Table 1.

Genotype, LT50 and FLN of near isogenic lines used in these studies

Line	Genotype	LT50	FLN
winter Norstar	vrn-A1, vrn-B1, vrn-D1	-23a	13a
spring Manitou	Vrn-A1, vrn-B1, vrn-D1	-8.3c	8c
winter Manitou	vrn-A1, vrn-B1, vrn-D1	-13.3b	10b
spring Norstar	Vrn-A1, vrn-B1, vrn-D1	-13b	11b

FLN (final leaf number) indicates the onset of the transition of the apical meristem from vegetative to reproductive stage; LT50 indicates the lowest temperature by which 50% of the treated samples survived after vernalization; a to c - within columns, means followed by the same letter are not different as determined by Duncan's new multiple range test (P < 0.05).