Effect of pre-bloom anti-transpirant treatments and leaf removal on 'Sangiovese' (<i>Vitis vinifera</i> L.) winegrapes

Abstract

Recent trials have shown that basal shoot leaf removal at pre-bloom is effective in reducing fruit-set and yield, leading to better grape quality composition. The present trial was designed to determine whether similar results can be achieved with 'Sangiovese' vines by testing a pre-bloom spray of film-forming anti-transpirant (P) against pre-bloom hand defoliation of basal shoots (HD) and no defoliation (C). The results of our threeyear experiment show that, compared to C, P reduced net assimilation of treated leaves for 20-40 days and photosynthetic compensation was not found after treatments in the upper untreated leaves of P and in the remaining upper HD leaves; berry-set, cluster weight and yield were significantly reduced in P and HD; bunch compactness decreased in HD, with P clusters registering an intermediate value; must soluble solids content (°Brix) and pH of P and HD were higher; no differences were found among treatments for titratable acidity. Berry and skin weight and anthocyanin content of P and C berries were similar, whereas HD berries, which were fully exposed to ambient light and temperature throughout each season, showed higher skin weight and skin weight-to-berry weight ratio, but a decreasing of total skin anthocyanins content compared to C and P.