The Effect of Three Rootstock Cultivars, Potassium Soil Applications and Foliar Sprays on Yield and Quality of Vitis vinifera L. cv. Ronelle in South Africa

Abstract

Grape cv. Ronelle was grafted on the rootstocks 110 R, 101-14 Mgt and 143 B Mgt. The effect of 500 and 1,000 kg/ha soil-applied K combined with 0.02 % foliar application of K was investigated. The K fertilizer treatments were applied only once, before bud-break. Three foliar sprays were applied annually, at 2-week intervals, starting at 15 cm shoot length. Results showed that neither high levels of K fertilizer, nor K foliar sprays improved yield and quality of Ronelle on 110 R. Leaf K content was not affected by any of the treatments. Leaf K levels of 110 R were significantly lower as compared to 143 B Mgt. There is no effective cure for established Ronelle/110 R vineyards with K deficiency problems. It is recommended that 110 R may not be used in future for Ronelle. [Z 146]