International Journal of Horticultural Science and Technology (2021) Vol. 8, No. 3, pp. 227-233
227
International Journal of Horticultural Science and
Technology
Root Growth Changes in the Winter Planting of Young
‘Miyabi Fuji’ Apple Trees
Alisher Botirov
1
and Osamu Arakawa
2*
1. The United Graduate School of Agricultural Science, Iwate University, Morioka, Iwate 020-8550, Japan
2. Faculty of Agriculture and Life Science, Hirosaki University, Hirosaki, Aomori 036-8560, Japan
ARTICLE INFO
ABSTRACT
Article history
:
Received: 17 November 2020
Received in revised form: 5 February 2021
Accepted: 19 February 2021
Article type:
Time of planting is a normal part of any agricultural operation. It
has a particularly importance in water-challenged areas where soil
moisture is an issue. During the winter months in these areas, there
is usually sufficient precipitation to maintain adequate water
content levels in freshly planted trees. However, during the
summer and early autumn, there is very little precipitation. This
can adversely affect young trees. In this study, measurements were
taken to determine root growth and variations in the upper parts of
apple trees that were planted in the winter, compared to those
planted in the spring when planting usually takes place. To do so,
one-year-old 'Miyabi Fuji', grafted onto Marubakaido (Ma) (
Malus
prunifolia
'Ringo') and M.9 rootstocks, were examined from January
through May. The results showed dramatic changes in root growth
from March (average root length less than two cm before March) to
May (average root length longer than 10 cm) for both
rootstocks. Furthermore, trunk moisture content increased over
time (51.8% in January and 56.1% in May on M.9). Although root
growth in the young apple trees occurred, it is unknown if root
water absorption began before or at the same time of the root
growth. Root growth developed favorably because of the soil
moisture generated by the winter precipitation. We found
satisfactory root growth and tree moisture content changes in the
trees used in the study, leading us to recommend winter planting in
areas where water resources are limited in the non-winter months.
Research article
Keywords:
Growing season,
Rootstock,
Water content,
Root growth,
Shoot growth.
Introduction
The apple (
Malus domestica
Borkh.) is one of the
worlds’ most widely cultivated fruits (
van
Vuuren et al., 2006). Commercial apple
production takes place mostly in temperate
climate areas where snowfall normally falls
during the winter. Young apple trees are usually
*
Corresponding Author
ʼ
s Email: oarakawa@hirosaki-u.ac.jp
planted in early spring or late autumn, although
planting times differ depending on weather
conditions (Arakawa et al., 2014). In recent
years, the spring planting of fruit trees has
become a normal practice in temperate areas as
well as in arid areas with limited water
resources (Kikuchi et al., 2003). However,
planting in water–challenged areas impacts
young plant's root, especially those of young
Alisher Botirov & Osamu Arakawa
Int. J. Hort. Sci. Technol. 2021 8(3): 227-233
228
apple trees in certain areas of Central Asia.
There, apple trees are grown under dry and hot
summer conditions. However, in winter,
temperatures often fall far below freezing and
there is a significant amount of snowfall-
generated moisture (Hu et al., 2016). In these
areas, water availability and its efficient use
after planting are critical factors for favorable
tree growth. Therefore, to determine optimal
planting time and the best tree management
practices,
understanding
the
physical
development of newly-planted trees is essential.
Most commercially grown nursery trees
have weak root systems and show pruning
damage, which affects shoot growth. Previous
studies have reported that a healthy root
system promotes shoot growth, i.e., the
number of shoots and the height of trees in
one-year-old apple trees (Arakawa et al.,
2014), as well as root growth and shoot
growth in citrus trees (Bevington et al., 1985).
Budiarto et al. (2019) described the potential
benefits of citrus root pruning to manage plant
growth. Arakawa et al. (2014) reported the
impact of winter and fall planting on root
growth and the impact of the roots on shoot
growth. In contrast to spring-planted apple
trees, whose shoots start to grow less than one
month after planting, the buds do not start to
grow on winter-planted trees until after shoot
growth because of the dormancy that caused
by the cold weather conditions. If planted in
the spring, root growth is delayed until after
shoot growth, which commences one month
after planting.
The rootstocks onto which the young trees
are grafted are also important for the
development of the young trees after they are
planted. Soejima et al. (1998) reported that
Marubakaido (Ma) (
M. prunifolia
Borkh.
var.
Ringo
Asami), a semi-vigorous rootstock for
apple trees, is used in most of the apple
orchards in Japan. The advantages of semi-
vigorous Ma are its perfect anchorage, early
and heavy production, resistance to burr root,
crown rot, wooly aphids, tolerance to wet soil
conditions, and ease of propagation with
hardwood cuttings. There is no detailed
research or experiments that have been
conducted regarding root growth that is
related to the physiological changes in apple
trees planted in early winter.
Therefore, the aim of this study was to
investigate the root growth in one-year-old
‘Miyabi Fuji’ and the impact of the physical
growing environment, compare to the semi-
vigorous Marubakaido (Ma) (
Malus prunifolia
'Ringo') with dwarfing M.9 rootstocks under
cold winter conditions. The planting season
and the environmental conditions after
planting affect root growth, shoot growth and
tree architecture. The results showed that root
growth occurred from March, with significant
differences in the two rootstocks.
Materials and Methods
Plant materials and experiment design
One-year-old 'Miyabi Fuji' (a bud sport of 'Fuji'
having good fruit coloration) apple trees,
grafted onto Ma and M.9 rootstocks, were
planted on November 25, 2019. They were then
observed over the winter and during the spring
growing season. The experiment design was as
follows: five measuring dates (January 27,
February 27, March 27, April 27, May 28), two
rootstocks (Ma and M.9), and 15 young trees
planted on each of the two rootstocks. All 30
trees were purchased from "HARADA NURSERY
Co., Ltd, Japan and the experiments were
conducted on the campus of Hirosaki
University. Before planting, all apple saplings
were scaled to the same size by cutting them to
70 cm; roots were pruned to 10 cm (Fig. 1A, B).
On November 25, the young apple trees
were placed in 11 L black plastic nursery pots
that contained a mixture of one-part potting soil
used for trees and two parts black volcanic soil.
These were then placed in a specially designed
hole (Fig. 1C) that would prevent them from
freezing during the winter. In mid-April, the
potted trees were placed above ground.
Alisher Botirov & Osamu Arakawa
Int. J. Hort. Sci. Technol. 2021 8(3): 227-233
229
Daily temperature alterations are shown for
the period of the experiment in Figure 2. The
average monthly temperatures and total
precipitation for the period during which the
experiment was conducted is also shown in
Figure 2. In December, the average monthly
temperature was 1.7 °C and precipitation was
145.5 mm. In January, the average
temperature was 0.3 °C and the precipitation
101 mm. In February, the average temperature
was 0.5 °C and precipitation was 144.5 mm. In
March, the average temperature was increased
to 4.9 °C, while the precipitation was dropped
to 84.5 mm. In April, the average monthly
temperature was increased to 7.5°C and
precipitation was elevated slightly to 98 mm.
Finally, in May, the average temperature was
15 °C and total precipitation was 54 mm.
Fig. 1.
One-year-old ‘Miyabi Fuji’ before and after planting; (A) semi-vigorous Ma; (B) dwarfing M.9; (C)
specially designed hole to prevent winter freezing
Fig. 2.
Daily, maximum, minimum temperatures and total precipitation in Hirosaki, Japan during the experiment period.
Studied traits
On January 27, 2020, the first measurements
were done and were repeated on the 27
th
of
each ensuing month until May 28. The young
trees were removed from their pots each time
before taking the measurements. The roots
were separated from the soil and washed, and
their average length was measured with a
caliper. The tree samples were classified into
the following parts: trunks, rootstock stems,
and roots. All of the parts were weighed, and
then dried in an oven at 80 °C for 48 to 60 hr.
After being dried, all samples were again
weighed and measured for moisture content
(MC). MC was determined using the following
equation (1) where FW is the fresh weight of
the sample and DW is the dried weight of the
sample (Turner, 1981):
A
B
C
Alisher Botirov & Osamu Arakawa
Int. J. Hort. Sci. Technol. 2021 8(3): 227-233
230
100
basis
FW
FW
DW
MC
FW
(1)
Data analysis
The observations regarding the effects on MC
were analyzed by one-way ANOVA (the
difference between dates) and a Tukey test.
Moreover, the effect of rootstocks and dates
were analyzed by a two-way ANOVA. New
shoot length was analyzed using the Student's
t-test. All of the above analyses were
performed using the R studio version 1.3.1073
(© 2009-2020 RStudio, PBC) software.
Results
Root growth
Root growth change was examined between
January and May 2020 for the ‘Miyabi Fuji’ trees
that were grafted onto the Ma and M.9
rootstocks (Table 1). Observations on January 27
and February 27 did not show any root growth
for either rootstocks. On March 27, only root
hairs and root caps less than or equal to two cm
were observed. On April 27, these root hairs and
root caps were grown in length to 10 cm or
more. Then, on May 28, primary, secondary, and
tertiary roots showed vigorous growth.
Table 1.
Root growth for ‘Miyabi Fuji’ on semi-vigorous Marubakaido (Ma) (
Malus prunifolia
'Ringo') and
dwarfing M.9 rootstocks in January through May, 2020
Months
Root growth starting (cm)
a
Parts of the root
b
Ma
M.9
January 27
NG
NG
All
February 27
NG
NG
All
March 27
≤ 2
≤ 2
Root cap
April 27
≤ 10
≤ 10
Root cap
May 28
≥ 10
≥ 10
All
Note: a-average length of new root growth, b-the new root growth occurred by the root area, NG-not growth. All-
primary, secondary, tertiary root and root region.
Moisture content changes in separate
parts of the trees
The changes in moisture content in the trunk
and the results of the ANOVA are shown in
Table 2. The moisture content of the trunks
was increased significantly from January to
May for the trees on both rootstocks. There
was, however, a statistical difference between
the two rootstocks; the MC of M.9 was higher
than that of Ma (P
0.01). The percentage
change in MC for Ma in May was higher than
that recorded in January, February, and
March. The MC for the trunk on dwarfing M.9
increased significantly from January to April
and May. There was no significant difference
statistically between the interrelation of
rootstocks and the months in which they were
measured for trunk MC.
Table 2.
Changes in trunk moisture content for ‘Miyabi Fuji’ on semi-vigorous Marubakaido (Ma) (
Malus
prunifolia
'Ringo') and dwarfing M.9 rootstocks in January through May, 2020
Rootstocks
Moisture content (%)
January
February
March
April
May
Ma
50.9 ± 0.52a
49.7 ± 0.43a
50.3 ± 0.78a
53.1 ± 0.2ab
55.8 ± 1.4b
M.9
51.8 ± 0.15a
52.1 ± 0.03ab 52.1 ± 0.05ab
53.0 ± 0.3b
56.1 ± 0.4c
P value
Significance
Rootstock (R)
0.008026
**
Date (D)
9.297e-08
***
R x D
0.239132
ns
Note: Means ± standard error and different letters indicate statistically significant differences among the months
according to the Tukey test; (*) – P
0.05, (**) – P
0.01, (***) – P
0.001, (ns) – not significance, (n=3).
Alisher Botirov & Osamu Arakawa
Int. J. Hort. Sci. Technol. 2021 8(3): 227-233
231
Rootstock stem MC changes and the
results of ANOVA are shown in Table 3. The
MC of the rootstock stem increased from
January to May on both rootstocks, and
changes in rootstock stem MC was markedly
in different months during the experiment
period. There was a statistically significant
difference between the rootstocks; the MC of
the M.9 rootstock stems was higher than that
of Ma (P
0.0001). The Ma MC decreased
markedly from January to February, then
increased dramatically in March and April,
and increased even more in May. Alteration
of MC for M.9 was notably higher in May
when compared to the earlier months. There
was no statistically significant difference
between the effects of rootstock and the date
for rootstock stem MC.
The changes in MC in the root and the
results of ANOVA are shown in Table 4. The
MC in the roots underwent considerable
changes during the experiment period; MC
increased from January to May for both
rootstock trees. There was statistical
significance in the effects of the rootstocks.
The root MC of M.9 was higher than that of
Ma (P
0.05). The root MC of M.9 increased
significantly from January and February to
March and even more in April, then from April
to May it decreased greatly. There was no
significant difference between the interaction
of rootstock and the date for the root MC.
Table 3.
Changes in rootstock stem moisture content for ‘Miyabi Fuji’ on semi-vigorous Marubakaido (Ma)
(
Malus prunifolia
'Ringo') and dwarfing M.9 rootstocks in January through May, 2020
Rootstocks
Moisture content (%)
January
February
March
April
May
Ma
47.7 ± 0.1b
46.0 ± 0.3a
47.6 ± 0.4b
48.7 ± 0.5b
51.4 ± 0.19c
M.9
48.2 ± 0.6a
48.6 ± 0.4a
48.7 ± 0.6a
50.1 ± 0.7a
52.7 ± 0.34b
P value
Significance
Rootstock (R)
0.0001374
***
Date (D)
1.281e-08
***
R x D
0.2879832
ns
Note: Means ± standard error and different letters indicate statistically significant differences among the months
according to the Tukey test; (*) – P
0.05, (**) – P
0.01, (***) – P
0.001, (ns) – not significance, (n=3).
Table 4.
Changes in root moisture content for ‘Miyabi Fuji’ on semi-vigorous Marubakaido (Ma) (
Malus
prunifolia
'Ringo') and dwarfing M.9 rootstocks in January through May, 2020
New shoot growth for 'Miyabi Fuji'
trees on Ma and M.9
New shoot growth in the trees and results of the
T-test are shown in Figure 3. The new shoots on
the trees were significantly different for the Ma
and M.9 rootstocks, and the growth of new
shoots commenced in May for both Ma and M.9.
There was a statistical difference among the
rootstocks; the total number of new shoots for
Ma was higher than those for M.9 (P
0.05).
Rootstocks
Moisture content (%)
January
February
March
April
May
Ma
55.0 ± 3.3a
54.1 ± 1.4a
60.6 ± 1.1a
61.0 ± 1.6a
56.3 ± 5.4a
M.9
55.3 ± 19.4a
56.8 ± 11.3a
65.8 ± 9.2bc
67.4 ± 7.7c
58.7 ± 7.5ab
P value
Significance
Rootstock (R)
0.044436
*
Date (D)
0.002475
**
R × D
0.759174
ns
Note: Means ± standard error and different letters indicate statistically significant differences among the months
according to the Tukey test; (*) – P
0.05, (**) – P
0.01, (***) – P
0.001, (ns) – not significance, (n=3).
Alisher Botirov & Osamu Arakawa
Int. J. Hort. Sci. Technol. 2021 8(3): 227-233
232
Fig. 3.
Total new shoot length for ‘Miyabi Fuji’ on semi-vigorous Marubakaido (Ma) (
Malus prunifolia
'Ringo')
and dwarfing M.9 on May 28, 2020. Columns shows means ± standard error and different letters indicate
statistically significant differences among the rootstocks according to a T-test P
0.05, (n=3)
Discussion
In cold weather areas, nursery apple trees are
usually planted in the early winter months,
just before snowfall. However, there is no
detailed research or experiments that have
been conducted regarding root growth related
to the physiological changes in apple trees
planted in early winter. Our findings proved
that no root growth occurred in the winter
time, January to February. The roots started to
grow slowly from March to April, whereas in
May vigorous root growth was observed. Van
et al. (2011) reported that root growth for
dwarfing M.9 occurred from December (early
spring time in New Zealand), although they
did not check or mention winter time root
growth. Temperature change is also vital for
root growth. During the experiment period,
the average daily temperature in March was
4.9 °C, which impacted root growth.
Lopushinsky and Max (1990) found that, for
forest trees, root growth occurs when soil
temperature is 5 °C or above.
We measured the MC changes in the below
and above parts of the trees to determine the
relationship between the root condition and
growth of different parts of the tree. The MC of
the trunk increased slowly from January to
May. Root MC increased from January to April
when the new roots appeared. These findings
suggest that these MC changes are related to
root growth and root activity (water
absorption by root). Increase of trunk and
rootstock stem MC may be related to cold-
related damage in young trees during the
spring, since it has been suggested that the
cold hardiness of woody plants is related to
water relations parameters (Anisko and
Lindstrom, 1996).
In our study, root MC decreased when
shoot growth occurred in May on the young
apple trees. Diminishing root MC did not affect
root growth in May and the growing process of
the root went on vigorously. We found that
budburst occurred at the end of April (data not
shown), while total new shoot length was
observed at the end of May (Fig. 3). This
suggests that, in May, the development of
shoots on trees grafted onto semi-vigorous
rootstock take longer than those on dwarfing
M.9. Bevington and Castle (1985) reported
that root growth declined during shoot
elongation for citrus trees when there is no soil
temperature or WC issues.
It is essential to manage soil and water to
promote root growth even after planting. It
appears that both rootstock selection and
winter planting are essential for root growth
when young apple trees are planted in areas
where moisture is provided by snowfall in the
Alisher Botirov & Osamu Arakawa
Int. J. Hort. Sci. Technol. 2021 8(3): 227-233
233
winter but suffer from a shortage of water
during the non-winter months.
Conclusion
This research study investigated the effects of
winter planting on root growth and certain
physical features of one-year old ‘Miyabi Fuji’
apple trees during the winter and spring. We
found that winter planting affected root growth
and that the MC of the trees changed from
February to March. Accordingly, significant
physical changes were observed in the trees.
Hence, winter planting in areas with
limited water-resources would ensure that
there would be sufficient soil moisture to
support root growth and encourage budbreak.
Therefore, in the future, we intend to extend
the scope of our research to water-challenged
areas. The obtained finding of present study
provide insights for apple growers in such
areas regarding the most effective planting
times and the impact of planting time on shoot
growth and growth of the upper and lower
parts of young trees.
Conflicts of Interest:
The authors indicate
no conflict of interest for this work.
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