RESPONSE OF APPLE ROOTSTOCKS AND OF APPLE MAIDEN TREES TO DIFFERENT LEVELS OF POTASSIUM SUPPLY IN SAND CULTURE

In the years 1986–1987 sand culture pot experiment was carried out on M 26 and A 2 rootstocks and on ‘Idared’ apple maiden trees budded on those rootstocks.
Effects of three different concentrations of potassium in solution (0, 10 and 40 ppm of K) were studied in interaction with two different levels of the other macronutrients (high and low). At 10 and at 40 ppm of K in solution, rootstock leaf content was higher at the low level of N, Ca, Mg and P. With increasing K supply the leaf K content increased successively from 0.41% at K-O to 0.92% at K-10 and to 1.47% at K-40 on the average.
At 0 and at 40 ppm of K in solution, leaves of A 2 rootstock contained more K than leaves of M 26 rootstock.
In the second year of study, scion (‘Idared’) leaf K amounted to 0.35 at K-, 0.70 at K-10 and 1.77% at K-40 on the average.
At K-40, scion leaf K content was higher when the level of N, Ca, Mg and P in solution was low.
Trees on A 2 contained more K in their leaves than those grown on M 26 rootstock, but only at K-40. Potassium deficiency symptoms appearing at low levels of K supply were more pronounced on leaves of M 26 rootstocks and on ‘Idared’ budded on that rootstock than on leaves of A 2 and of ‘Idared’ trees on A 2. Increase of K concentration in solution enhanced shoot growth of the rootstocks.
Growth response of apple maiden trees due to increasing K supply was noted only when solution K concentration was raised from 0 to 10 ppm.
Growth of trees budded on M 26 did not depend on the level of N, Ca, Mg and P, in contrast to the trees on A 2 which grew definitely better at a higher supply of those elements.

International Symposium on Diagnosis of Nutritional Status of Deciduous Fruit Orchards

A. Leszczynski, A. Sadowski

https://doi.org/10.17660/ActaHortic.1990.274.33