Characterizing potassium uptake and accumulation by grape rootstocks: The xylem potassium approximation
Titel:
Characterizing potassium uptake and accumulation by grape rootstocks: The xylem potassium approximation
Auteur:
Swanton, Bruce A. Kliewer, W. Mark
Verschenen in:
Journal of plant nutrition
Paginering:
Jaargang 12 (1989) nr. 2 pagina's 145-158
Jaar:
1989-02
Inhoud:
Richter 110 (110R), a relatively low-vigor grape rootstock, and Rupestris St. George, a high-vigor rootstock, were grown in a flowing nutrient solution system to evaluate their K uptake and growth characteristics, and to identify the K uptake parameter(s) which best reflect the greater foliage [K] found in St.George relative to Richter 110. The total K taken up divided by the total water absorbed during a 24-hour uptake period, termed the xylem K approximation (Cxka). more consistently distinguished St.George from 110R than root K influx. Cxka was also more stable than K influx against changes in root total surface area, root:shoot area ratio and rate of foliage growth per unit of root area. Larger vines within each cultivar group had lower values of K influx and Cxka than smaller vines. This was ascribed to: 1) the greater root:shoot ratio of larger vines vs smaller vines, and 2) that larger vines produced less foliage per unit of root system than smaller vines. For both reasons the demand for K uptake per unit of root in larger vines was less than that of smaller vines. The decline in K influx with increased root system size was 2.4 times greater than the decrease in Cxka over the same range. The Cxka value, used together with K influx, is suggested as a useful means of evaluating the nutrient uptake characteristics of different cultivars and species of Vitis.
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