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EFFECT OF PRUNING DATE ON COLD HARDINESS AND MOISTURE
CONTENT OF 'CONCORD' (VITIS LABRUSCANA BAILEY)

 

BUD AND CANE TISSUES

By

James Alan Woipert

A THESIS

Submitted to
Michigan State University
in partial fulfiTTment of the requirements
for the degree of

MASTER OF SCIENCE

Department of Horticuiture

1978

ABSTRACT
EFFECT OF PRUNING DATE ON COLD HARDINESS AND MOISTURE

CONTENT OF 'CONCORD' (VITIS LABRUSCANA BAILEY)
BUD AND CANE IISSUES

By

James Alan Noipert

'Concord' grapevines (Vitis Tabruscana Baiiey) were pruned on

 

various dates throughout two dormant seasons, 1974-75 and 1975-76.
Coid hardiness and tissue moisture content were measured on each date
to determine if time of pruning affected hardiness, and, if so, if
differences were reiated to tissue moisture content. For primary

and secondary bud tissues and one-year-oid cane tissues, hardiness

was greatest and moisture content least in midwinter (Jan). Hardiness
decreased and moisture content increased during Tate winter and spring.
Bud tissues of vines pruned earIy in the dormant season (Dec) tended
to be Tess hardy than those of vines pruned late in the dormant season
(Mar). Cane tissues showed no hardiness response to pruning date.
Early-pruned vines suffered more spring frost damage than Tate-pruned
vines. Efforts to reiate differences in bud hardiness as a function

of pruning date to changes in moisture content were inconciusive.

To Angie, for her love and understanding.

ii

ACKNOWLEDGEMENTS

I would like to express my sincere thanks to Stan Howell for
his guidance, encouragement and friendship, the effects of which
will be felt for the rest of my career.
I would also like to thank Drs. C. Robert Olien and Frank Dennis

for their thoughtful criticism of the research and manuscript.

iii

TABLE OF CONTENTS

Page
LIST OF TABLES . ......... . . ...... . . . . . . . v
INTRODUCTION . ...... . . . . . . . . . . . . . . . . . . . 1
LITERATURE REVIEW. . . ............... . ..... 1
Pruning and Winter Injury . . . . ..... . . . . . . . . 1
Tissue Water and Plant Hardiness ............. 3
MATERIALS AND METHODS. . . . . . . . . . . . . . ........ 7
Experiment 1 - Effect of pruning date on hardiness and
moisture content, 1974- 75. . ....... . . . . . 7
Experiment 2 - Effect of pruning date on hardiness and
moisture content, and field freeze injury, 1975- 76 . . . 7
Experiment 3 - Effect of sampling date on hardiness and
moisture content of non-pruned vines, 1975-76. . . . . . 8
Experiment 4 - Effect of node position on moisture content. 8
Sampling procedure. . . . . . . . . . . . . . . . . . . . . 8
Cold hardiness evaluation . . . . . . . . . . . . . . . . . 9
Tissue moisture evaluation. . . . . . . . . . . . ..... 9
RESULTS. . . . . . . . . . . ... . . . . . . .......... 11

Experiments 1 and 2 - Effects of pruning date on hardiness

and moisture content, 1974-75 and 1975-76, and field

freeze injury, 1976. . . . . . . . . . . . . . . . . . . 11
Experiment 3 - Effect of sampling date on hardiness and

moisture content of non-pruned vines, 1975-76. . . . . . 13
Experiment 4 - Effect of node position on moisture content. 14

DISCUSSION . . ................. . ....... 15
LITERATURE CITED . . . . . . . . . . . . . . . . . . . . . . . . 32
General References. . . . . . . . . . . . . . . . . . . . . 35

APPENDIX ............................ 36

iv

LIST OF TABLES
Table Page

1 Effect of pruning date on hardiness (percent kill, %K)
and moisture content of primary buds of 'Concord'
QTBPEVTHES, 1974-75. 0 o o o o o o o o o o o o o o o o o 18

2 Effect of pruning date on hardiness (percent kill, %K)
and moisture content of secondary buds of 'Concord'
grapeVineS, 1974'75. o o o o o o o o o o o o o o o o o o 19

3 Effect of pruning date on hardiness (percent kill, %K)
and moisture content of canes of 'Concord'
QI‘BPEVTHES, 1974-75. 0 o o o o o o o o o o o o o o o o o 20

4 Main effect of pruning date on hardiness of 'Concord'
grape buds and canes in Experiment 2, 1975-76. . . . . . 21

5 Main effect of tissues on hardiness of 'Concord' grape
buds and canes in Experiment 2, 1975-76. . . . . . . . . 22

6 Effect of pruning date on hardiness (percent kill, %K)
and moisture content of primary buds of 'Concord'
grapevines, 1975-76. . . . . . . . . . . . . . . . . . . 23

7 Effect of pruning date on hardiness (percent kill, %K)
and moisture content of secondary buds of 'Concord'
grapevines, 1975-76. . . . . . . . . . . . . . . . . . . 24

8 Effect of pruning date on hardiness (percent kill, %K)
and moisture content of canes of 'Concord'
grapeVines, 1975-76. 0 o o o o o o o o o o o o o o o o o 25

9 Hardiness (T50) and moisture content of buds and canes
of 'Concord' grapevines sampled on various dates
throughout the dormant season, 1975-76, in Lawton, Mi. . 26

10 Correlation coefficients for moisture content vs.
hardiness (T50) for Experiment 3, 1975-76. . . . . . . . 27

11 Moisture content of buds and canes of 'Concord' grapevines
on 17 April, 1976 as affected by node position . . . . . 28

12 Analysis of variance of effects of node position on
moisture content of buds and canes of 'Concord'
grapevines . . . . . . . . . . . . . . . . . . . . . . . 29

Table

13

14

A1

A3

A4

A5

A6

A7

A8

A9

A10

A11

A12

Effect of pruning date and node position on the cane on

percent of buds killed by freeze on 26 April, 1976. . . .

Effect of pruning date in 1975-76 on percent swelling on

16 or 18 May following a freeze on 26 April .......

Number
for

Number
for

Number
for

Number
for

Number
for

Number
for

Number
for

Number
for

Number
for

Nunber
for

Number
for

of buds and
sample date

of buds and
sample date

of buds and
sample date

of buds and
sample date

of buds and
sample date

of buds and
sample date

of buds and
sample date

of buds and
sample date

of buds and
sample date

of buds and
sample date

of buds and
sample date

canes
1, 14

canes
2, 13

canes
3, 27

canes
4, 27

canes
5, 17

canes

killed at
Jan, 1975

killed at
Feb, 1975

killed at

Feb, 1975 .

killed at
Mar, 1975

killed at
Apr, 1975

killed at

6, 8 May, 1975.

canes

1, 5 Dec, 1975 ..... . ........

canes

killed at

killed at

2, 8 Jan, 1976.

canes
3, 13

canes
4, 29

canes
5, 30

Daily temperature maxima
at the Michigan State

Research Farm . . . . .

killed at
Feb, 1976

killed at
Feb, 1976

killed at

all

all

all

all

test temperatures

test temperatures

test temperatures

test temperatures

test temperatures

test temperatures

test temperatures

Mar, 1976 . . . . . . . . . . .

and minima (0C) for spring 1976
University Horticultural

vi

Page

30

31

36

37

38

39

4O

41

42

43

INTRODUCTION

Standard recomnendations for grapevines in northern states call for
delaying pruning until late winter (Edgerton and Shaulis, 1953) to allow
selection of fruiting wood which has overwintered in good condition and
adjustment of bud numbers to accommodate losses due to cold. However,
Michigan grape growers frequently begin pruning in late fall and con-
tinue through late spring in order to completely prune their acreage.

I wished to determine if vines pruned early in the dormant season
responded differently to low temperatures than unpruned vines and, if

differences existed, to assess their magnitude and physiological bases.

LITERATURE REVIEW

Pruning and Winter Injury, Several researchers have observed a

 

relationship between pruning and winter damage. Burkholder (1936)
reported that 'Jonathan' and 'Stayman' apple trees suffered substantial
damage when pruned prior to several days of sub-zero temperatures,
whereas unpruned trees showed no injury. He also noted that damage
appeared proportional to the severity of pruning and was cultivar
dependent. Anthony‘gt;31, (1936) also observed a positive correlation
between early pruning and winter injury in Pennsylvania apple orchards.
0n the other hand, Magoon and Dix (1941) found no effect of pruning date

on the yield of several grape varieties in Maryland. In spite of this,

2

the authors implictly acknowledged a possible relationship between
pruning and low temperature stress by concluding that growers in colder
areas would be advised "to wait until the danger of heavy freezing is
past before beginning the pruning work." They also found no difference
in foliation date as a function of pruning date. This contradicts the
work of Loomis (1939) who reported that late pruning delayed foliation
of the grape cultivar Extra in Mississippi.

Edgerton and Shaulis (1953) used artificial freezing methods to test
the effect of fall pruning on the cold hardiness of ‘Concord' grape-
vines. In March unpruned controls were hardier than pruned vines, and
apical segments were less hardy than basal segments of canes from pruned
vines. They also noted that primary bud mortality was greatest near
the tips of canes from pruned vines. Rollins gt_al. (1962) found that
the hardiness of twigs from 'Yellow Transparent' apple trees pruned in
January decreased by 2.5°C within seven hours after pruning. After one
day, pruned trees were 6° less hardy than controls, but after 44 days
they had become more hardy than the controls.

All these reports agree that pruning increases the likelihood
of low temperature injury. The only proposed hypothesis (Rollins g5;gl,,
1962) postulated that the difference in hardiness between pruned and
unpruned trees was due to water from the roots. Because the roots
supply a constant volume of water, the increase in tissue water would
be greater in pruned trees because their reduced tissue volume. This
hypothesis merits investigation in grapevines because pruning by the
balanced-pruning concept of Partridge (1925) results in removal of a

large volume of tissue.

Tissue Water and Plant Hardiness. The relationship between tissue
moisture and hardiness has been investigated for many years. Levitt
(1941) did an excellent job of reviewing the early literature. Traub
(1927) found that apple twigs declined suddenly in percent moisture con-
tent in mid-September whén the leaves were still green. This occurred
in spite of sufficient rainfall. Moisture content rose again in early
April before significant rainfall occurred. Wilner (1952) reported that
cultural treatments had no effect on the water content of mature twigs
of woody plants, and suggested that water content at maturity was gene-
tically determined. Other workers reported low winter moisture values
followed by a spring increase in peach buds (Johnston, 1923) and apple
twigs (Hildreth, 1926; Stark, 1936). Stark (1936) suggested that water
relationships of tip and basal portions of the same apple shoot were
different. Wiegand (1906) found that hardiness in buds of various fruit
trees and ornamentals was related to bud cell size and water content.
Buds with large cell size and high water content were less hardy than
buds with small cell size and low water content. At -18°C the fbrmer
contained ice crystals while the latter resisted ice formation.

In Juniperus chinensis L. 'Hetzi', water content decreased during
acclimation while hardiness increased (Pellet and White, 1969). Gusta
and Weiser (1972) found that the greatest reduction in leaf hydration in
boxwood, an evergreen, appeared to occur during periods when hardiness
was increasing rapidly, but that moisture content remained relatively
constant during periods when hardiness fluctuated. McKenzie gt_gl,
(1974) recently showed the following relationships between moisture and
hardiness in goggg§_stolonifera Michx., in which short days induce the

first stage of hardening:

1. In plants held under long days (LD), water content increased
from the base to the apex of twigs. Short day (SD) plants
showed no such gradient.

2. Major water losses occurred at the time of maturation of pith
cells.

3. SD plants had a 1.5-fold decrease in stomatal resistance and a
3.5-fold increase in root resistance conpared to L0 plants.

4. Clones of g, stolonifera varied in their rates of cold accli-

 

mation. In all but one of these, the earlier the decrease in
water occurred the earlier the plants acclimated to low temper-
ature stress.

The authors suggested that the SD promotion of acclimation (Fuchi-
gami gt_al,, 1971) was due to the reduction in water content, because
no plant hardened to -12°C (the magnitudeof the SD response) without
first losing tissue water.

Artifically increasing and decreasing blueberry bud moisture content
respectively decreased and increased cold hardiness (Bittenbender and
Howell, 1975). Li and Weiser (1971) increased the cold hardiness of
dogwood 3 to 12°C when they removed 4 to 10% of the stem water by freeze-
drying, and the increase was proportional to the amount of water removed.
Inmfis gt_al, (1972) explained differences in survival of two species of

Rhododendron on the basis of water percentage alone. When tissue water

 

content of the less hardy R, poukahense (54% of dry weight) was artifi-
cially decreased to the level of hardy 5, cv. Maryann (46%), the hardi-
ness differences were eliminated. Cabbage (Brassica oleracea L. cv.

Dittmar) kept under growth chamber conditions known to induce hardiness

had less tissue moisture than plants held under warm, non-acclimating

5

conditions (Kacperska-Palacz gt_gl., 1969). Rice seeds with a water
content of 15% of dry weight all germinated after immersion in liquid
N2, but with 21% moisture, no gennination occurred (Sakai and Noshiro,
1975).

Water content can affect the nature of the freezing stress and thus
the killing temperature (Olien, 1974; Lumis and Mecklenburg, 1974).
Metcalf gt_al, (1970) found that a small change in crown moisture content
of wheat and barley resulted in a very large difference in survival at
a given temperature. Gullord (1974) reported that differences in leaf
moisture content explained 69-72% of the variation in hardiness among
selected wheat and rye cultivars.

Plants contain a significant amount of "bound" water which does not
freeze (Levitt, 1941; Mazur, 1969). This is associated with macro-
molecular surfaces and differs from bulk water in several properties,
including freezing point (Cooke and Kuntz, 1974). Nuclear magnetic
resonance (NMR) spectroscopy has been used to quantify bound water
(Toledo g5;3§L., 1968; Sussman and Chin, 1966). Cook and Kuntz (1974)
concluded that water exists in hydration shells and remains liquid
more because of suppressed freezing point than because of supercooling.

Changes in the bound water to bulk water ratio have been proposed
as a mechanism of cold hardening (Pellett and White, 1969; Vasil'yev
g§_gl,, 1975) in spite of earlier rejection of this hypothesis (Stark,
1936; Levitt, 1941, 1956). Recently, Gusta gt_gl, (1975) found no
simple relationship between hardiness and bound water content of wheat
cultivars. They concluded that the difference between tender and hardy
cultivars was the ability of the hardier crown to tolerate diminishing

quantities of liquid water.

Recently, deep supercooling has been shown to be a mechanism of ice
avoidance (see Levitt, 1972) in azalea flower buds (Graham, 1971; George
§t_al,, 1974), apple xylem elements (Quamme gt_al,, 1972) and grape buds
and stems (Pierquet gt_al,. 1977). Changes in ability to supercool
during acclimation may involve the reduction or elimination of nucleation
centers for ice formation or development of barriers to nucleation
(Burke gt;31,, 1976). The lower limit of deep supercooling in the homo-
geneous nucleation temperature of water (approx. -40°C) (Rasmussen and

MacKenzie, 1974).

STATEMENT OF PROBLEM

Based on observations in the literature, the problem to be
researched in this thesis can be outlined as follows:
1. To determine if 'Concord' grapevines pruned early in the dormant
season respond differently to low temperature stress than do unpruned
vines.
2. To determine if fluctuations in hardiness due to treatment or time

of year can be explained by changes in tissue moisture content.

MATERIALS AND METHODS

Experiment 1 - Effect of pruning date on hardiness and moisture
content, 1974-75. In mid-winter, 1974-75, an experiment was initiated
at the Michigan State University Horticultural Research Farm using 10-
year-old 'Concord' (Vitis labruscana Bailey) grapevines. Vines were
divided into six treatment groups and each was assigned to one of six
pruning dates (14 Jan., 13 Feb., 27 Feb., 27 Mar., 17 Apr., and 8 May).
Treatments were arranged in a completely randomized design with four
replicates. Each treatment group was balanced pruned by means of a
30+10 fOrmula (i.e., 30 buds retained for the first pound of cane
prunings and 10 buds for each additional pound) and trained to a 4-arm
Kniffen system. On each date canes were collected from the vines pruned
and from all previously pruned vines for determinations of moisture
content and cold hardiness. Thus, on the first pruning date one group
was sampled, while on the sixth date all six treatments were sampled.
The number of buds required for sampling was calculated in advance, and
during pruning these were left in addition to nodes retained by the
pruning formula. Thus, changes in bud and cane hardiness and moisture
content could be followed subsequent to pruning and compared with that
of control (unpruned) vines.

Experiment 2 - Effect ofgpruning date on hardiness and moisture

content, and field freeze injury, 1975-76. In winter 1975-76 the experi-

 

mental area was increased to include a block of four-year-old vines on

7

the same site. A randomized block design was used to partition out
varability due to vine age. Five pruning dates were used (5 Dec., 8 Jan.,
13 Feb., 29 Feb., and 30 Mar.), vines being sampled as in Experiment 1.
Warm air temperatures in early and mid-April (Table A12) resulted
in rapid bud development. A severe freeze (-4°C) on 26 April caused
extensive damage to swelling buds. Canes bearing 12 to 16 nodes were
examined on 16 and 18 May to determine whether the extent of injury was
related to pruning date. Observations included 1) the number of buds
which swelled prior to the freeze and were subsequently killed, and
2) the number of buds swelling at the time of observation. Data were
taken on 6 to 10 nodes per replicate.
Experiment 3 - Effect of sampling_date on hardiness and moisture

content of non-pruned vines, 1975-76. The experimental design for

 

Experiments 1 and 2 allowed for comparisons only within sampling dates.
Experiment 3 was initiated at the Rogers Concord vineyard in Lawton,
Michigan to provide information on the relationship between tissue
moisture and cold hardiness from late fall to early spring. The vines
had been balanced pruned fOr five previous years but were not pruned
during the sampling period.

Experiment 4 - Effect of node_position on moisture content. On 11
April, 1976 canes 14 to 18 nodes in length were gathered from unpruned
Concord grapevines at the MSU Horticultural Research Farm. Node numbers
2, 4, 6, 8, 10, and 12 were collected individually. Tissue moisture
content was determined as a function of node position.

Sampling_procedure. In all experiments sample material consisted
ofone-year-old, well-exposed, mature cone pieces (10-12cm) of unifonn

diameter (6-7mm) with one bud located in the middle. Exposure and

maturity were assessed visually and only canes with reddish-brown periderm
were used. Samples were divided into two lots for separate determina-
tions of cold hardiness and moisture content of buds and canes.

Cold hardiness evaluation. Freezing technique for canes and buds
was essentially that used by Howell and Weiser (1970) as modified by
Stergios and Howell (1973). Cane sections were inserted into vacuum
flasks and placed in a Revco chest freezer. The temperature was reduced
at a consistent rate (3-50C/hr in side the flasks). Cane temperatures
were monitored with a 24-gauge c0pper-constantan thermocouple inserted
into the pith of a representative cane in each flask. Test temperatures
varied with the time of year and expected hardiness of the material. A
control (unfrozen) sample was included for each treatment to estimate
field mortality. A temperature range was chosen such that the warmest
temperature produced no injury and the coldest was lethal for all tissues.
At regular temperature intervals flasks were removed and allowed to
warm to room temperature overnight. Canes were then placed in a humid
chamber for 7-10 days to allow injured tissues to turn brown (Stergios
and Howell, 1973) after which they were sectioned transversely with a
razor blade, observed through a binocular microscope, and rated as alive
or dead. Buds were considered dead when any part of the primordium was
brown, while twigs were arbitrarily recorded as dead when more than half
of the phloem-cambium area was brown.

Tissue moisture evaluation. For Experiment 1 primary and secondary
buds were excised, separated and weighed singly on a Mettler H31 single-
pan balance. Tertiary buds were excluded because their small size
precluded accurate measurement on the Mettler balance. Cane segments

(2-4cm), cut from the middle of the sample piece, but just proximal to

10

the node, were used for cane moisture measurements. All tissues were
oven-dried overnight at 70°C and reweighed. From these data the amount
of water was calculated by difference and expressed as grams of water
per gram of tissue dry weight.

The moisture content procedure for Experiment 2 was changed because
the data for the previous year were very variable (coeff. var. = 15-30%).
Bud tissues weighed directly on the balance gained and lost moisture
too quickly, especially when they were dried. 0n the suggestion of
Olien (personal communication), three primary and secondary buds per
replicate were excised, separated and placed in air-tight glass vials
(7.5 x 15mm) with ground-glass stoppers. These containers greatly
reduced water loss during weighing and decreased variation (coeff. var =
2-10%). Three cane sections per replicate were weighed together directly
on the balance with acceptable results. All tissues were oven-dried fbr
36 hours at 70°C and vial weights were taken after drying.

The only difference in procedure for Experiment 3 was that three
cane peices per replicate were placed in large glass vials (25 x 50mm)
with ground-glass stoppers. Bud tissues were handled as in Experiment 2.
The moisture content procedure for Experiment 4 was identical with that

for Experiment 2.

RESULTS

Experiments 1 and 2 - Effects of pruning date on hardiness and
moisture content,_1974-75 and 1975-76,_and field freeze injury, 1976.
Complete data for the hardiness portion of both experiments are
presented in the Appendix, Tables A1-A11. Hardiness values for Experi-
ment 1 were averaged over several test temperatures and are presented
as percent kill in Tables 1-3 for primary buds, secondary buds and canes,
respectively. Data were not analyzed statistically because of the small
number of observations (4) per temperature, but some trends were evident.

Tertiary bud hardiness data for individual dates appear only in
the Appendix for several reasons: 1) tertiary buds produce little crop,
even in years when primary and secondary buds are killed; 2) they
present no physiological information which differs from that of other
tissues; 3) no moisture content data are available for comparison.

Primary buds of vines pruned early in the dormant season tended to
be less hardy than those pruned late in the dormant season (Table 1).
The same is true of secondary buds (Table 2) and canes (Table 3) but to
a lesser extent. The data also suggest that vines pruned on the sample
date (i.e., treatment 2 on date 2 through treatment 6 on date 6) tended
to be less hardy than vines pruned 2 to 4 weeks earlier. This effect
can also be seen for secondary buds and canes.

Differences in moisture content of primary buds (Table 1) were not

statistically significant until the last two sampling dates. On 17 April.

11

12
1975, the highest primary bud moisture content was associated with the
greatest percent kill (treatment 1). However, among the remaining
treatments, percent kill ranged from 0 to 42 percent while moisture con-
tent did not differ. For 8 May, the reverse was true, the greatest
percent kill being associated with the lowest moisture content.

Hardiness data for Experiment 2 are presented both in main effects
tables (Tables 4 and 5) and together with tissue moisture content in
Tables 6-8. Percent kill values were combined across replicates and
statistically analyzed with test temperatures as blocks.

Unfrozen controls for each treatment provided an estimate of per-
cent field kill. Values were corrected by subtraction of field injury.
Experimental values which were less than values for field injury were
assumed to be zero. All corrected percent kill values were transformed
by arcsine transformation (Bartlett, 1947) prior to statistical analysis,
and significant differences were determined with transformed data.

Vines pruned early in the dormant season suffered more injury than
those pruned later (Table 4). Generally, hardiness differences between
tissues (Table 5) were not as marked as previously reported (Stergios
and Howell, 1976; Pogosyan and Sarkaisova, 1967; Pierquet gt_al,, 1977).
For primary buds, differences in percent kill were significant on only
two dates (13 Feb. and 30 Mar.), and in both cases the vines pruned
earlier were less hardy than those pruned later (Table 6). The 29 Feb.
sample date showed the same trend although the values were not statis-
tically significant.

Pruning date had no significant effect on hardiness of secondary
buds and hardiness of canes was affected only on 30 Mar., the earliest

pruned vines showing the greatest injury (Tables 7 and 8). In contrast

13

with the data obtained in Experiment 1, vines sampled at the time of
pruning were never significantly less hardy than other treatments.

Moisture content in Experiment 2 was not related to tissue hardi-
ness (Table 6-8).

Generally, spring freeze injury to both primary and secondary buds
was greater near the distal end than near the basal end of the cane
(Table 13), but differences were significant in only one case for each
tissue. There was no effect of pruning date on injury to primary buds.
In secondary buds pruning tended to increase injury but only for nodes
7-9 was the effect significant. After the freeze a greater percentage
of primary and secondary buds were alive near the base of the canes and
pruning tended to decrease the number of live buds (Table 14).

Experiment 3 - Effect of sampling date on hardiness and moisture
content of non-pruned vines,,1975-76. Data for Experiment 3 are
expressed as T50 (the theoretical temperature at which 50% of the tissues
die) calculated by means of the Spearman-Karber equation as modified by
Bittenbender and Howell (1975). The T50 is an absolute hardiness
measure which allows comparison across dates.

Maximum hardiness for all tissues was achieved in mid-winter
(Table 9). Primary buds appeared to harden slower and deharden faster
than either secondary buds or canes. Canes were hardier than buds in
mid-winter and secondary buds were hardier than primary buds. In early
March the hardiness difference among tissues disappeared, but canes were
again hardier than bud tissues in April.

For the first four sample dates, canes contained significantly
more water than bud tissues. For the next three sample dates differences

among tissues were nonsignificant. 0n the last sample date moisture

14

content differed significantly in all three tissues; primary buds con-
tained the most water and canes the least. Water content declined
from December to early February in all tissues, then rose during the
dehardening period (March-April) in bud tissues, with the primary bud
increasing more dramatically than the secondary. Canes showed no such
increase in moisture content through 5 April.

Correlation coefficients relating moisture content vs. hardiness
were significant for bud tissues but not for canes (Table 10).

Experiment 4 - Effect of node position on moisture content. Bud
water content was generally greater at more distal nodes (Table 11) and
buds generally contained more water than cane tissues. Although
analysis of variance indicated no significant effect of node position,

the linear component was significant at 1% (Table 12).

DISCUSSION

Data from Experiments 1 and 2 support the hypothesis that vines
pruned before mid-February are less hardy in the spring than unpruned
vines (Edgerton and Shaulis, 1953), and suggest that the relationship
may be quantitative, i.e., the earlier the pruning date the less the
hardiness. These effects are greatest in the primary bud which is most
productive (Stergios and Howell, 1974) and least hardy (Stergios and
Howell, 1977). Primary buds were injured more by spring frost than secon-
dary buds, and early-pruned vines suffered more damage than late-pruned
vines. No data were taken on foliation date pgr_§g, but observations
in vineyards show that vines which suffered more damage began to develop
early (Byrne, 1976; Howell and Wolpert, unpublished).

The relationship between moisture and hardiness (Table 9) is in
total agreement with the literature (Pellett and White, 1969; Lumis
gt_al,, 1972; McKenzie gt_al,, 1974; Burke gt_al,, 1976). There is an
inverse relationship between the two factors: more moisture/ less hardy
(fall and spring) and less moisture/ more hardy (winter). However, in
instances where pruning date affected hardiness, no concomitant differ-
-ences in moisture content could be found.

Several explanations may be offered for the lack of a close rela-
tionship between moisture content and small changes in hardiness. First,
perhaps moisture content has no effect on hardiness. Hardiness fluctu-

ations may be due to some other factor(s), physical or physiological,

15

16

other than gross water content (Gusta and Weiser, 1972; Bittenbender
and Howell, 1975).

Secondly, variability may have been large enough to mask the
relationship. The experimental area at the Research Farm is a marginal
Concord grape site. Extremely low mid-winter temperatures (-28°C,

18 Jan., 1976, Table 15) killed a large number of buds, which affected
the hardiness evaluation. In addition, error may have been involved in
the sampling procedure. Because of limited plant material in Experi-
ments 1 and 2, whole canes were collected and sections were randomly
allocated to test temperatures. Experiment 4 showed that a gradient
of water does exist from base to apex in a grape cane. This variation
in water content may have affected hardiness, if the water/hardiness
relationship is valid.

Thirdly, during the preparation of twigs for freezing they may have
thawed long enough to alter their hardiness. Pierquet §t_gl,, (1977)
have shown that wild grape (Vjtj§_riparia Michx.) twigs deharden when
thawed for 24 hours; wood exotherm occurs at a warmer temperature and
bud exotherms appear where none were present during freezing of non-
thawed material. The authors speculate that the change is due to water
entering the bud from the thawed cane, but they present no data on bud
water content.

Fourthly, variation may have existed in techniques. The freezing
process within several vacuum flasks may have been different enough
(e.g., amount of supercooling) to affect the percent kill (Olien,
personal conmunication). Also, the method of determining water content
of buds measured gross bud moisture i.e., water content of both the

primordia and fleshy bud scales. Water could have moved between the

17
primordia and bud scales during hardiness fluctuations without any
apparent change in total bud moisture.

Thus, the question: Is water content directly related to small
hardiness fluctuations and differences due to pruning date? has not
been adequately answered. The data presented here neither support
the hypothesis nor refute it. Further research is needed, with emphasis
on eliminating sources of variation, before the question can be
answered.

Several other questions are raised by this research: 1) If the
'pruning date effect is quantitative (i.e., the earlier the pruning
takes place the greater the deleterious effect) as the data suggest,
what changes take place and how does pruning effect them? 2) Why
do primary buds respond more than secondary buds? 3) Why do early-
pruned vines suffer more damage in a spring frost? 4) Why do apical
buds develop earlier than basal buds? Answers to these questions will
not only improve our understanding of vine hardiness physiology, they
will provide a basis for cultural modification of grapevines to reduce

the impact of cold stress.

18

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21

Table 4. Main effect of pruning date on hardiness of 'Concord' grape
buds and canes in Experiment 2, 1975-76. Values are percentage
kill averaged for several test temperatures and all tissues.
Test temperatures varied with time of year so that mean
comparisons can be made only within one sampling date.

 

 

Sampling date

 

Date of

pruning 5 Dec 8 Jan ' 13'Feb ‘29 Feb___ 30 Mar
5 Dec - -2 34ay 26a 38a 49a
8 Jan 30a 14b 32b 43ab
13 Feb 13b 28b 35bc
29 Feb 34ab 36bc
30 Mar 34c

ZNo comparison possible.

yMean separation by Duncan's Multiple Range Test. Within columns, means
followed by the same letter are not significantly different at p=.05.

22

 

 

 

 

Table 5. Main effect of tissues on hardiness of 'Concord' grape buds
and canes in Experiment 2, 1976-76. Values are percentage
kill averaged for several test temperatures and all pruning
dates. Test temperatures varied with time of year so that
mean comparisons can be made only within one sampling date.

Sampling date

Tissue 5 Dec 8 Jan 13 Feb 29 Feb 30 Mar

P rimary 26bz 44a 22a 36a 45a

bud

Secondary 13b 36ab 17a 31a 43a

bud

Tertiary 12b 20b 18a 30a 36b

bud

Cane 77a 28b 13a 35a 33b

 

zMean separation by Duncan's Multiple Range Test.

Within columns, means

followed by the same letter are not significantly different at p=.05.

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23

 

 

 

 

 

 

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27

Table 10. Correlation coefficients for moisture content vs. hardiness
(T50) for Experiment 3, 1975-76.

 

 

 

 

Tissue Correlation coefficient
Primary bud 0.802 **
Secondary bud 0.638 **

Cane 0.048

** Significant at p=.01.

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28

 

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29

Table 12. Analysis of variance of effects of node position on moisture
content of buds and canes of 'Concord' grapevines. (Data
presented in Table 11.)

 

 

§93§£§_ gf_ SS MS F value
Total 53 7737.05 - - - -
Block 2 133.60 66.80 1.40 n.s.
Tissue (T) 2 4877.83 2438.91 51.02 **
Pri + Sec 4797.07 4797.07 100.03 **
vs. Cane
Pri vs. Sec 80.76 80.76 1.69 n.s
Node (N) 5 553.24 110.65 2.31 n.s
Linear 345.90 345.90 7.23 **
Quadratic 7.04 7.04 0.16 n.s
Cubic 4.74 4.74 0.09 n.s
N x T 10 547.33 54.73 1.14 n.s
Error 34 1625.05 47.80 - -

 

30

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31

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LITERATURE CITED

Anthony, R.D., R.H. Sudds and W.S. Clark, Jr. 1936. Low temperature
injury to orchards in Pennsylvania and adjoining states in the
fall and winter of 1935-36. Proc. Amer. Soc. Hort. Sci. 34:33-34.

Bartlett, M.S. 1947. The use of transformations. Biometrics 3:39-52.

 

Bittenbender, H.C. and G.S. Howell, Jr. 1974. Adaptation of the Spear-
man-Karber method for estimating the T 0 of cold-stressed flower
buds. J. Amer. Soc. Hort. Sci. 99:187-190.

. 1975. Interactions of temper-
ature and moTSture content on spring de-acclimation of flower buds
of highbush blueberry. Can. J. Plant Sci. 55:447-452.

 

 

Burke, M.J., L.V. Gusta, H.A. Quamme, C.J. Weiser and P.H. Li. 1976
Freezing and injury in plants. Annu. Rev. Plant Physiol.
27:507-528.

Burkholder, C.L. 1936. December pruning in 1935 results in severe
injury to Jonathan and Stayman trees at Lafayette, Indiana. Proc.
Amer. Soc. Hort. Sci. 34:49-51.

 

Byrne, M.E. 1976. The cultural manipulation of vine vigor as it relates
to the cold hardiness, wine quality, and productivity of Baco noir
grapevines, initial effects. M.S. Thesis. Mich. St. Univ. 106p.

Cooke, R. and I.D. Kuntz. 1974. The properties of water in biological
systems. Annu. Rev. Biophys. Bioengin. 3:95-126.

Edgerton, L.J. and N.J. Shaulis. 1953. The effect of time of pruning
on cold hardiness of Concord grape canes. Proc. Amer. Soc. Hort.
"§gfi, 62:209-213.

Fuchigami, L.H., C.J. Weiser and D.R. Evert. 1971. Induction of cold
acclimation in Cornus stolonifera Michx. Plant Physiol. 47:98-103.

 

 

George, M.F., M.J. Burke and C.J. Weiser. 1974. Supercooling in over-
wintering azalea flower buds.‘ Plant Physiol. 54:29-35.

Graham, R.P. 1971. Cold injury and its determination in selected
‘ Rhododendron species. M.S. Thesis. Univ. Minn. St. Paul, 46p.

 

Gullord, M. 1974. Genetics of freezing hardiness in winter wheat
‘(Triticum aestivum L.). Ph.D. Thesis. Mich. St. Univ. 70p.

32

33

Gusta, L.V., M.J. Burke and A.C. Kapoor. 1975. Determination of
unfrozen water in winter cereals at subfreezing temperatures.
Plant Physiol. 56:707-709.

and C.J. Weiser. 1972. Nucleic acid and protein changes in
relation to cold acclimation and freezing injury of Korean boxwood
leaves. Plant Physiol. 49:91-96.

 

 

Hildreth, A.C. 1926. Determinations of hardiness in apple varieties
and the relation of some factors to cold resistance. Univ. Minn.
Agr. Expt. Sta. Tech. Bul. 42, 37p.

Howell, G.S., Jr. and C.J. Weiser. 1970. Fluctuations in the cold
resistance of apple twigs during spring dehardening. J. Amer. Soc.
Hort. Sci. 95:190-192.

Johnston, E.S. 1923. Moisture relations of peach buds during winter
and spring. Univ. Maryland Agr. Expt. Sta. Bul. no. 255.

Kacperska-Palacz, A., M. Blaziak and B. Wcislinska. 1969. The effect
growth retardants CCC and B-9 on certain factors related to cold
acclimation of plants. Bot. Gaz. 130:213-221.

Levitt, J. 1941. Frost killing and hardiness of plants: A critical
review. Burgess Pub. 60., Minneapolis, Minn. 211p.

. 1972. Responses of plants to environmental stress. Academic
Press, New York. 697p.

Li, P.H. and C.J. Weiser. 1971. Increasing cold resistance of stem
sections of Cornus stolonifera by artificial dehydration.
Cryobiolggy 8:108-111.

 

 

Loomis, N.H. 1939. Note on grape foliation as affected by time of
pruning. Proc. Amer. Soc. Hort. Sci. 37:653-654.

Lumis, G.P. and R.A. Mecklenburg. 1974. Freezing patterns in twigs
of evergreen azalea. J. Amer. Soc. Hort. Sci. 99:564-567.

and K.C. Sink. 1972. Factors
”influencing winter hardiness of flower buds and stems of evergreen
azaleas. J. Amer. Soc. Hort. Sci. 97:124-127.

 

Magoon, C.A. and I.W. Dix. 1941. Relation of time of pruning to per-
formance of grapes. Proc. Amer. Soc. Hort. Sci. 38:369-372.

McKenzie, J.S., C.J. Weiser and P.H. Li. 1974. Changes in water
relations of Cornus stolonifera during acclimation. J. Amer. Soc.
Hort. Sci. 99:223-228.

Metcalf, E.L., C.E. Cress, C.R. Olien and E.H. Everson. 1970. Relation-
ship between crown moisture content and killing temperature for
three wheat and three barley cultivars. Crap Sci. 10:362-365.

34

Olien, C.R. 1967. Freezing stresses and survival. Annu. Rev. Plant
Physiol. 20:387-408.

 

. 1974. Stress analysis. In_Winter hardiness in barley.
pp.*1-10, Mich. St. Univ. Agr. Exp. Sta. Res. Rpt. 247.

 

Partridge, N.L. 1925. The fruiting habits and pruning of the Concord.
grape. Mich. St. Univ. Tech. Bul. no. 69, 39p.

Pellett, N.E. and 0.8. White. 1969. Relationship of seasonal tissue
changes to cold acclimation of Juniperus chinensis 'Hetzi'.
J. Amer. Soc. Hort. Sci. 94:460-462.

 

Pierquet, P., C. Stushnoff and M.J. Burke. 1977. Low temperature
exotherms in stem and bud tissues of Vitis riperia Michx. J. Amer.
Soc. Hort. Sci. 102:54-55.

 

Pogosyan, K.S. and M.M. Sarkaisova. 1967. Frost resistance of grape
varieties in relation to the conditions of hardening. Soviet Plant
Physiol. 14:886-891.

 

Quamme, H., C.J. Weiser and C. Stushnoff. 1973. The mechanism of
freezing injury in xylem of winter apple twigs. Plant Physiol.
51:273-277.

 

Rasmussen, D.H. and A.P. McKenzie. 1972. Effect of solute on ice-
solution interfacial free energys calculation from measured homo-
geneous nucleation temperatures. In Water structure at the water-
polymer interface. pp. 126-145. BTW. Jellenik (ed.) Symp. 16lst.
Nat. Meeting Amer. Chem. Soc., Plenum Press, New York.

Rollins, H.A., Jr., F.S. Howlett and F.H. Emmert. 1962. Factors
affecting apple hardiness and methods of measuring resistance of
tissue to low temperature injury. Ohio Agr. Exp. Sta. Res. Bul 901.
71p.

Sakai, A. and M. Nashiro. 1975. Some factors contributing to the
survival of crop seeds cooled to the temperature of liquid nitrogen.
“In Crop genetic resources for toda and tomorrow. pp. 317-326.
07H. Frankel and J.G. Hawkes (eds. Cambridge Univ. Press.

Stark, A.L. 1936. Unfrozen water in apple shoots as related to their
winter hardiness. Plant Physiol. 11:689-711.

Stergios, B.G. and G.S. Howell, Jr. 1973. Evaluation of viability
tests for cold stressed plants. J. Amer. Soc. Hort. Sci. 98:325-
330.

 

. 1974. In situ destruction of
dbrmant ‘COncordT'grape primary buds withBht secondary bud kill.
HortScience 9:120-122.

 

 

35

Stergios, B.G. and G.S. Howell, Jr. 1973. Effects of defoliation,
trellis height, and cropping stress on the cold hardiness of
Concord grapevines. Amer. J. Enol. Vitic. 28:34-42.

 

Sussman, M.V. and L. Chin. 1966. Liquid water in frozen tissue: study
by nuclear magnetic resonance. Science 151:324-325.

Toledo, R., M.P. Steinberg and A.I. Nelson. 1968. Quantitative
detennination of bound water by NMR. J. Food Sci. 33:315-317.

 

Traub, H.P. 1927. Regional and seasonal distribution of moisture,
carbohydrates, nitrogen and ash in 2-3 year portions of apple twigs.
Univ. Minn. Agr. Expt. Sta. Tech. Bul. 53. 67p.

Vasil'yev, I.M., N.N. Ishmukhametova, H.A. Galiev and V.I. Khismutidinova.
1975. Changes in the state of water in seedlings of winter crops
under the influence of hardening. Soviet Plant Physiol. 22:311-314.

 

Wiegand, K.M. 1906. Some studies regarding the biology of buds and
twigs in winter. Bot. Gaz. 41:373-424.

Wilner, J. 1952. The effects of seasonal and cultural variations on

maturity of woody plants commonly grown on the Canadian prairies.
Sci. Agr. 32:568-573.

General References

 

Steel, R.G.D. and J.H. Torrie. 1960. Principles and procedures of
statistics. McGraw-Hill Co. Inc. New York. 418p.

APPENDIX

36

Table A1. Number of buds and canes killed at all test temperatures
for sample date 1, 14 Jan, 1975. Values are number killed
of four observations, unless otherwise indicated. Only the
data for temperatures with asterisks were used in computations.

 

 

 

Tissue
Test Primary Secondary Tertiary

Pruning date temperature bud bud bud Cane
14 Jan, 1975 Control 2 0 0 0

-15* 1 1 1 0

-20* 0 0 0 0

-25* 4 4 4 4

-30 4 4 4 4

-35 4 4 4 4

 

37

Table A2. Number of buds and canes killed at all test temperatures for
sample date 2, 13 Feb, 1975. Unless otherwise indicated,
values are number killed of four observations. Only the data
for temperatures with asterisks were used in computations.

 

 

 

Tissue
Test Primary Secondary Tertiary
Pruning date temperature bud bud bud Cane
14 Jan, 1975 Control 1 1 1 1
-15* 0 0 1 0
-20* 2 1 1 1
-25* 0 0 0 4
-30* 3 3 3 4
-35 4 4 4 4
13 Feb, 1975 Control 0 0 0 0
-15* 1 1 0 0
-20* 3 2 1 1
-25* 0 1 0 2
-30* 4 4 4 4
-35 4 4 4 4

 

38

Table A3. Number of buds and canes killed at all test temperatures for
sample date 3, 27 Feb,1975. Unless otherwise indicated,
values are number killed of four observations. Only the data
for temperatures with asterisks were used in computations.

 

 

 

Tissue
Test Primary Secondary Tertiary
Pruning date temperature bud bud bud Cane
14 Jan, 1975 Control 1 0 1 1
-15* 1 0 0 0
-20* 3 1 1 3
-25* 4 4 4 3
-30 4 4 4 4
-35 4 4 4 4
13 Feb, 1975 Control 0 0 0 0
-15* 0 0 0 0
-20* 0 1 0 1
-25* 4 2 0 1
-30 4 4 4 4
-35 4 4 4 4
27 Feb, 1975 Control 0 0 0 0
-15* 2 1 1 0
-20* 1 0 0 2
-25* 4 4 4 4
-30 4 4 4 4
-35 4 4 4 4

 

39

Table A4. Number of buds and canes killed at all test temperatures for
sample date 4, 27 Mar, 1975. Unless otherwise indicated,
values are number killed of four observations. Only the data
for temperatures with asterisks were used in computations.

 

Tissue

Test Primary Secondary Tertiary
Pruning date temperature bud bud bud Cane

 

14 Jan, 1975 Control
-10*
-15*
-20*
-25
-30

b-DOOOI—I
##OOOO

13 Feb, 1975 Control
-10*
-15*
-20*

27 Feb, 1975 Control

NN
NN

NN
h-bOOOO th—IOOD «DwNNOO

27 Mar, 1975 Control

-25
-30

kho—IOOO h-bOOOO ##NOu—IN ##OHv—Iw

h-hl—n—IOO h-bOOOO pan-900w:
##HOOO beOOO b-hD-‘Ol-‘I—I

h-bNOOt—I

 

zNumber killed of three observations.

40

Table A5. Number of buds and canes killed at all test temperatures for
sample date 5, 17 Apr, 1975. Unless otherwise indicates,
values are number killed of four observations. Only the data
for temperatures with asterisks were used in computations.

 

Tissue

Test Primary Secondary Tertiary
Pruning date temperature bud bud bud Cane

14 Jan, 1975 Control
-11*
-15*
-17.5*
-20
-25

13 Feb, 1975 Control

N
happy-a0 pawl—ace

27 Feb, 1975 Control

N
N

27 Mar, 1975 Control

N
«b-hi-IHOO bhO—‘OOI—I

17 Apr, 1975 Control

I

H

\l

0"

‘-
k-bNNI—‘O ##OOOO ##l—IOOO h-bNI—H—IO h-thD—DO
##NNHO b-bHOt—DO hoot—'OOO «D-le-IOO h-bwt—‘OO
h-DNNHO ##OOOO «bhl—IOOO h-fi-NOOO b-PwI-‘OO

.h-DNNOI—I

 

zNumber killed of three observations.

41

Table A6. Number of buds and canes killed at all test temperatures for
sample date 6, 8 May, 1975. Unless otherwise indicated,
values are number killed of four observations. Only the data
for temperatures with asterisks were used in computations.

 

Tissue

Test Primary Secondary Tertiary
Pruning date temperature bud bud bud Cane

14 Jan, 1975 Control
0*
-5*
-7.5*
-10*
-15

13 Feb, 1975 Control
0*
-5*
-7.5*
-10*
-15

27 Feb, 1975 Control

27 Mar, 1975 Control
0*
-5*
-7.5*
-10*
-15

17 Apr, 1975 Control

8 May, 1975 Control

huh-coo #000000 #000000 hoot—1000 ##01-400 b-n-Hi—u—IO
#wi—I000 #090000 #000000 43000000 ##0000 h-hI—‘OOO
hoot-1000 «#00000 #000000 4>N0000 ##0000 #030000
hide-I000 hHOOOO 450-400-900 hNOOOO h-hOt—IOO #NNOOO

 

42

Table A7. Number of buds and canes killed at all test temperatures for
sample date 1, 5 Dec, 1975. Values are number killed of
twelve observations unless otherwise indicated. Only the
data for temperatures with asterisks were used in computations.

 

 

 

Tissue
Test Primary Secondary Tertiary

Pruning date temperature bud bud bud Cane
5 Dec, 1975 Control 0 1 0 O

-10* ' O O 0 O

-15* O 0 O 1

-17.5* 1 2 O 9

-20* O O O 7

-25* 8 3 4 12

 

43

Table A8. Number of buds and canes killed at all test temperatures

for sample date 2, 8 Jan, 1976.
of twelve observations unless otherwise indicated.

Values are number killed

Only the

data for temperatures with asterisks were used in compu-

 

 

 

tations.
Tissue
Test Primary Secondary Tertiary
Pruning date temperature bud bud bud Cane
5 Dec, 1975 Control 4z 12 Oz 02
-22.5* 3 O 0 O
-25* 5 2 2 5
-27.5* 12 12 7 9
-31 12 12 12 12
-35 12 12 12 12
8 Jan, 1976 Control 1z 12 1Z o2
-22.5* 4 O O 0
-25* 4 3 2 1
-27.5* 12 11 5 5
-31 12 12 12 9
-35 12 12 12 12

 

zNumber killed of

eleven observations.

 

44

Table A9. Number of buds and canes killed at all test temperatures for
sample date 3, 13 Feb, 1976. Values are number killed of
twelve observations unless otherwise indicated. Only the
data for temperatures with asterisks were used in compu-

 

 

 

tations.
Tissue
Test Primary Secondary Tertiary
Pruning date temperature bud bud bud Cane
5 Dec, 1975 Control 32 3Z oz 0’-
-15* 5 4 2 0
-2o* 5 5 2V 1
-23* 7 4 2 0
-25* 10 9 5 8
-30 12 12 12 12
8 Jan, 1976 Control 12 12 1Z oz
-15* 4 O O O
-20* 4 3 2 1
-23* 12 11 5 5
-25* 12 12 12 9
-3O 12 12 12 12
13 Feb, 1976 Control 5 1 O O
-15* 2 O 0
-2o* 3y 1y 1y 1y
-23* 4 3 1 1
-25* 9 3 4 5
-3O 12 12 12 12

 

ZNumber killed of 10 observations.

yNumber killed of 11 observations.

45

Table A10. Number of buds and canes killed at all test temperatures
for sample date 4, 29 Feb, 1976. Values are number killed
of 24 observations unless otherwise indicated. Only the
data for temperatures with asterisks were used in compu-

 

 

 

tations.
Tissue
Test Primary Secondary Tertiary
Pruning date temperature bud bud bud Cane
5 Dec, 1975 Control 3z 12 oz 02
-15* 12 2 1 2
-20* 8 4 2 4
-25* 22 21 20 22
-3O 24 24 24 24
-35 24 24 24 24
8 Jan, 1976 Control 10y 5i 4y 0y
-15* 8 4 4 2
-20* 9x 7x 5 5
-25* 23 22 23 19
-30 24 24 24 24
-35 24 24 24 24
13 Feb, 1975 Control 7w 6" 2W 11W
-15* 9x 4x 4x 0
—20* 4x 1x 2x 4
-25* 20 18 20 22
-3O 24 24 24 24
-35 24 24 24 24
29 Feb, 1976 Control 9 4 2 O
-15* 5x 0x 0 0
-2o* 12x 7x 3x 1
-25* 24 23 21 19
-3O 24 24 24 24
-35 24 24 24 24

 

 

zNumber killed of 16 observations.
yNumber killed of 19 observations.
xNumber killed of 23 observations.

wNumber killed of 20 observations.

46

Table A11. Number of buds and canes killed at all test temperatures
for sample date 5, 30 Mar, 1976. Values are nunber killed
of 24 observations unless otherwise indicated. Only the
data for temperatures with asterisks were used in compu-

 

 

 

tations.
Tissue
Test Primary Secondary Tertiary
Pruning date temperature bud bud bud Cane
5 Dec, 1975 Control 9 12 2 O
-5* 14 7 3 4
-10* 11 5 6 3
-15* 202 162 132 9
-20 24 24 24 24
-25 24 24 24 24
8 Jan, 1976 Control 10 4 2 O
-5* 16 4 3 O
-10* 14 7 5 3
-15* 17 16 11 5
-20 24 24 23 24
-25 24 24 24 24
13 Feb, 1976 Control 9 3 3 O
-5* 10 4 O O
-10* 12 8 1 1
-15* 12 10 9 4
-20 24 24 24 24
-25 24 24 24 24
29 Feb, 1976 Control 10 3 2 O
-5* 112 62 22 1
-10* 9 9 3 1
-15* 14 10 9 5
-20 24 24 24 24
-25 24 24 24 24
30 Mar, 1976 Control 7 5 1 1
-5* 10 6 1 O
-10* 82 5 1 O
-15* 14 10 9 5
-20 24 24 24 24
-25 24 24 24 24

 

 

zNumber killed of 23 observations.

47

Table A12. Daily temperature maxima and minima (0C) for spring 1976
at the Michigan State University Horticultural Research

 

Farm.
Feb. Mar. Apr. May
1 -3 -5 11 -3 17 1 18 6
2 -2 -25 O -2 6 1 18 4
3 -9 -21 -1 -1 13 -3 12 1
4 -2 -8 6 4 17 -2 6 O
5 -4 -12 15 3 7 -3 16 11
6 -7 -12 11 -8 14 3 25 3
7 -7 -13 2 -2 16 1 6 O
8 0 -12 2 -9 12 -3 14 -1
9 1 -13 2 -4 7 -6 23 7
10 7 -10 7 -4 12 1 22 10
11 9 O 3 -6 17 -1 23 8
12 3 -4 4 -1 4 -6 14 1
13 9 2 14 -4 9 -3 16 2
14 3 -9 0 -6 17 6 23 14
15 3 -1 6 -4 24 16 23 15
16 16 -1 2 -3 27 15 19 16
17 3 O 2 -11 28 16 21 12
18 2 1 -1 -9 27 14 14 4
19 15 -1 13 9 27 14 16 2
20 4 -3 21 12 21 10 18 8
21 9 -1 19 1 14 8 24 9
22 1 -4 1 -9 21 8 21 4
23 -2 -12 4 -1 18 3 17 5
24 2 -9 12 7 16 5 16 3
25 14 7 21 4 13 5 17 6
26 17 6 16 5 6 -3 18 6
27 14 O 23 12 2 -2 20 6
28 17 1 4 -3 8 -1 23 11
29 11 1 12 2 14 O 22 15
30 13 4 15 2 18 14

(.0
H
N
(A)
.h
N
w
H

0'!

 

"I11111111114104