Annals of Botany 35: 109-115, 1971
© 1971 Annals of Botany Company
RESEARCH-ARTICLE |
Growth Responses of Sweet Orange Seedlings to Shoot and Root Pruning
C.S.I.R.O. Division of Horticultural Research Merbein, Victoria, 3505 Australia
Received: 13 April 1970
Following combined shoot- and root-pruning treatments the growth of Citrus sinensis (L.) Osbeck seedlings was analysed into responses to post-pruning size and to the part pruned. The treatments were shoots pruned by removing O, 
, or 
of their estimated weight in all combinations with roots pruned by removing O, 
, or of their estimated weight. Responses were measured a year later and are discussed in terms of the mechanisms controlling increment. Total increment was linearly related to initial pruned weight both within and between treatments and there were no interactions between shoot and root pruning in increment of leaf, new stem, old stem, thorn, fibre-root, or tap-root. Root pruning, per gramme of pruned material, reduced increment more than did shoot pruning.
With increasing shoot pruning the ratio of new stem to old stem increased while with increasing root pruning the ratio of fibre-root to tap-root increased. Following shoot pruning the new-stem increment was disproportionately large while following root pruning the increment of top growth was proportionately larger than that of roots.
The results suggest that pruning citrus trees to a constant size at planting could lead to a uniform tree size in the subsequent orchard but that maximum growth would occur on un-pruned trees.