HEAVY-CROPPING CLONES IN NON-VIRUS-FREE APPLE-VARIETIES
Heavy-cropping clones in non-virus-free apple-varieties Heavy-cropping clones originating from natural somatic mutations of the apple-varieties 'James Grieve', 'Cox Orange', 'Jonathan' and 'Boskoop' are described. After a test period over 11 years the crop yields per trunk-circumference of these clones are distinctly higher than the mean values of the parent clone-group. In the second part using the apple 'Cox Orange' as an example the variation of size, set and specific gravity of the fruits is considered indicating possible causes for differences in crop yields within these clones.
Silbereisen, R. (1977). HEAVY-CROPPING CLONES IN NON-VIRUS-FREE APPLE-VARIETIES. Acta Hortic. 75, 87-96