Promotion of berry ripening by 2,3,5-triiodobenzoic acid in 'Kyoho' grapes

We studied the effects of 2,3,5-triiodobenzoic acid (TIBA) on berry ripenin g of 'Kyoho' grapes (Vitis vinifera L. X V. labrusca L.). Compared with the untreated control, application of 200 mg . liter(-1) TIBA 30 days after fu ll bloom (DAF) reduced berry weight and delayed ripening, increased the tit ratable acidity in the berry, and decreased the anthocyanin content in the peel. TIBA applied 45 DAF, at the beginning of veraison, resulted in higher soluble solids concentration (SSC) in the juice and a higher anthocyanin c ontent in the peel, compared with the control. In a dosage experiment, grap e clusters, sprayed with TIBA at 200 mg . liter(-1), had higher SSC and ant hocyanin levels than those sprayed with 20 or 400 mg . liter(-1) The auxin naphthaleneacetic acid (NAA) clearly delayed berry ripening. Abscisic acid (ABA) enhanced peel coloration, but the SSC was equal to that of the contro l at harvest. When the effects of the anti-auxins: N- (1-naphthyl) phthalam ic acid (NPA) and maleic hydrazide (MH) were compared with those of TIBA on gibberellin-induced seedless berries, NPA- and MH - treated berries had lo wer SSC and higher acidity but no effect on peel coloration. TIBA-treated b erries had a significantly higher anthocyanin content and SSC than did thos e of the control. Thus, TIBA application at the beginning of veraison promo tes the ripening of seeded and seedless 'Kyoho' grapes.