CLOSE
PLANTING OF AVOCADO
Bruno Razeto, Thomas Fichet and José Longueira.
University
of Chile, Casilla 1004. Santiago, Chile.
Additional index words: Bacon, planting density,
growth, yield, fruit weight, fruit maturity.
This work is the continuation
of the paper presented at the World Avocado Congress II in California (1992)
which reported results of the six initial years of a trial where three planting
distances (6x6, 5.5x3 and 4x2 m) are being compared in an experimental grove of
the cv. Bacon. During the seventh and eighth years trees continued to grow
inversely proportional to planting density, the grove becoming somewhat crowded
at 4x2 m. Conversely; at 6x6 m there was plenty of space between trees. At
5.5x3 m trees formed an equilibrated hedge. Yield per tree continued to
increase at the three densities up to the seventh year. At the eighth year it
strongly decreased at 4x2 m while it remained almost stationary at the other
two densities. Yield taken on a per hectare basis continued to be quite
proportional to planting density and reached the highest level at 4x2 m the
seventh year (near 44 metric Ton/Ha.). Despite the reduction in tree production
the eighth year at this planting distance, yield per hectare was still a little
higher than at 5.5x3 m. At 6x6 m yield was much lower than at 5.50. Individual
fruit weight and maturity were not affected by planting distance.
1. Introduction
This work is the continuation
of the paper presented at the World Avocado Congress II in California (Razeto
et al., 1992) on the effect of close planting of avocado trees (cv. Bacon)
after the six initial years of the trial. In that opportunity it was reported
that when comparing three planting distances (6x6, 5.50 and 4x2 m) the trees
started to form dense hedges five and six years after planting at the latter
two spacings, respectively. From the fourth year on, yield per tree started to
be proportionally lower at closer spacings. However, yield taken on a per
hectare basis continued to increase in accordance with planting density up to
the sixth year, becoming extremely high particularly with the highest density
planting.
The current paper
reports the results obtained in the two years that followed (7th and 8th)
concerning tree growth, fruit production and fruit size.
2. Material and Methods
"Bacon" trees grafted on Mexicola
rootstock were planted in the Spring of 1984 on a uniform and deep clay loam soil,
located 50 km West of Santiago. Blocks of three rows were planted for each
distance to be
tried. Eight, 15 and 22 trees per row were respectively planted at each
distance, respectively. Planting distances being tried are 6x6, 5.50 and 4x2
meters. One row of "Hass" trees was planted between blocks as a
pollinator, leaving a 6 m space between blocks (Figure 1).
Trees were grown without any
pruning or thinning. Periodical furrow irrigation was done during spring,
summer and fall. Yield per tree was weighed yearly. Fruit size and oil content
were determined yearly starting with the 1990 harvest, taking a random sample
of six fruits per tree. Trunk diameter was measured in March 1990, 1991 and
1992.
All measurements and
samplings were done in six trees per treatment, located in the central row of
each block.
3. Results and Discussion
During the seventh and eighth
years in the 4x2 and 5.5x3 m spacings the trees continued to grow both in
height and towards the space between rows since they had already formed a dense
hedge on the rows. In the 4x2 spacing some branches of adjacent rows were
almost touching each other. Conversely, at 6x6 m, although the trees grew in
all directions, there still existed a wide space among them. At the 5.5x3
arrangement the hedge was fairly balanced.
The trunk diameter kept
increasing inversely proportional to the plantation density resulting in
greater differences among treatments relative to the sixth year (Table 1).
Yield. In the seventh year, the individual
production per tree continued to increase in the three planting densities. In
the eighth year it increased slightly in 5.5x3 m. decreased somewhat in 6x6 m,
and decreased significantly in the 4x2 m spacing (Figure 2). The abrupt
production drop resulting from this higher plantation density would probably be
due to the debilitation of trees and/or the excessive shading which they
already presented.
Production in tons per
hectare in the 4x2 m spacing continued to increase in the seventh year reaching
the record of 43.7 ton/ha but dropping in the eighth year. Despite this drop,
production was still higher than at the 5.5x3 and 6x6 m spacings where it
remained quite stable and proportional to planting density from the seventh
year on (Figure 3).
Fruit weight and
maturity. As shown in Table 2. both
in the seventh and eighth years the average individual weight of fruits showed
no significant differences according to the planting spacings.
The weight reached by fruit
is the normal for the cultivar. With respect to maturity, an adequate oil level
(about 12%) was achieved in October of the seventh and eighth years at all
densities.
From the results
obtained in this investigation it is concluded that avocado trees planted at
much closer spacing than the traditional one in order to form a hedgerow is a
promising system for the Bacon cultivar and probably for others of similar
growth habit and production (erect tree with moderate vigor and precocious
production) particularly when the goal is to achieve a rapid production even at
the expense of a Possible shorter life of the grove.
4. References
Razeto, B.; J.
Longueira and T. Fichet. 1992. Close planting of avocado. Proc. of Second World
Avocado Congress. California. pp. 273-279.