Performance of 'Rakuraku Fuji' Apple trees on JM.7 and M.9Nagano rootstocks, and M.9 Nagano/Marubakaido interstem combination in Japan

Trees of 'Rakuraku Fuji' apple (Malus X domestica Borkh.) on JM.7, M.9Nagano rootstocks and M.9Nagano/Marubakaido (Malus prunifolia Bork. var. ringo Asami) interstem combination were evaluated for growth and productivity in a high density orchard situation on a deep volcanic ash soil in Azumi, Nagano, Japan. By the 5th leaf, trees on JM.7 and M.9Nagano/Marubakaido exceeded the alloted space (2 x 4m), and every other tree in the rows was removed following harvest. After 8 growing seasons, trees on JM.7 and M.9Nagano/Marubakaido had a similar trunk cross-sectional area (TCA) and were larger than trees on M.9Nagano. Trees on M.9Nagano had a greater cumulative yield efficiency through the 6th year. In the 8th year, trees on M.9Nagano/Marubakaido had a greater cumulative yield efficiency than trees on JM.7 and M.9Nagano. Calculated yields per ha based on 2 x 4m spacing (1250 trees per ha) of trees on M.9Nagano/Marubakaido and JM.7 were greater than those on M.9Naganc, through the 5th year after which trees were thinned to 625 per ha. In years 6 through 8, trees on M.9Nagano had the highest calculated yield per ha. Trees on JM.7 and M.9 Nagano/Marubakaido were too vigorous for high density planting with less than 2 x 4 m spacing on the deep volcanic ash soils found in Nagano.