Comparison of Structural and Nutritional Composition between Alternate and Annual Bearing Trees of Japanese Persimmon (Diospyros kaki Thunb.) 'Maekawa Jiro'

Abstract

The structure and chemical composition of annual and alternate bearing trees of the Japanese persimmon (Diospyros kaki Thunb.) 'Maekawa Jiro' were studied. Alternate bearing trees (Alternate Group) and annual bearing ones (Control Group) were up-rooted, dissected, and the nutritional status of their parts analyzed. The data were examined with respect to their previous histories and chemical analyses. 1. Alternate Group exhibited large yearly fluctuations in the number of normal flowers (and yield), but their percentage of physiological fruit drop (June drop) was similar to that of the Control Group. The former had smaller fruits with lower Brix values than had those of the latter. 2. The Alternate Group had a smaller percentage of dry matter, particularly in their above-ground parts than had that of the Control Group. 3. The leaf N and P contents of the Alternate Group before and during the bearing years were low as were the P and K contents in 1-yr-old dormant wood. Likewise, the N level in the thick roots and P content in the other vegetative parts were low. 4. The 1-yr-old dormant wood in the Alternate Group had very low starch content in the "On" years, wheras it was consistently high in the Control Group. In both groups, the root starch content was higher than that of the aerial parts. The starch content of all parts of Alternate Group trees following a heavy crop were lower than those of the Control Group. Thus, alternate bearing 'Maekawa Jiro' trees is characterized by excessively high yields in the bearing "On" years, leading to poor nutritional levels and vegetative growth accompanied by low yields in the following "Off" years.