HORTICULTURAL EXPERIMENT STATION, SIMCOE
ANNUAL REPORT OF COOPERATIVE REGIONAL PROJECT NC-140
Rootstock Effects on Pome Fruit Trees
January 1 to December 31, 1996
John A. Cline and Mary Bom
I. PROGRESS AND PRINCIPAL ACCOMPLISHMENTS
Objective 1: Evaluate rootstock and multiple genetic systems in different
environments.
1990 NC-140 Gala Rootstock Trial (Table 1.)
Based on trunk cross-sectional area in year seven (1996), M.27 E. trees
were the smallest and P.1 , M.26 E., and Mark were the largest with only
small differences in tree size among the other rootstocks (M.9 E., MAC.39,
O.3, and B.9). Cumulative yield in year 6 was highest for P.1 and B.9 and
lowest for M.27. Cumulative yield efficiency was greatest for M.27E and
slightly less for the other rootstocks, with the exception of M.26E. and
P.1 where it was considerably less. Average fruit size was similar among
rootstocks in 1996.
1994 NC-140 Dwarfing rootstock trial with the scion cv. 'Gala'. (Table
2).
In year three (1996) five rootstocks (M.27E, P.22, P.16, B.491, and V.3)
were significantly smaller, and eight rootstocks were significantly larger
than M.9E (Table 2). Tree size (TCSA) ranged from
51-252% of M.9E with M.27E and G.65T being the smallest and largest, respectively.
O.3 and Mark had significantly more flower clusters per tree than M.9E,
which resulted in a greater crop load and yield. Fruit from trees on M.9
Pajam 2 were significantly greater in size in comparison with M.9 E, whereas
fruit from B.469 were significantly smaller than M.9E.
With respect to cumulative yield efficiency, trees on P.22, P.16, B.469
and O.3 have been
most efficient, whereas trees on M.26E, V.1, and G.65T least efficient.
Tree height and spread differed among rootstocks. Trees on M.27E, B.491,
and P.16 had significantly larger tree height:spread ratios in comparison
with M.9E indicating that these trees had disproportionately more leader
growth than lateral branching.
1994 NC-140 Semi-dwarfing rootstock trial with the scion cv. 'Gala'. (Table
3).
Of the six rootstocks under evaluation, trees on M.26E and V.2 were similar
and significantly smaller than G.30, P.1, G.11, and CG.13. Trees on M.26E
and G.30 had the greatest number of flower clusters per tree in 1996. V.2
has had the highest annual yield, cumulative yield, and cumulative yield
efficiency to date. Average fruit size has been similar between rootstocks.
Trees on G.11 and CG.13 did not bear any appreciable yield in year two (1995)
or three (1996).
Objective 2: Evaluate the performance of various rootstock/scion combinations
under different orchard management systems.
1990 NC-140 Orchard Systems Trial (Table 4 - 'Empire';
Table 5 - 'Jonagold').
The 1990 orchard systems trial produced a very light crop of 'Empire' and
'Jonagold' in 1996 following a moderate crop of each the year prior. Where
necessary crop load in 1996 was adjusted by hand-thinning to commercial
levels since the performance of chemical thinners in this block has been
marginal at the best of times. Crop load for 'Empire' and 'Jonagold' ranged
from 9-42 and 3-31 fruit per tree, respectively. Yields in 1996 for 'Empire'
and 'Jonagold' ranged from 2.6-6.6 and 0.9-9.4 MT/ha, respectively. Because
of the high variation in yield resulting from a combination of winter injury,
poor fruit set, and drought in 1995, no system or rootstock significantly
outperformed another. For 'Empire', B.9 and P.1 rootstocks were less efficient
and productive than the other rootstocks. For 'Jonagold', M.9E, M.26E and
P.1 were least efficient and productive. The most productive rootstock based
on cumulative yield per trunk cross-sectional area, irrespective of orchard
system, continues to be M.9E for 'Empire' and Mark for 'Jonagold'. However,
production efficiency based on cumulative yield per canopy volume continues
to indicate that Mark and B.9 are comparable with M.9E for the scion 'Empire',
while Mark remains the most efficient rootstock for 'Jonagold'. Trees on
P.1 and M.26 have been less efficient than the other rootstocks.
II. USEFULNESS OF FINDINGS
Objective 1:
This is the second year of significant cropping for two of the three trials
within this objective, and therefore, some observations must still be consider
preliminary at this stage. With respect to the 1994 plantings, based on
the data gathered in Ontario B.9, M.9 Pajam 2, Mark and O.3 exceed the precocity
of M.9 E. Yield efficiency of O.3, B.469, P.16, and P.22 exceeds that of
M.9E while yield efficiency of M.26 E, V.1, and G.65T is less than M.9E.
This research indicates that significant differences among the M.9 clones
continues to exist after year three. In the future, careful monitoring of
the specific advantages and disadvantages of these clonal differences should
be made. G.65T is clearly highlighted as having no commercial potential
because of its excess vigour and low precocity.
The NC-140 plantings are of utmost importance to Ontario for gaining access
to and trialling of new rootstocks from around the world. The detailed and
objective evaluation of these rootstocks will provide growers with the information
needed to select the most appropriate rootstocks for their needs when they
become commercially available in the future.
The cooperative testing of the new Vineland (V.) series rootstocks through
the NC-140 technical committee will help conduct a comprehensive and rapid
evaluation of this rootstock over a wide range of soil and climatic conditions.
Objective 2:
Orchard systems at moderate to high densities (1500-2500 trees/ha) on M.9E,
B.9, Mark, and M.26E have been more productive than lower density systems
on more vigorous rootstocks.
Total production in year 7 remains closely related to initially planting
density in the order of slender spindle > vertical axis > central
leader.
The NC-140 orchard systems plantings are regularly used as demonstration
plots for visiting apple growers, extension personnel, and research scientist.
The research data collected in this trial will help to establish base-line
production and economic records for the various orchard system/rootstock
combinations which can be later utilized by orchardists in Ontario.
III. RESEARCH PLANNED FOR 1997.
Objective 1:
1. Research on all three experiments will continue as outlined in the protocols
developed by the NC-140 technical committees.
2. Trickle irrigation was installed in 1996 in the 1994 NC-140 'Gala' dwarfing
and semi-dwarfing rootstock trial.
Objective 2:
1. Research will continue as outlined in the protocols developed by the
NC-140 technical committee.
2. A study initiated in 1995 to evaluate the effect of rootstock, orchard
system, and crop load on fruit quality and mineral status continues as planned.
This project is partially supported by the IDFTA through one of their annual
research grants.