RT Journal Article SR Electronic T1 Effects of Variable Rate Nitrogen Application on cv. Barbera Performance: Yield and Grape Composition JF American Journal of Enology and Viticulture JO Am J Enol Vitic. FD American Society for Enology and Viticulture SP ajev.2019.18072 DO 10.5344/ajev.2019.18072 A1 Matteo Gatti A1 Cecilia Squeri A1 Alessandra Garavani A1 Tommaso Frioni A1 Paolo Dosso A1 Irene Diti A1 Stefano Poni YR 2019 UL http://www.ajevonline.org/content/early/2019/01/10/ajev.2019.18072.abstract AB This paper follows a first contribution on the long-term effects of variable rate nitrogen application on vegetative growth and leaf nutritional status of a small Barbera vineyard where three vigor levels classified as low, medium and high (L, M, H) were identified pretrial from Normalized Difference Vegetation Index (NDVI) values determined by remotely sensed imagery (5 megapixel resolution). Variable rate fertilization supplying no N (C, 0 kg/ha), standard rate (S, 60 kg/ha) and variable rate application (VRA) of 60 and 120 kg/ha to H, M and L performed over four consecutive seasons showed that variability among vigor levels was significantly reduced in years 3 and 4, while mean effects related to fertilization strategy were not significant.In this companion paper, L vines confirmed to be the most balanced, suggesting a change in fertilization strategy for no N application in M and H areas and for maintenance supply in L plots. However, significant vigor level x year interactions indicated that within-vigor variability for total yield and berry weight was considerably reduced, whereas concomitant seasonal accumulation in sugar and color in 2014 and 2015 were much less variable within dates across vigor levels, suggesting the effectiveness of the VRA approach. While the main effects of fertilization supply were mostly non-significant, seasonal accumulation of total soluble solids and anthocyanins in 2014 and 2015 showed that plots receiving 60 kg N/ha had lower within-date values than C (no N), suggesting increasing sensitivity over years. However, the L vines had an almost negligible response to increased N supply, and most of the observed responses were primarily due to reduced vine capacity.