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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)

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

Phenological stage Third growing season Sixth growing season
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
  1. Letters denote significant differences between geographical origins according to the Tukey LSD test. Differences between group means with no associated letters were not significant