Soil pH Affects Growth and Nutrient Content of Grapes

Abstract

The grape cultivars Vidal blanc, a French-American hybrid, and Norton, primarily Vitis aestivalis, were transplanted to 19-L pots with soil amended to pH 4.5, 5.9, 7.2, and 8.5. The soil was a mixture of coarse sand and a silty clay loam in the proportion 2 to 1. The experiment was a randomized complete block with two treatments (cultivar, soil pH) and six replications. The objectives of the experiment were to determine vegetative growth and nutrient content of the two cultivars at varying soil pH, and the soil pH within those tested that optimized growth. Vidal blanc was superior to Norton in all growth measurements after 94 days. At pH 7.2 and 8.5, significant reductions in shoot length; leaf area; and leaf, shoot and root dry weights occurred for Norton but not for Vidal blanc. Trends toward lower P, Mg, Fe, and MN and higher B occurred at pH 8.5. Foliar symptoms of Mg and Fe deficiency were noticed for Norton at this elevated pH but not for Vidal blanc. The pH range 5.9 to 7.2 for Norton and 7.2 to 8.5 for Vidal blanc appeared to optimize growth for these two cultivars.