Leaf blade versus petiole nutrient tests as predictors of nitrogen, phosphorus, and potassium status of ‘Pinot noir’ grapevines

Authors: Schreiner, Roger; Scagel, Carolyn

Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/17/2016
Publication Date: 1/1/2017
Citation: Schreiner, R.P., Scagel, C.F. 2017. Leaf blade versus petiole nutrient tests as predictors of nitrogen, phosphorus, and potassium status of ‘Pinot noir’ grapevines. HortScience. 52(1):174–184. doi: 10.21273/HORTSCI11405-16.

Interpretive Summary: Nutrient concentrations in both leaf blades or petioles from Pinot noir grapevines were compared to vine growth, yield, and nutrients in fruit juice to determine which tissue is better for diagnosing the nutrient status of vines. The data were collected primarily from a pot-in-pot vineyard over 4 years where Pinot noir grapevines were grown with different levels of each nitrogen, phosphorus, and potassium. Leaf blades were clearly superior to petioles in predicting vine growth, yield, and must nitrogen levels in vines receiving different levels of nitrogen. Both leaf blades and petioles were about equal in predicting vine responses to varying phosphorus and potassium levels. Based on these findings, we recommend using leaf blades as opposed to petioles for diagnosing the nutrient status of Pinot noir grapevines.

Technical Abstract: Grape growers rely on tissues tests of leaf blades or petioles for routine monitoring of vine nutritional health and for diagnosing potential nutrient deficiency or toxicity. There has been a long standing debate as to which tissue better reflects the nutrient status of vines. A comparison of leaf blade and petiole nutrient concentrations was carried out to investigate which tissue better relates to vine growth, yield, and must nutrient responses of ‘Pinot noir’ grapevines to varying levels of nitrogen (N), phosphorus (P), and potassium (K) supply using data from a pot-in-pot vineyard over 4 years. Leaf blades and petioles were collected at 50% bloom and 50% veraison in each year and N, P, and K concentrations were assessed as predictors of leaf area at veraison, pruning mass at dormancy, yield, and must nutrient concentrations at fruit maturity. Data from commercial ‘Pinot noir’ vineyards were also used to investigate the relationship between leaf blade and petiole N concentrations with must N levels. Results indicated that leaf blades were superior to petioles in predicting vine growth, yield, and must yeast assimilable nitrogen (YAN) responses across a wide range of vine N status at both sampling times. Leaf blade N was a better predictor than petiole N in predicting YAN using datasets from both the pot-in-pot vineyard and commercial vineyards. Relationships between leaf blade and petiole concentrations of P and K and vine response variables generally did not differ and both tissues appeared to be equally effective in predicting P and K effects on growth, yield, and must P or K levels. Although, petiole P was slightly better than leaf blade P at bloom in predicting must P levels; and models including both leaf and petiole K simultaneously as predictors relied only on leaf K. For all three nutrients, sampling at bloom and veraison had a similar predictive strength for response variables. Based on these findings, we recommend using leaf blades as opposed to petioles for diagnosing the N, P, and K status of ‘Pinot noir’.