Table 3. Partial–correlation coefficients and variable selection decisions on growing condition variables based on the field trial data collected from 1983 to 2008

Growing condition variable	Partial-correlation coefficient	Decision
Accumulated temperature within the temperature range1)
0°C to 25°C	0.696**	Selected
0°C to 30°C	0.685	Eliminated
Above 0°C	0.685	Eliminated
5°C to 25°C	0.555**	Selected
5°C to 30°C	0.542	Eliminated
Above 5°C	0.536	Eliminated
10°C to 25°C	−0.484	Eliminated
10°C to 30°C	−0.530**	Selected
Above 10°C	−0.527	Eliminated
Sunshine duration (hr)
0°C to 25°C	0.148*	Eliminated
5°C to 25°C	0.237**	Selected
Duration of temperature (day)
0°C to 25°C	0.576**	Selected
5°C to 25°C	0.481**	Eliminated
Daily mean temperature > 25°C
Days > 25°C	0.483**	Selected
Accumulated temperature > 25°C	0.488**	Selected
January temperature (°C)
Daily mean	0.410**	Eliminated
Daily low	0.466**	Selected
Rain day (day)
Over 0 mm	0.154*	Selected
Over 5 mm	0.092	Eliminated
Precipitation amount (mm)
Accumulated rainfall over 0 mm	−0.021	Selected
Accumulated rainfall over 5 mm	−0.015	Eliminated
Soil property2)
Clay content (%)	0.322**	Selected
Drainage (nominal)	0.089	Selected

The base temperature was 5°C.
Jitter-transformation was applied to transform the soil characteristics into continuous variables.
Significant at p < 0.05
p < 0.01, respectively.