Comparative Studies On Effect Of Production Performance Of Three Dwarfing Interstocks In ‘Yueguan' Apple

Dwarf and dense planting is mainstream of apple industry around the world.Due to the improper selections of rootstock,variety,trainning system and uncompleted technology,the cultivated area of the apple with dwarfing rootstocks in China accounted for only 10%of the total cultivated area,and its development is stagnant.Selections of suitable cion/rootstock combination and study the effect of environmental factors is the key for apple compact planting.‘Yueguan'?‘Hanfu'בYueshuai'?,a new apple variety bred by Liaoning Institute of Pomology shows more developing potentials in cold areas.In order to master dwarfing planting techniques of‘Yueguan'apple,the different influence of three dwarfing interstocks on the tree structure of bearing trees,photosynthetic physiology characteristics,and fruit quality and the physiological responses of early young trees under drought,dry and wet alternation and continuous waterlogging of‘Yueguan'apples were studies.The production performance of three dwarfing interstocks were summarized and the optimal combination for‘Yueguan'were identified,which provides a theoretical basis for the production.The results shown as follows.Tree structures,photosynthetic characteristics and fruit quality from the three different interstocks of‘Liaozhen 2',‘GM256'and‘77-34'were investigated and analyzed on 5a-6a's‘Yueguan'apple trees.The results show that‘Liaozhen 2',‘GM256'and‘77-34'were255cm,296cm,344cm in height and 158cm,208cm,225cm in canopy width respectively.Long shoots rate were 5.5%?12.8%?18.2%each.The content of organic acid was the lowest?0.39%?and the sugar-acid ratio was the highest?28.7?in the fruit of‘Liaozhen 2'combination.The net photosynthetic rate(Pn 15.83?mol·m^-2·s^-1),yield of per plant?40.95kg?and per acre(3440kg·667m^-2)of‘77-34'combination were the highest.The comprehensive ranking of the three scion/rootstock combination is‘Liaozhen 2',‘GM256',and‘77-34',according to simultaneous application of variation coefficient and membership function.The studying the effects of water stress on photosynthetic characteristics and function of photosystems of potted‘Yueguan'shows that,with the increase of water stress,the gas exchange parameters of leaves were affected,and photosynthetic efficiency declined.The Pn sequence for four scion/rootstock combinations after being dealt with medium water stress,high water stress and 3 times of alternation of wetting and drying treatment is:standard rootstock>‘77-34'>‘GM256'>‘Liaozhen 2'combination.In waterlogging stress experiment,‘GM256'combination had the highest Pn,while‘Liaozhen 2'combination had the lowest.In addition,water stress increased Fo,W_K and V_J,decreased Fv/Fm,Fv/Fo,PI_abs,and PI_total,the results show that water stress decreased leaves'electron transfer ability on PSII donor and acceptor sides,and the PSI was destroyed too,resulting in a decline in PSII and PSI activity,thus breaking the coordination of the two photosystems.The damage degree of every combinations under drying and alternation of wetting and drying stress is‘Liaozhen2'>‘GM256'>‘77-34'>standard rootstock combination;in waterlogging stress experiment,‘GM256'combination suffered the lightest damage,while‘Liaozhen 2'suffered the severest one.The study on the influence of drying and alternation of wetting and drying stress on carbohydrate of potted‘Yueguan'leaves',shows that the content of soluble sugar and sugar component in each combination were increased with the increase of the number and the degree of drying stress.The contents of starch during drying stress were increased first,then decreased.It indicates that every combinations decrease their cell osmotic potential by increasing soluble sugar and the starch content in leaves,thus,leaves'water retention capacity is increased,and normal cellular metabolism can be maintained,thereby improves drought resistance.In the whole process of stressing,standard rootstock combination ranks at the top,followed by the‘77-34'combination and‘Liaozhen 2'combination ranks at the bottom.The study on the effects of sustained waterlogging on antioxidants of potted‘Yueguan'leaves shows that the contents of SOD,POD,CAT,APX and free proline in leaf and root increased first and then decreased in every combination.It indicates that tree against oxidative stress and increase osmotic adjustment by increasing the activity of protective enzyme and the content of non-enzyme antioxidants.The difference is obvious after waterlogging 7-14d,the protective enzyme activity and free proline content keeps the highest in‘GM256'combination,while the lowest found in‘Liaozhen 2'combination.