SECONDARY GROWTH AND FLOWERING OF SUMMER-PRUNED ‘KYOHO’ GRAPEVINES AS AFFECTED BY DIFFERENT LEVELS OF NITROGEN

Effects of different levels of applied nitrogen on a twice harvesting system with ‘Kyoho’ grapevines were investigated. 2-year-old sand-grown ‘Kyoho’ (Vitis vinifera L. x V. labrasca Bailey)/ Teleki 5C grapevines in unglazed pots and having one shoot per vine were regularly watered throughout growing season with 1/3 strength Hoagland’s No.2 solutions containing various concentrations of nitrogen (1.5, 3.0, 5.0, 10.0 and 15.0 mM); half were allowed to carry one cluster and the other half were totally cluster-thinned.
After the harvest of first crop (August 11), both vines were pruned back to 12th bud and the uppermost 2 buds were treated with 5% cyanamide (H₂CN₂) solution to induce bursting.

The higher the level of applied nitrogen, the lower the anthocyanin and total soluble solids contents and the higher the acidity of the first crop.
Percentage of bud burst and secondary shoot growth decreased with lowering nitrogen levels.
Numbers of clusters/ shoot and florets/ cluster were the most at 10 mM nitrogen, followed by 15, 5, and 3 mM in that order.
The vines bearing the first crop had fewer clusters and florets than non-bearing vines at each level of nitrogen.
Morphological observation at pruning time, however, revealed that development of inflorescence primordia in buds was not much different among nitrogen treatments.
Total nitrogen contents in the leaves and stems at pruning time were higher, while starch contents were lower for the higher levels of applied nitrogen.

III International Workshop on Temperate Zone Fruits in the Tropics and Subtropics

H. Motosugi, R. Lin, A. Sugiura

https://doi.org/10.17660/ActaHortic.1990.279.65