TY - JOUR T1 - Recovery of <sup>15</sup>N Labeled Fertilizer by <em>Vitis vinifera</em> L. cv. Cabernet Sauvignon: Effects of N Fertilizer Rates and Applied Water Amounts JF - American Journal of Enology and Viticulture JO - Am. J. Enol. Vitic. DO - 10.5344/ajev.2014.11019 SP - ajev.2014.11019 AU - Alberto B. Iandolino AU - Larry E. Williams Y1 - 2014/02/28 UR - http://www.ajevonline.org/content/early/2014/02/25/ajev.2014.11019.abstract N2 - A study was conducted to investigate the interaction of N fertilization rates and different irrigation amounts on N fertilizer recovery efficiency (REN) of Cabernet Sauvignon in a commercial vineyard near Oakville, California. The fertilizer treatments consisted of a control (no fertilizer) and two 15N labeled ammonium nitrate fertilizer treatments (6.5 and 13.0 g N/vine). The N fertilizer was applied two weeks prior to anthesis. The irrigation treatments were various fractions (0.25, 0.5, and 1.0) of estimated vineyard water use (ETc) with the applied water amount for the 1.0 irrigation treatment from April 7 to September 9 equivalent to 312 mm. Midday leaf water potential (Ψl) was measured throughout the season to monitor vine water status. The labeled N fertilizer was detected in the petioles and leaf blades two weeks after application. Irrigation and fertilization treatments significantly affected midday Ψl. There were significant differences in above-ground vine biomass among the treatments. In general those supplied with more water and/or N fertilizer had greater biomass compared with non-fertilized vines under deficit irrigation. Vine uptake of the 15N labeled fertilizer increased with increasing fertilization rates and irrigation amounts. The REN was significantly different between the two 15N fertilizer treatments (29 and 24% for the 6.5 and 13.0 g N/vine treatments, respectively). The REN at harvest for the 0.25, 0.5, and 1.0 ETc irrigation treatments were approximately 24, 28 and 27%, respectively, though they were not significantly different. The data indicate that fertilizer amount had a significant effect on REN under the conditions of this study and that irrigation rates at full ETc tended to increase RENin this vineyard when compared with deficit irrigation. ER -