PT  - JOURNAL ARTICLE
AU  - J. R. Morris
AU  - D. L. Cawthon
AU  - J. W. Fleming
TI  - Effects of High Rates of Potassium Fertilization on Raw Product Quality and Changes in pH and Acidity during Storage of Concord Grape Juice
AID  - 10.5344/ajev.1980.31.4.323
DP  - 1980 Jan 01
TA  - American Journal of Enology and Viticulture
PG  - 323--328
VI  - 31
IP  - 4
4099  - http://www.ajevonline.org/content/31/4/323.short
4100  - http://www.ajevonline.org/content/31/4/323.full
SO  - Am J Enol Vitic.1980 Jan 01; 31
AB  - Excessive levels of potassium (K) fertilizer (225 to 900 kg/ha) were applied to Concord grapevines for five years in a vineyard with adequate initial levels of petiole K. Petiole K increased from 1.24% (dry weight basis) in control plots to 6.07% in high K plots. Petiole Ca and Mg showed highly significant negative correlations with petiole K, while Mn decreased only slightly with K fertilization. Juice K increased with high levels of K fertilization, resulting in pH increases and titratable acidity reductions in the juice. As fresh juice K content increased, significant increases in pH and acidity loss occurred during juice storage. K levels in the fresh juice and acidity and K loss during storage were highly correlated. K fertilization did not affect total pigment content of the juice, but tristimulus color values were reduced, probably through K-induced pH effects on the anthocyanin molecule. K fertilization reduced the amount of green fruit present at harvest, but had little effect on % soluble solids.