Leaf Blade versus Petiole Nutrient Tests as Predictors of Nitrogen, Phosphorus, and Potassium Status of ‘Pinot Noir’ Grapevines

Abstract

<jats:p>Grape growers rely on tissue 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 data sets 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’.</jats:p>

Nitrogen Requirements of Pinot noir Based on Growth Parameters, Must Composition, and Fermentation Behavior

“…These guidelines for N status agree with some previous studies (Conradie 2001, Linsenmeier et al 2008, Schreiner et al 2013) but are slightly higher than others for winegrapes (Robinson 2005). The aforementioned leaf blade guidelines are more reliable than the petiole values, as confirmed by regression analysis of the raw plot data from this vineyard, owing to greater year-toyear variation in petioles (Schreiner and Scagel 2017).…”

“…Pot-in-pot vineyard system and experimental design. The data used for this study was obtained over three consecutive growing seasons (2012 to 2014) in a microplot (pot-in-pot) vineyard (Schreiner et al 2013) on Pinot noir grapevines that received five different levels of N at the beginning of their fourth growing season (Schreiner and Scagel 2017). Briefly, grafted 'Pinot noir' grapevines (certified Vitis vinifera L. Pommard clone FPS 91 on 101-14 rootstock, Duarte Nursery Inc.) were grown in 60 L pot-in-pot (Grip Lip 6900T, Nursery Supplies Inc.) microplots installed at the Oregon State University Lewis Brown Research Farm, Corvallis, OR (44.553°N; 123.216°W).…”

“…In addition, irrigation was adjusted seasonally based on vine phenology using θ v so that vines were not limited by water prior to fruit set, but experienced moderate water stress between fruit set and veraison and slight water stress after veraison, as described previously (Schreiner et al 2013). New targets for θ v were determined for this sand:soil mixture based on relationships between θ v and midday leaf water potential (Ψ Leaf ) (pressure chamber, PMS Instrument Company) and stomatal conductance (g s ) (Licor 6400 photosynthesis system or Li-Cor 1600 steady state leaf porometer, LiCor Inc.), and were explained in greater detail previously (Schreiner and Scagel 2017). Before fruit set, irrigation was applied to maintain θ v above 17% to ensure no water limitation.…”

Vineyard Floor Management and Cluster Thinning Inconsistently Affect ‘Pinot noir’ Crop Load, Berry Composition, and Wine Quality

“…The reduced canopy size and yields of Grass vines were attributed to lower vine N. Similarly, others have noted physiological reduction in yield and leaf area in response to lower vine N status (Christensen et al, 1994;Schreiner and Scagel, 2017;Schreiner et al, 2013). Because of the concurrent reductions in yield and leaf area in Grass vines, the effect of floor management treatments on crop load depended on which crop load metric was used.…”

“…Percent leaf blade N was determined at v eraison, using the method described in Reeve et al (2016) and data are reported therein. Leaf blade N was chosen for regression analysis with berry composition data, as leaf blades have been shown to correlate better with vine measures than petioles (Schreiner and Scagel, 2017;Schreiner et al, 2013).…”