Pyroligneous Acid Affects Grapevine Growth, Yield, and Chemical Composition of Leaf, Pomace, and Juice

In the past decade, many studies have investigated the effects of biostimulants on viticulture. However, the impact of pyroligneous acid (PA) on grape (Vitis vinifera) production has not yet been reported. In this study, PA at varying concentrations (0, 4, 8, and 12% PA) and application frequencies (14-, 21-, and 28-day intervals) were applied to enhance the growth, yield, and quality of grapes (cv. KWAD7-1). The results showed that the treated grapes responded differently to PA application. The 4 and 8% PA showed a nonsignificant (p > 0.05) increase in yield of about 0.37- and 0.18-fold, respectively, compared to the 0% PA. The 12% PA, on the other hand, reduced the yield by approximately 0.03-fold compared to the 0% PA. Carotenoid, total phenolics, flavonoid, and sugar were altered by the PA. Interestingly, the 4% PA significantly (p < 0.05) improved total carotenoids (0.34-fold), total phenolics (0.26-fold), and flavonoids (0.26-fold) compared to the 0% PA. The 4% PA applied at 21-day and 28-day intervals remarkably improved vine and leaf growth, respectively. In conclusion, the 21-day interval of PA application significantly (p < 0.05) improved fruit fresh weight, juice weight, juice volume, press weight, °Brix, pH, salinity, total dissolved solids, electrical conductivity, and titratable acidity. Further study is necessary to assess how PA can influence the metabolites present in grape wine.