Table 2 Linear Mixed Model analysis of the relationship between mean trial temperature (25th Nov–21st Dec; DecTm2), trial site, variety and WOSR yield.

From: Yield instability of winter oilseed rape modulated by early winter temperature

Predictor variable

d.f.

F statistic

Estimate (kg ha−1 °C−1) ± SE

Significance

Locations & varieties used in at least 5 years (1685 yield data)

Location

20, 140

5.09

 

P < 0.001

YearL

1, 153

0.72

−13 ± 15

P = 0.4

OctTm (BBCH14–19)

1, 141

2.55

57 ± 36

P = 0.1

DecTm (BBCH (20–29)

1, 156

26.46

−127 ± 25

P < 0.001

YearL and OctTm removed from model

Location

20, 142

5.04

 

P < 0.001

DecTm

1, 158

24.12

−116 ± 24

P < 0.001

Locations used in at least 2 years (6378 yield data)

Location

36, 170

4.40

 

P < 0.001

YearL

1, 177

0.00

1 ± 14

P = 1.0

OctTm (BBCH14–19)

1, 171

1.48

39 ± 32

P = 0.2

DecTm (BBCH (20–29)

1, 179

28.78

−122 ± 23

P < 0.001

YearL and OctTm removed from model

Location

36, 172

4.41

 

P < 0.001

DecTm (BBCH (20–29)

1, 182

27.80

−113 ± 21

P < 0.001

  1. The contributions of fixed effects are shown. Location: trial sites or groups of sites (Table S1). YearL: the linear effect of year fitted as a numerical variable. Random effects were Variety + Variety.DecTm + Location.Year in all models; in the latter case, Year is fitted as a factor to explain year-specific variation at trial locations. n/a: not applicable.
Back to article page