Light Transmission and Fruit Quality Through Partial Canopy Modification in the ‘Gamhong’/M.9 Slender Spindle Apple Tree

Lee, D.Y.; Park, M.Y.; Kweon, H.J.; Song, Y.Y.; Lee, Y.S.; Lee, D.H.; Nam, J.C.; Cho, Y.S.

Light Transmission and Fruit Quality Through Partial Canopy Modification in the ‘Gamhong’/M.9 Slender Spindle Apple Tree

2021

In Korea, slender spindle is one of the most widely-used tree forms for high-density apple planting orchards. However, as the age of the tree increases, the light distribution pattern of the slender spindle tree’s canopy becomes unfavorable for robust apple production, particularly at the lower levels of the tree’s canopy. As a result, because it is difficult to change the overall tree form, partially modifying the canopy can be an effective way to solve these problems. This study was conducted in order to analyze proper canopy management practices through the evaluation of the canopy’s light environment and the fruit quality of the ‘Gamhong’/M.9 slender spindle apple tree. Three different treatments were applied to the partial canopy, particularly to the upper levels, where the light environment is likely to be poor. Treatment 1 (T1) consisted of cutting back lateral branches and shortening the canopy width, Treatment 2 (T2) focused on the bending of lateral branches under the row, and Treatment 3 (T3) used the maintenance of the spindle shape as a control. T1 showed the highest light transmittance to the lower portion of the canopy compared to other treatments, resulting in the production of large and well-colored apple fruit and higher floral bud differentiation. On the other hand, T2 showed reduced light transmittance, due to the overlapping of branches which further increased shading in lower levels of the canopy, causing lower coloration in the fruit. Collectively, our results suggest that keeping the canopy narrowlyshaped by restraining lateral branches above the lower levels of the canopy is the most efficient canopy management practice to improve light distribution and fruit quality in the ‘Gamhong’/M.9 slender spindle apple tree.

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