Study Of The Cold Tolerance Of Wine Grape Roots In Helan Mountain Region

The cold damage caused by low temperature is always the main reason for the death of plant.To study the relation between cold hardiness and physical,chemical indexes when processed cold acclimation,11 3-year-old red varieties and 6 3-year-old white varieties from the experiment vineyard in Wine School of Ningxia University were used as material.17 well-prepared samples were placed in temperature control refrigerator to be trained.The temperature was 40??-3??-6??-9??-12?.Some indexes like FW/BW,conductivity,soluble sugar,soluble protein,MDA,free proline were analyzed to determine the relation between the change of these factors and cold hardiness.Meanwhile,the effect of age on the cold hardiness of the root system of Cabernet Sauvignon and Merlot were studied,and the effects of thickness of soil for winter burying and digging-out time on the cold damage of grape root system is also a part of the project.The result of the experiments are as follows:1.As the temperature of cold acclimation decreases,the tendency of the conductivity of 17samples show very obvious "S" shape.After matching the tendency with Logistic Regression,we calculate the LT50(lethal temperature 50%).Among red varieties,the LT50 of Pinot Noir and Tannat are the lowest,which are-9.43? and-9.89?.The rank of LT50 of the otheer red varieties,from low to high,is Petit Verdot,Cabernet Gernischt,Cabernet Franc,Dunkelfelder T,Meili,Merlot,Cabernet Sauvignon,Syrah,Marselan;the LT50 of white variety Vidal is-17.64?,which is much lower than the others.The rank of LT50 of other white varieties,from low to high,is Petit Manseng,Chardonnay,Riesling,Italian Riesling,Viognier.2.As the temperature of cold acclimation decreases,the contents of soluble carbohydrates,soluble protein,free proline,and MDA increase together.However,some indexes of some varieties decreases in lower temperature,the range of increase and decrease varies a lot in different varieties.Among red varieties,in every training temperature,the indexes of Cabernet Gernischt,Cabernet Franc,and Pinot Noir are higher than the others.Among white varieties,the content of soluble protein and MDA of Vidal are higher than the the others,and as the temperature decreases,the range of change keeps increasing,which means that the cold hardiness of Vidal is better than the other white varieties.3.The LT50 of the root system of Cabernet Sauvignon and Merlot decreases as the vine gets older,which means that after years of cold acclimation,the cold hardiness of the root system of Cabernet Sauvignon and Merlot in Helan Mountain region increases.The rate of the decrease of Cabernet Sauvignon is 0.75?/year,and 0.19?/year for Merlot,respectively.4.During dormancy season,in the soil 20cm under the ground,the lowest temperature can be-7? to-8?,the root system of vitis.Vinifera will be extremely damaged in this temperature;in the soil 30cm under the ground,the lowest temperature can be-3? to-6?,the root system of vitis.Vinifera will be partially damaged;in the soil 40cm under the ground,it is safe for the root system to overwinter.Thus,for Helan Mountain Region in Ningxia,the depth of burying should be more than 40cm.