EFFECTS OF PRUNING ON THE BRANCHING HABIT OF MORUS ALBA L. AND THE ABSCISSION OF THE APICES OF THE SHORT SHOOTS

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Abstract
The formation of long shoots and short shoots, growing out from erect one-year-old stems sprouted from six-year-old pruned stumps of mulberry (Morus alba L. cv. Shin-ichinose), has been studied. In contrast to the branches of the unpruned trees showing an acrotonic growth habit, where only several terminal buds elongate, the buds of these stems, including the basal buds, burst simultaneously in the spring. A few upper shoots continued to elongate until autumn, forming long shoots, whilst the other shoots (lateral shoots) formed short shoots, the apices of which abscinded until early June. Excision of the long shoots before abscission of the apices of the short shoots took place resulted in continued growth of the short shoots and formation of long shoots in the upper portion of the pruned stem. The results suggest that the dominance of the upper shoots (long shoots) is maintained by a correlative control system acting between the apices of long shoots and short shoots.