Different cultivar practices have been applied to vine to promote specific components related to final wine flavor. Some of the cultivar practices are related to vine stress, including leaf removal, grape bunch removal and vegetable cover crops. Some nitrogen and sulfur supplements have been also used directly to leaves during the last stage of the ripening period. Main effects of cultivar practices are related to the final composition of organic acids, volatiles components and phenolics. However some effects on amino acids have been also found.
This paper specifically deals with the effects on tryptophan level because of it has strong effects in the evolution of several other related compounds, including auxins and melatonin. Six different cultivar practices were applied in three replicated in the same vineyard. Evolution of tryptophan levels were determined starting just after grape veraison till harvest date. In some cases, some specific treatments were also evaluated after regular harvest.
Results point out the specific effect of vegetable cover crops and leaves removal to promote higher levels of tryptophan in grapes.