The influence of rootstock on characteristics of tree growth, fruit productivity and dry matter production of 'Maypole' young apple [Malus pumila] trees

Characteristics of tree growth, yield efficiency and dry matter production (DM) were studied using the columnar-type apple tree 'Maypole' grafted on Marubakaido (Malus. prunifolia Bork. var. ringo Asami), M. 26 and M. 27. Tree growth was largest in trees grafted on Marubakaido followed by that on M. 26 and M. 27, then the expansion of M. 27 slowed down beginning with 4- year- old trees. Trees grafted on to M. 26 and M. 27 had many flower buds. Leaf lengths of the middle of shoot of 5-year-old trees grafted on M. 27 were shorter than those grafted on Marubakaido and M. 26. Total length and leaf area of lateral shoot at each height increment of trees were largest in trees grafted on Marubakaido followed by M. 26 and M. 27. The percent instantaneous incident photosynthetic photon flux density at each height increment of trees was largest in trees grafted on M. 27 followed by that on M. 26, and Marubakaido. Yield per tree and cumulative yield per 10a were largest in trees grafted on Marubakaido followed by M. 26 and M. 27. Yield efficiency was highest in trees grafted on M. 27 follwed by M. 26, and Marubakaido. Fruit weight on trees grafted on to M. 26 and M. 27 was heavier than on trees grafted on Marubakaido. Total DM per year of M. 26 and M. 27 trees compared to that of Marubakaido trees was 40% and 23%, respectively. Assimilation partitioning rate of the fruit increased in proportion to the high dwarfing rate ability of the rootstock, and the assimilation partitioning rate of branches decreased except for that in shoots and thick-root (>2 mm). Total DM per leaf area, fruit DM perleaf DM and area were largest in trees grafted on M. 27 followed by M. 26 and Marubakaido. In conclusion, the present results clearly indicated that the reaction of the tree growth, yield efficiency and dry matter production in columnar- type trees grafted on dwarf rootstock resembled that of normal- type trees.