cluster analysis, it could be concluded that among the V. vinifera, Blue French, Petit Manseng, Erhaobaoxiang, Ecolly, Marselan, Cabernet Sauvignon 169, Cabernet Sauvignon and Saperavi had better cold tolerance; V. amurensis 12- 11-5 and 2-5-8 were less cold resistant, but in general the varieties with V. amurensis pedigree were more cold resistant than V. vinifera. Six cold-resistant germplasms were selected: Beihong, 12-5-6, 12- 16-95, 12-10-60, Beimei, Beibinghong; Six low temperature sensitive germplasms included Cabernet Franc, Baigendi, Sauvignon Blanc, Neuburgske, Jiubai and Ruby Cabernet were comparatively analysed for physiological and biochemical indices; With the decrease in treatment temperature, the REC of the 12 varieties continued to increase; the Pro content firstly increased and then decreased; the SS content continued to increase; the POD activity of the highly cold-tolerant germplasm firstly increased and then decreased; and the MDA content continued to increase; the POD activity of the low-temperaturesensitive germplasm continued to decrease; and the MDA content firstly increased and then decreased in the trend of change.【Conclusion】The cold resistance of accessions of V. amurensis × V. vinifera was stronger than that of V. vinifera, and the cold resistance of grade Ⅰ was the strongest, which could be used as a germplasm resource for the subsequent breeding of cold-resistant variety.