Effects of Weathered Soil Parent Materials on Merlot Grapevines Grafted onto 110 Richter and 101-14Mgt Rootstocks

  • J. Wooldridge ARC Infruitec-Nietvoorbij1, Private Bag X5026, 7599 Stellenbosch, South Africa
  • M.P. Olivier ARC Infruitec-Nietvoorbij1, Private Bag X5026, 7599 Stellenbosch, South Africa


In a trial under semi-controlled conditions, Merlot grapevines on 101-14Mgt and 110 Richter (110R)
rootstocks were grown in virgin soils developed in highly weathered parent materials derived mainly from
granite and metasediment (shale). Each soil was irrigated at c. -0.075 MPa. The clay fractions of both soils
were dominated by kaolinite. Lime and P were supplied, but no K. Bray II soil K levels from both parent
materials were similar in the field state, but lower in the shale than in the granite when averaged over the
trial period. Petiole K concentrations did not differ between rootstocks on the granite, but on the shale
soils were higher in the vines on 101-14Mgt than on 110R. The granite x 101-14Mgt treatment significantly
promoted (p ≤ 0.05) greater trunk circumferences, cane mass, leaf areas and overall wine quality than the
shale x 110R treatment. Yields from grapevines in the granite x 110R and granite x 101-14Mgt treatments
did not differ significantly. However, the granite x 101-14Mgt treatment produced higher yields than
the shale x 101-14Mgt and shale x 110R treatments. These differences were attributed to an interaction
between the soil and rootstock, with K availability and uptake as contributory factors.


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