Table II. Effects of altitude on flowering time of vernalized plants.

A linear mixed-effects model was used with altitude (linear and quadratic terms) and vernalization treatment including their interactions as fixed factors and genotypes as random factors. Heteroscedasticity between treatments was accounted for by using the weights argument in the lme function.

Condition	Estimate	se	tdfa	P
Altitude, linear	30.769	10.235	3.006292	0.003
Altitude, quadratic	−33.856	10.202	−3.319292	0.001
6 Weeks of vernalization	−6.538	0.304	−21.512292	<0.001
12 Weeks of vernalization	−15.789	0.290	−54.442292	<0.001
Altitude (linear) × 6 weeks	−10.800	5.321	−2.030292	0.043
Altitude (quadratic) × 6 weeks	7.340	5.297	1.386292	0.167
Altitude (linear) × 12 weeks	−13.379	5.071	−2.638292	0.009
Altitude (quadratic) × 12 weeks	5.463	5.056	1.081292	0.281

^at value and degrees of freedom.