Overhead arbor tree shape affects tree development and increases fruit yields in sweet cherry

We evaluated different shapes of sweet cherry trees for their effects on cherry production, and tree development. The tree shapes were a palmette shape (4×7 m), a Y-palmette shape (7×4 m), an open-vase shape (5×4 m), and an overhead arbor shape (6×5 m). After inducing branches on trees of each shape in the first 3 years, tree growth, fruit production, flower bud formation, and labor hours to shape trees were assessed after seven years. The number of new branches was much higher in the overhead arbor shape (10,666 10 a^-1) than in the palmette shape (2,867 10 a^-1), the Y-palmette shape (6,178 10 a^-1), and the open-vase shape (7,250 10 a^-1). The average length of new branches was much smaller in the overhead arbor shape (39.6 cm) than in the palmette shape (55.5 cm), the Y-palmette shape (60.6 cm), and the open vase shape (44.0 cm). The results indicate that increasing numbers and decreasing length of new branches are related to tree shape of sweet cherry. Fruit yields were higher 1.86-3.15 times with the overhead arbor shape (916 kg 10 a^-1) than with the palmette shape (291 kg 10 a^-1), the Y-palmette shape (493 kg 10 a^-1), and the open-vase shape (478 kg 10 a^-1). A similar trend was observed among the four shapes in the levels of flower bud formation. The lowest amount of labor time was required for developing the open-vase shape (21.9 h 10 a^-1) because new branches were not induced artificially in this shape, while the maximum labor time was required to develop overhead arbor shape (47.2 h 10 a^-1). The study demonstrated that the overhead arbor shape has potential for small farmers in South Korea.