TY - JOUR T1 - Response of Mature Vines of <em>Vitis Labrusca</em> L. CV Concord to Applications of Phosphorus and Potassium over an Eight-Year Span in Pennsylvania JF - American Journal of Enology and Viticulture JO - Am J Enol Vitic. SP - 237 LP - 244 DO - 10.5344/ajev.1980.31.3.237 VL - 31 IS - 3 AU - Carl W. Haeseler AU - Cyril B. Smith AU - Louis T. Kardos AU - Harold K. Fleming Y1 - 1980/01/01 UR - http://www.ajevonline.org/content/31/3/237.abstract N2 - Experiments concerned with the application of phosphorus (P) to the soil annually at the rate of 50 kg and 150 kg P/ha over an eight-year duration in combination with nitrogen (NP and NP3) or nitrogen and potassium (NPK and NP3K) were conducted in Erie County, Pennsylvania.Yield, number of clusters per vine, cluster weight, berry weight, vine capacity and fruitfulness per retained node were increased by NK, NPK, and NP3K treatments. NPK and NP3K treatments were more effective than NK. Other treatments — N, NP, and NP3 treatments —either were ineffective or inconsistent. Soluble solids percentage of the juice was reduced by the NPK and NP3K treatments. However, a negative correlation was found between yield and soluble solids content of the juice (r = -0.8631). Available soil P was increased by P application at 150 kg/ha. Available soil K was increased by K application at 95 kg/ha. Plant analyses revealed that petiole P increased as a result of applying P to the soil. Positive correlations existed between petiole magnesium (Mg) and petiole calcium (Ca); petiole zinc (Zn) and petiole boron (B); number of clusters per vine and yield. Petiole P and petiole Zn were not associated. ER -