Spring and autumn phenology of hybrid aspen (Populus tremula L. × P. tremuloides Michx.) genotypes of different geographic origin in hemiboreal Estonia§

New Zealand Journal of Forestry Science

Table 3 Mean onset of phenological stages and the interval between spring and autumn phenological stages in third and sixth growing season of hybrid aspen with P. tremula parent from Germany (DE), Finland (FI), Latvia (LV) and Sweden (SE)

Phenological stage	Third growing season				Sixth growing season
Phenological stage	DE	FI	LV	SE	DE	FI	LV	SE
	Onset of phenological stages, day of year
Bud-burst (S1)	119	125	122	122	119	129	123	119
All the leaves are unfolded (S2)	129	131	130	130	129	137	129	127
All the leaves have attained full-sized (S3)	143	144	141	142	144	147	143	144
Half of the leaves are yellow (A1)	274	267	272	272	261 ab	241 c	268 a	259 b
Defoliation of half of the leaves (A2)	290	282	285	289	277 a	251 b	279 a	273 a
Defoliation of all the leaves (A3)	308	302	302	308	301 ab	289 b	300 ab	307 a
	The interval between spring and autumn phenological stages, days
S1…A1	155	143	149	150	142 a	113 b	144 a	140 a
S1…A2	171	158	162	167	158 a	123 b	156 a	154 a
S1…A3	189	178	179	186	182 ab	161 b	177 ab	188 a
S2…A1	144	136	141	143	132 a	104 b	139 a	132 a
S2…A2	160	151	155	160	147 a	115 b	150 a	147 a
S2…A3	179	171	171	179	172 ab	153 b	171 ab	181 a
S3…A1	131	123	131	130	117 ab	95 c	125 a	115 b
S3…A2	147	138	144	147	132 a	105 b	136 a	129 a
S3…A3	166	158	161	166	157 ab	143 b	158 ab	163 a

Letters denote significant differences between geographical origins according to the Tukey LSD test. Differences between group means with no associated letters were not significant