Effects Of Different Pruning Methods On Vegetative Growth And Physiological Characteristics Of Young Apple Trees With Different Combination Of Stock And Scion

The variation in vegetative growth of 2 year old Jazz /M₂₆,Spur Fuji /M₂₆,Spur Fuji/T₃₃₇ rootstock apple trees pruned in four ways,including the top removed,all branches removed,the top and all branches removed,and no pruning were studied.The results showed that:1.The effects on vegetative growth and physiological characteristics of young apple trees pruned in different way on different scion/rootstock combinations was that the diameter of trunk and the shoots length of trees were significantly increased in both removed all branches,and removed the top and all branches treatments.These two branching methed could effectively promote backbone scaffolds,and were rapidly established in young trees to form a reasonable tree structure.The performance in different scion/rootstock combinations was slightly different.In treatment of all branches removed,tree height,diameter,shoot length and bud germination rate increased compared to the control;but total number of shoots,medium shoots,spurs and the rate of flowering decreased compared with control.P content of shoots,leaf area,thickness,N and P content of the top shoot leaves,K content of leaves increased;but the ratio of foliar dried and freshed weight,C content and C/N of lateral shoot leaves decreased compared with control.These changes were more favorable for vegetative growth of the middle and upper parts of young trees.The treatment can obviously promote growth of the trunk and new shoots especially medium and long shoots.In treatment of removed the top and all branches,the bud germination rate was highest;the number of long shoots was more;but the total number of shoots,spurs and rate of flowering were lowest;P and K content of shoot,leaf area and fresh weight of top shoot leaves increased,but C/N of shoots,dry weight,the ratio of foliar dried and freshed weight of top shoot leaves decreased compared with control.The treatment can obviously promote growth of new shoots especially middle and long branches.In the treatment of the top removed,tree height was lower,the total number of shoots,long shoots and spurs were reduced,P content of shoots,chlorophyll content,the ratio of foliar dried and freshed weight,and C/N of lateral shoots leaves increased but N content of lateral leaves decreased compared with control.To some extent,it is beneficial to the accumulation of nutrients in lateral shoot tips.In the control tress,the treeheight and trunk diameter were moderate in all treatments.The total number of shoots and spurs of control trees were the most;flowering of control trees rate was higher;but germination rate,the number of long shoots,shoot growth amount,P and K content of shoot leaves of control trees were lower;P content of 1 year old branches of control trees was lowest compared with other treatments.2.The growth of tree trunks,shoots,leaves and flowering habits were different when the same stock was combined with different scions.The bud germination rate of Jazz was higher than Spur Fuji and more likely to blossom on the same stock M₂₆.Jazz was more dwarfed by M₂₆.After pruning,it was more responsive to the changes of growth of trunks,shoots,leaves and element contents in Jazz /M₂₆ than Spur Fuji /M₂₆.The growth of new shoots were more vigorous,and the accumulation of P and K elements in lateral shoots and the growth of medium and long shoots were more large in Jazz apple than in spur Fuji.Removing all branches in Jazz /M₂₆ was more favorable to the increase of C/N of lateral shoots leaves than Spur Fuji /M₂₆,and also removing the top and all branches was more conducive to the element content distribution of shoots to flower bud differentiation in Jazz apple than Spur Fuji /M₂₆.3.The growth of tree trunks,shoots,leaves and flowering habits were different when the same cultivar was grafted on different stocks.Inhibitory of T₃₃₇ on growth of trunks and shoots to Spur Fuji was more obvious than M₂₆,and the dwarfing,bud germination rate,shoot number of Spur Fuji on T₃₃₇ were higher than on M₂₆,but flowering rate was lower.After pruning,it was more responsive to the changes of growth of trunks,shoots,leaves and element contents in Spur Fuji /T₃₃₇ than Spur Fuji /M₂₆.The growth of shoots were more easily in Spur Fuji /T₃₃₇ but the accumulation of P and K elements of shoots were unfavorable than Spur Fuji /M₂₆.