Analysis On Sunburn Injury Mechanism And Frostbite Reason Of Cerasus Maximowiczii Trunk During Over-wintering Period

Under the background of global warming,the introduction and cultivation practice of landscaping tree species has been carried out widely.In recent years,the problem of overwintering and freezing injury of trees introduced in Shenyang is more and more serious,especially the injury by sunburn and freezing.Dehydration is the main manifestation of damage to plants.In this paper,Prunus maximowiczii is used as the test material and the trunk moisture content as the breakthrough point.The purpose of this study is to reveal the causes of injury by sunburn and freezing during the overwintering period of Prunus maximowiczii trunk,by the analysis of the temporal and spatial distribution of the moisture of trees in the trunk of peach,the relationship between the moisture content and the location of injury by sunburn and freezing,cold resistance at the site of injury,in order to provide technical support for winter prevention of cerasus trees.The conclusions are as follows:(1)The spatial distribution of moisture in Prunus maximowiczii was obvious during the overwintering period.In the lower 100 cm height of the trunk,the moisture content decreased from top to bottom,and the moisture content at the crown was the lowest.The moisture content of phloem(including cambium)was significantly lower than that of xylem.In the radial direction,from the southeast by east(compass87°~132°)to the southwest by west(compass87°~132°),the moisture content is decreasing,and the water content is the lowest in the southwest by west.The moisture content of phloem(including cambium)decreased significantly.(2)The injury by sunburn and freezing of trunk in Prunus maximowiczii area is highly consistent with the spatial distribution of trunk moisture.From the top to the bottom,the degree of injury by sunburn and freezing gradually increased,and the crown was the most serious.On the radial side,from the southeast by east part,the degree of injury gradually increased,and the southwest by west part was the most serious.The main injured parts are phloem.(3)The cold resistance test showed that the cold resistance was the weakest on the north-unexposed and the crown of the trunk.During the overwintering,the north-unexposed and the crown of the Prunus maximowiczii were overheated by the exposure to strong solar radiation and more ground radiation,causing obvious physiological metabolism,too much moisture loss,the cold resistance weakened,and the trees may be injured.However,trees will suffer serious damage when the weather is larger.