AN ANALYSIS OF THE RELATIONSHIP BETWEEN BLOOM PETIOLE TISSUE SAMPLE NITROGEN CONTENT AND YEAST ASSIMILABLE NITROGEN IN VITIS VINIFERA WINE GRAPES

Yeast Assimilable Nitrogen plays an extremely important role in the fermentation of grape juice into wine. Suboptimal or superoptimal levels of YAN in must can lead to sluggish and stuck fermentations as well as off aromas and tastes in the final wine. Application of nitrogen fertilizer in the vineyard pre-harvest can increase YAN content in grapes to optimal levels and is cheaper than post harvest YAN adjustments. This article explores the relationship between bloom petiole tissue sample nitrogen content and YAN at harvest do determine if bloom petiole tissue sample nitrogen content can be used as an early season indicator of the necessity of nitrogen fertilizer to raise YAN content in grapes. The relationship is explored by analyzing previously published articles that contain both YAN and bloom petiole tissue sample nitrogen content, compiling the data, and determining through linear regression if a linear relationship exists between the two data points. The article concludes that no linear relationship exists between the two data points and that bloom petiole tissue sample nitrogen content is not an appropriate early season predictor of nitrogen fertilizer need