New Zealand Journal of Crop and Horticultural Science abstracts
Root pruning of apple trees grown at ultra-high density affects carbohydrate
reserves distribution in vegetative and reproductive growth
Z. U. KHAN
D. L. MCNEIL
A. SAMAD
Department of Plant Science
P. O. Box 84
Lincoln University
Canterbury, New Zealand
Abstract Five-year-old `Braeburn', `Royal Gala', `Oregon Red
Delicious', `Splendour', `Granny Smith', and `Fuji'/MM.106 apple (
Malus
domestica Borkh.) trees growing under an ultra-high density planting system
(20 000 trees/ha) were root pruned in September 1994. Trees were pruned to a
depth of 30 cm with a sharp spade along both sides of the row and between
trees, 20 and 30 cm from the trunk. Root pruning resulted in decreased
tree height, shoot length, branch number, trunk and shoot diameter compared to
the control. Root pruning increased floriferousness e.g., the number of
flowering spurs in subsequent season. Total carbohydrates (TCHO) and TCHO
concentration in tissues of the trees were altered by root pruning treatments.
Elevated shoot TCHO concentration was associated with higher flower initiation
(flowering spurs per tree in the following season) whereas higher root TCHO was
associated with higher total yield. The mean value for root reserves in August
1995 for the control trees was 111 g/plant and 84 g/plant for the
20 cm root-pruned trees. Fruit yields were 4.1 and 2.6 t/ha respectively.
Total yield and average fruit size were reduced by root pruning. The data
suggest that root pruning created a lack of balance between reproductive
characters and potential yield. This may be explained by reduced shoot leaf
area (fewer bourse and shoot leaves) limiting carbohydrate supply and the
effects of root pruning on TCHO, yield, and flowering are consistent with the
predictions of an earlier model.
Keywords apple; ultra high density; root pruning;
floriferousness; vegetative growth; total carbohydrate; reproductive growth
H97063
Received 8 December 1997; accepted 17 August 1998
PDF file of entire paper: medium quality (563K); (scanned from paper original: notes about this process)
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