Experiments to modify grape juice potassium content and wine quality on granite derived soils near Paardenberg

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dc.contributor.advisorSaayman, D.
dc.contributor.advisorFey, M. V.
dc.contributor.authorAgenbach, G.en_ZA
dc.contributor.otherUniversity of Stellenbosch. Faculty of Agrisciences. Dept. of Soil Science.
dc.date.accessioned2008-01-21T10:19:58Zen_ZA
dc.date.accessioned2010-06-01T09:04:28Z
dc.date.available2008-01-21T10:19:58Zen_ZA
dc.date.available2010-06-01T09:04:28Z
dc.date.issued2006-12en_ZA
dc.descriptionThesis (MScAgric (Soil Science))--University of Stellenbosch, 2006.
dc.description.abstractHigh potassium content in grape juice and wine are associated with low quality red wine in warm wine producing countries. In an attempt to reduce the potassium content of juice, must and wine, a field experiment was laid out on the farms Meerlus and Kersfontein in the Paardeberg area near Wellington in 1998 on granite derived soils to investigate the effect of canopy management and fertiliser applications on berry K accumulation and wine quality. Four fertiliser applications, three canopy treatments and a MgSO4 foliar spray were studied. The three fertiliser treatments being: none (control), CaSO4, Ca(OH)2, and MgSO4 applications. The canopy treatments were: thin to two shoots per bearer, tip, vertical shoot positioning (VSP) and the removal of yellow leaves and lateral shoots (canopy 1), thin to three shoots per bearer, top after véraison and VSP (canopy 2) and VSP with top after véraison (canopy 3/control). Magnesium sulfate sprays were applied at véraison for two seasons (1999/00 and 2000/01). Seasonal effects produced the most significant differences in this experiment. Canopy treatments did not affect juice K concentration at harvest. Canopy 1 and 2 produced significantly lower wine pH values at Kersfontein. Fertiliser treatments had no effect on juice K concentration nor did it affect wine quality. Magnesium sulphate foliar sprays did not affect juice K concentration at harvest but significantly lowered juice and wine pH, improved wine colour density and total phenolic content. It appears for this experiment that soil K content before véraison, shoot growth at and after véraison and water stress after véraison were the main factors determining juice K concentration at harvest.en_ZA
dc.format.extent695326 bytesen_ZA
dc.format.mimetypeapplication/pdfen_ZA
dc.identifier.urihttp://hdl.handle.net/10019.1/3035
dc.language.isoenen_ZA
dc.publisherStellenbosch : University of Stellenbosch
dc.rights.holderUniversity of Stellenbosch
dc.subjectGrapevineen_ZA
dc.subjectVitis viniferalen_ZA
dc.subjectBerry potassiumen_ZA
dc.subjectPotassium uptakeen_ZA
dc.subjectK transporten_ZA
dc.subjectDissertations -- Soil scienceen
dc.subjectTheses -- Soil scienceen
dc.titleExperiments to modify grape juice potassium content and wine quality on granite derived soils near Paardenbergen_ZA
dc.typeThesisen_ZA
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