DEVELOPMENT OF AUSTRALIAN ROOTSTOCKS WITH ROOT-KNOT NEMATODE RESISTANCE AND LOW POTASSIUM TRANSPORT
Soils in some major Australian viticultural regions are generally high in potassium content, which is in contrast to viticultural regions in other parts of the world. There is a considerable body of evidence, both from commercial experiences and research results, that the widely adopted high vigour, root-knot nematode tolerant rootstock varieties contribute to negative impacts on wine quality associated with high potassium uptake, high pH and malate levels. Previous findings have shown that in a given year, grafted vine grape juice pH at harvest is highly correlated with the ungrafted rootstock petiole potassium level at anthesis. We demonstrated that this relationship is also present when multiple years of juice pH and ungrafted rootstocks petioles are compared. The mean harvest pH of Chardonnay grafted on 6 commer¬cial rootstocks from 4 vineyards over two consecutive years had a strong correlation (adjusted R2= 0.755) with the 2 year mean potassium content of the ungrafted rootstocks in the field. Likewise, the 8 year mean pH of a rootstock trial with 5 commercial rootstock and 14 experimental rootstocks with Shiraz scions was highly correlated (adjusted R2= 0.502) with the 2 year mean petiole potassium content of the ungrafted field grown rootstocks. To facilitate accelerated breeding of new rootstocks, we have developed a glasshouse based assay for the early selection of rootstocks with low potassium transport to aerial tissues. We demonstrated that the 8 year mean juice pH of grafted vines is also correlated with the ungrafted vine petiole potassium content for plants grown in the glasshouse with supplemented levels of potassium (adjusted R2= 0.501). In addition, we are also screening vines in the glasshouse for resistance to the root-knot nematode Meloidogyne javanica. We are currently screening potential and commercial germplasm for resistance to M. javanica, and have identified a Vitis cinerea accession that transmits resistance as a single dominant gene.
Smith, B.P., Clingeleffer, P.R., Morales, N.B., Thomas, M.R. and Walker, R.R. (2014). DEVELOPMENT OF AUSTRALIAN ROOTSTOCKS WITH ROOT-KNOT NEMATODE RESISTANCE AND LOW POTASSIUM TRANSPORT. Acta Hortic. 1046, 231-240
Meloidogyne javanica, pH, screening, breeding, K+