
%0 Journal Article
%A Ruhl, EH 
%T Effect of potassium and nitrogen supply on the distribution of minerals and organic acids and the composition of grape juice of Sultana vines
%J Australian Journal of Experimental Agriculture
%D 1989/02/01
%V 29
%N 1
%P 133-137
%K 
%R https://doi.org/10.1071/EA9890133
%U https://www.publish.csiro.au/paper/EA9890133 
%X Fruiting Sultana vines grown under glasshouse conditions were supplied with 2 K+ levels (0.05 or 0.15 g K+/week) and fertilised with either NH4+ [as (NH4)2SO4] or NO3- [as Ca(NO3)2] as a nitrogen source. Enhanced K+ supply (0.15 g/week) increased K+ concentration in laminae by 1896, in petioles by 59% and in stems by 23%, and reduced Mg2+ of laminae and petioles by 18 and 24% respectively, while Ca2+ was not effected. K+ supply had no effect on tartrate or malate concentration in laminae, stem or roots. Use of NO3- instead of NH4+ as a nitrogen source led to 220% higher citrate and 168% higher malate concentrations in laminae. In roots NO3- supply caused 61% higher citrate, 41% higher tartrate and 26% higher malate concentrations. Higher K+ fertilisation (0.15 g/week) had no effect on fruit yield or sugar content, but increased grape juice pH from 3.95 to 4.08, malate concentration from 0.94 to 1.20 g/ L and K+ concentration from 46.8 to 56.8 mmol/L, thereby causing lower grape juice quality. 
