Wooldridge J.,ARC Infruitec Nietvoorbij 1 |
Olivier M.P.,ARC Infruitec Nietvoorbij 1
South African Journal of Enology and Viticulture | Year: 2014
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 kaollnite. 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 ≤5 0.05) greater trunk circumferences, cane mass, leaf areas and overall wine quality than the shale x 11OR treatment. Yields from grapevines in the granite x 11OR 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 11OR treatments. These differences were attributed to an interaction between the soil and rootstock, with K availabifity and uptake as contributory factors.