28 / 68
154
J
ournal of
the
A
merican
P
omological
S
ociety
est number of branches were on PiAu
9-90, and the smallest with the fewest
branches were on B.71-7-22. Graft-
union height at planting was likely af-
fected by the distance between the graft
union and lateral roots and the length of
the rootstock shank, both of which were
very small in a few cases. Most (77% of
the rootstock treatments) trees were able
to be planted at the recommended level
with the graft union between 100 and
150mm above the soil. Trees on PiAu
9-90 were planted such that the average
graft union height was 135 mm. Seven
combinations (23%) were planted with
union heights less than 100 mm, with
the lowest for trees on G.41TC.
Site Effects on Tree Performance.
Over the first 5 years, site (Table 4) and
rootstock (Table 5) affected all aspects
of tree performance. Table 4 includes
data only from the ten sites with a com-
plete set of rootstocks. Colorado was
missing two and Iowa was missing one
rootstock treatment at the initiation of
the experiment, and tree death resulted
in complete loss of one rootstock treat-
ment in Chihuahua. Data from these
three sites were excluded from the
analyses presented in Tables 4 and 5.
Results from Chihuahua, Colorado, and
Iowa, however, are included in the tree
performance data presented by location
in Tables 6-11.
Among the 10 sites included in Table
4, the highest mortality occurred in
Nova Scotia (13%, Table 4); however,
among all sites greatest mortality was in
Chihuahua, with only 77% of the trees
surviving for the first 5 years (Table 6).
Survival was 100% in British Colum-
bia, Minnesota (Table 4), and Colorado
(Table 6).
Site-related tree characteristics are
presented in Table 4. After 5 years, the
largest TCA was recorded for trees in
New Jersey and the smallest for trees in
British Columbia. Trees were also tall-
20
Table 4. Site means for survival, trunk cross-sectional area, root suckers, tree height, canopy spread, yield per tree, yield efficiency, fruit size, and zonal chlorosis of Honeycrisp
apple trees in the 2010 NC-140 Honeycrisp Apple Rootstock Trial. All values are least-squares means, adjusted for missing subclasses.
z
Site
Survival
(2014,
%)
Trunk
cross-
sectional
area
(2014,
cm
2
)
Cumulativ
e root
suckers
(2010-14,
no./tree)
Tree
height
(cm)
Canopy
spread
(cm)
Yield
per
tree
(2014,
kg)
Cumulative
yield per
tree (2011-
14, kg)
Yield
efficiency
(2014,
kg/cm
2
TCA)
Cumulative
yield
efficiency
(2011-14,
kg/cm
2
TCA)
Fruit
weight
(2014,
g)
Average
Fruit
weight
(2012-
14, g)
Zonal chlorosis (%)
2012
2013 2014
BC
100
10.1
6.8
277
120
12.9
22.2
1.4
2.4
302
284
---
57
---
MA
98
13.5
7.4
299
188
8.9
24.8
0.8
2.0
230
222
---
54
41
MI
99
12.1
1.2
257
127
6.7
17.2
0.7
1.6
200
200
---
31
69
MN
100
13.7
0.1
292
186
8.3
17.9
0.7
1.5
174
182
14
49
43
NJ
98
18.1
3.6
335
277
9.7
23.7
0.6
1.4
322
280
---
---
16
NS
87
13.0
0.2
273
115
10.7
26.0
0.9
2.2
164
170
19
41
66
NY
99
15.3
5.5
321
170
8.0
33.0
0.6
2.5
259
239
22
20
25
OH
92
12.4
0.8
231
112
11.5
13.9
1.0
1.3
178
178
---
---
---
UT
95
11.9
1.3
208
129
13.2
15.8
1.2
1.4
---
176
---
---
---
WI
99
12.6
2.9
282
176
8.1
30.8
0.7
2.7
173
230
25
24
15
Average HSD
8
3.5
2.9
27
21
4.8
7.2
0.3
0.4
31
21
11
15
12
z
Mean separation in columns by Tukey's HSD (
P
= 0.05). HSD was calculated based on the average number of observations per mean.
z
Mean separation in columns by Tukey's HSD (P = 0.05). HSD was calculated based on the average number of observations per mean.
Ta l 4.
ite means for sur ival, trunk cross-sectional area, root suckers, tree height, canopy spread, yield per tree, yi ld effic ency fruit size, and zonal chlorosis of
Hon ycrisp apple trees in the 2010 NC-140 Honeycrisp Apple Rootstock Trial. All values are least-squares means, adjusted for missing subclasses.
z