Yoshinori Nakao,* Toshihiro Kanie, and Michihiro Furukawa 
*Faculty of Agriculture, Meijo University, Takaki, Kasugai, Aichi 486-0804, Japan (nakaoy@meijo-u.ac.jp)

Liquid fertilizer (N:P:K=0:5:4) containing yeast cell extract improves plant physiological activity. The increase in diameter, weight, and Brix at the end of stage II, immediately before veraison, in treated Muscat of Alexandria berries occurred one week earlier in fertilized than in untreated berries in 2015. The temporary increase of indoleacetic acid (IAA) level in berry after treatment may cause the accelerated changes from stage II to stage III of berry development. However, there were no differences in berry diameter, weight, Brix, and titratable acidity (TA) content at harvest between treated and untreated berries. Berry diameter and weight of Harmo noir (Cabernet Sauvignon × Zweigelt) treated with the fertilizer during growth stages I and II increased in 2016, but there was no difference in Brix or TA between treated and untreated berries. Berry diameter of Merlot fertilized at the end of growth stage II and at early growth stage III in 2016 increased, but there were no differences in berry weight, Brix, and TA between treated and untreated berries. Anthocyanin levels also increased. The temporary increase in IAA level at the end of growth stage III occurred seven days earlier as a result of the treatment. We conclude that the liquid fertilizer treatment might have stimulated grape berry enlargement and coloring.

Funding Support: Meijo University