ABA SPRAYED TO THE LEAVES INCREASES YIELD IN FIELD-CULTURED GRAPE (VITIS VINIFERA L. CV. CABERNET SAUVIGNON) BY AUGMENTING BERRY SET WITHOUT AFFECTING QUALITY FOR WINEMAKING

QUIROGA AM; CAVAGNARO JB; BOTTINI R

Puerto Vallarta, México

Congreso; IPGSA Conference; 2007

IPGSA

In grapes for red-winemaking periods of water restraint is a tool employed to get higher quality although with lower yield. The rationale is that ABA produced by the water-stressed plant controls water losses by regulating stomata, and therefore photosynthesis with decreases in growth and yield, but at the same time either ABA stimulates polyphenol synthesis and/or smaller berries concentrate in the skin more secondary metabolites. We had previously found however that ABA increases yield in other field-cultured species, either via alleviation of the stress (Ilex paraguariensis) or favoring C assimilation-translocation (wheat). In an attempt to give the stress signal but without their undesirable effects, a field experiment was performed during three years with no soil water restriction. During the 2004-5 season ABA 250 mg.L-1 was sprayed weekly to leaves since 15 days after sprouting; in 2005-6 the treatment was done on the same plants of the year before, or on to a new set; in 2006-7 the spraying was performed on to plants of two, one or zero years of previous applications. In the mid-term ABA did not significantly influence leaf w, stomatal conductance, photosynthesis, or leaf area. However, ABA consistently increased yield during the three years, ranging between 21 and 102%, without affecting polyphenol total index or anthocyan content either in berries? skin or in the wine obtained. Yield increases correlated with an enhanced number of berries per bunch.