Lateral shoots removal has little effect on berry growth of grapevine ( Vitis vinifera L.) ‘Riesling’ in cool climate

Bunch compactness is an important trait that affects the sanitary status and quality of wine grapes. Many studies have demonstrated that canopy managements, such as leaf removal, shoot trimming, and postponed first shoot topping, can effectively reduce compactness. However, few studies have determined the effects of canopy management measures on bunch compactness. Shoot wrapping has been previously shown to elongate the rachis length and reduce bunch compactness. Here, we tested whether the presence of laterals affects cluster growth in Vitis vinifera L. ‘Riesling’ through a field experiment with four treatments over two consecutive seasons: shoot wrapping with laterals, shoot wrapping without laterals, hedging with laterals, and hedging without laterals. Laterals were removed weekly. Lateral removal had little effect on cluster compactness; the effect was shown temporarily and not consistent the growing seasons. The effect of laterals on cluster compactness and rachis length slightly varied with years. The short-term and variable effect of laterals may be explained by the fact that they experienced little competition with clusters.