Arginine Levels in Grape Canes and Fruits as Indicators of Nitrogen Status of Vineyards

Abstract

A field nitrogen trial involving 80 six-vine plots of `Thompson Seedless9 grapes in 1971 and 1973 showed highly significant (P<0.001) curvilinear regressions between crop yields and arginine in canes, arginine in fruits, and nitrate in petioles. The respective correlation coefficients in 1971 and 1973 were 0.71 and 0.79, 0.72 and 0.83, and 0.69 and 0.59. Arginine in dormant canes and in mature fruits, and nitrate in petioles, were all significantly correlated linearly with each other in both years. In addition, arginine in mature fruits was significantly correlated with pruning weights, with the respective coefficients for the two years being 0.61 and 0.74. The concentration of arginine in fruits was independent of the level of total soluble solids between 19° and 22°Brix. In this cultivar the critical deficiency ranges were 4 to 6 mg per g dry weight for arginine in dormant canes, 400 to 500 µg/ml juice for arginine in fruits at harvest, and 0.12 to 0.15% dry weight for nitrate in petioles at bloomtime. The corresponding adequate ranges were respectively 6.1 to 14 mg, 501 to 1150 µg, and 0.16 to 1.25%.