Abstract
The effects of different levels of fertilizer application on peach trees, cv.‘Sanyo Suimitsu, ’on Prunus tomentosa (a dwarf rootstock) were investigated by sand culture method. Trees on P. persica (a vigorous one, generally used) were also tested for comparison purposes.
1. Supplying a high level of fertilizer (N: 160 ppm) from blooming until stone hardening caused vigorous shoot growth and delayed fruit maturation on either rootstock. Fruits harvested were bigger in size but their sugar content was lower than those of control trees supplied with a standard fertilizer solution (N: 40 ppm) throughout the season.
2. Supplying the strengthened fertilizer from one month before blooming inhibited the growth of both shoots and roots, especially in the trees on P. tomentosa. Fruit maturation was also delayed and their quality was unacceptable.
3. Diluting the standard fertilizer to 1/4 normal strength at or after stone hardening accelerated the termination of shoot growth and fruit maturation. Harvested fruits contained a higher level of sugar, though their size was smaller than those of control. These effects were more remarkable in the tree on P. tomentosa than on P. persica.
