Petioles were gathered at bloomtime in four trials, one each of `Chardonnay and `Zinfadel' and two of `Cabernet Sauvignon' over 2 years, 1993 and 1994. In each trial, scions were grafted onto 12 to 14 rootstocks. Petioles were analyzed for NO3-nitrogen, NH4-N, K, P, and Mg. NO3-N levels differed among rootstocks by as much as 16-fold (126 to 2064 μg·g–1), NH4-N by as much as 4-fold (253 to 1-28 μg·g–1), K, P, and Mg by about 3-fold (9.7 to 30.6 mg·g–1, 1.8 to 6.3 mg·g–1, and 2.9 to 7.5 mg·g–1, respectively). `Freedom' had the highest levels of NO3-N. `Salt Creek' had moderate levels of NO3-N, but had the highest levels of NH4-N. The rootstock 420A Mgt was consistently low in NO3-N, NH4-N, and K. Freedom was among the highest in K content. The rootstock 44-53 Malègue' had high levels of K and low Mg. Implications for vineyard fertilization programs will be discussed.
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