Manipulation of citrus trees for new higher-density orchards.
Joubert, F. J. , Plessis, M. H. du , Steenkamp, E. D. , Stassen, P. J.
C.
frikkie@itsc.agric.za;
ARC-Institute for Tropical and Subtropical Crops, Private Bag X11208,
Nelspruit, 1200, South Africa.
Results of a study on the response of Valencia orange, mandarin, lemon
and grapefruit cultivar/rootstock combinations to training systems
(central leader system for high-density planting and multiple leader
system for low-density planting), pruning methods (trees cut back to 50
cm height after planting and trained with new growth; trees shaped
after planting without cutting back; trees shaped after 1 year of
growth), and planting densities (3.0 x 1.0, 4.0 x 1.25, 4.0 x 1.5, 5.0
x 2.0 and 5.0 x 3.0 m, corresponding to 2222, 2000, 1667, 1000 or 667
trees/ha) are presented. The experiment was conducted in Nelspruit
(Valencia orange and lemon), Lydenburg (mandarin) and Malelane
(grapefruit), South Africa during 1996 and 1997. Pruning back a newly
established tree to 50 cm height after planting had negative effects on
tree volume and development compared to the other pruning methods.
Lemon trees were trained more successfully under the central leader
system. Higher levels of manipulation and pruning were necessary when
lemon trees were trained under the multiple leader system, since
leaders of the same strength and development phase were difficult to
find. On the other hand, Valencia orange trees were more easily trained
under the multiple leader system. Trees of lemon and Valencia orange
exhibited greater canopy growth at higher densities (3.0 x 1.0 and 4.0
x 1.5 m, respectively). |
