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Table 4 Influence of constant and changing temperatures on shoot structure and flowering of apple trees as assessed by out-door performance in the subsequent spring following overwintering in a cold store at 1 °C (2017 experiment)

From: Temperature control of shoot growth and floral initiation in apple (Malus × domestica Borkh.)

Cultivar

Temperature (°C)

Flowering nodes (%)

Vegetative nodes (%)

Non-breaking nodes (%)

Nodes per tree

Flower clusters per tree

Flowers per tree

Flowers per cluster

Days to anthesis from Apr. 27a

‘Summerred’

12 °C cont.

9.0 cb

82.2 a

8.8 b

158.0 b

14.3 d

41.0 c

2.9 bc

33.0 a

18 °C cont.

67.2 a

19.1 c

13.7 ab

165.0 b

111.0 b

455.0 a

4.1 a

27.0 bc

24 °C cont.

41.4 b

30.1 c

28.6 ab

395.7 a

164.0 a

491.3 a

3.0 bc

26.7 c

27 °C cont.

14.1 c

53.1 b

32.8 a

401.3 a

54.7 c

142.3 b

2.7 c

28.3 bc

Ambient

15.4 c

68.1 ab

16.5 ab

196.5 b

30.5 c

113.0 b

3.7 ab

29.5 b

 

1224 °C

29.6 A

50.4 A

20.0 A

232.0 A

69.5 B

211.5 B

3.0 A

27.0 A

1827 °C

30.7 A

45.5 AB

23.8 A

243.0 A

76.0 B

281.5 B

4.0 A

28.0 A

2412 °C

30.8 A

48.7 A

20.5 A

187.5 A

58.5 B

230.5 B

4.0 A

26.5 A

2718 °C

41.6 A

29.8 B

28.7 A

312.5 A

130.0 A

469.5 A

3.6 A

27.0 A

Mean

 

29.7

48.5

21.8

263.7

78.6

264.1

3.4

28.3

‘Discovery’

12 °C cont.

0.5 bc

65.6 ab

33.9 c

215.5 a

1.0 c

3.0 c

1.5 c

65.0 b

18 °C cont.

37.4 a

27.7 bc

34.9 bc

265.3 a

89.0 a

331.7 a

3.7 a

28.0 a

24 °C cont.

22.2 a

22.9 c

54.9 ab

326.0 a

74.0 a

200.5 a

2.8 b

26.5 a

27 °C cont.

6.5 ab

27.1 c

66.5 a

397.0 a

26.0 b

74.5 b

2.9 b

30.5 a

Ambient

3.6 b

68.3 a

28.1 c

241.5 a

8.5 c

20.0 c

2.3 bc

37.0 a

 

1224 °C

0.0 C

63.3 A

36.7 B

187.5 B

0.0 C

0.0 C

0.0 B

> 100 A

1827 °C

4.6 B

45.2 A

50.3 A

337.5 A

14.5 B

23.5 B

0.8 AB

66.0 B

2412 °C

11.3 AB

48.0 A

40.6 A

341.5 A

38.5 AB

122.5 AB

3.2 A

30.5 B

2718 °C

19.1 A

28.8 B

52.1 A

399.0 A

65.5 A

283.5 A

4.5 A

29.5 B

Mean

 

13.0

43.2

43.7

299.3

38.1

128.9

2.5

39.1

Probability level of significance by ANOVA

 Source of variation

  Cultivar (A)

 

ns

ns

ns

ns

ns

ns

0.05

0.001

  Temperature (B)

 

< 0.001

< 0.001

0.01

< 0.001

< 0.001

< 0.001

0.02

0.04

  A × B

 

0.003

ns

ns

ns

ns

ns

ns

ns

  1. The data are means of two trees from each treatment
  2. aFor non-flowering trees, number of days is set to 100
  3. bFor separation of means, Tukey’s multiple comparison test was performed separately for the two cultivars (lower case letters), and likewise for constant and changing temperatures (capital letters)