The annual shoot elongation could be described by a non-linear growth model to characterize differences in its dynamics among spruce genotypes, the effect of each shoot elongation phase on the total shoot length, and the genetic differences for a particular growth phase. The terminal shoot length was measured in two open-pollinated progeny trials of Norway spruce on average once per week during the ninth growing season. For the analysis, 10% of families with the longest annual increment (shoot) and 10% with the shortest were selected for each trial. The Gompertz model was fitted to individual tree data, and the mean values of its coefficients for each group of families were obtained. Family significantly (p < 0.001) affected total shoot length and all growth rhythm parameters, with similar trends reported in both studied sites. Heritability of Gompertz model coefficients in most cases exceeded that of the tree height. The superior10% of families started shoot elongation slightly but non-significantly earlier (all p > 0.05) than the other groups of families and had more intense shoot elongation (mm per day) during the entire growing season. A strong negative relation was found between the slope coefficient of the cumulative shoot elongation lines and the total height increment. The group of families with the longest increment had flatter relative shoot elongation lines, indicating relatively more evenly distributed growth within the growing season. In contrast, families with the shortest increment tended to accumulate a higher proportion of height increment during the active growth phase and reduced relative growth intensity more rapidly. The 10% of families with the largest annual increment showed superior characteristics in all shoot elongation phases, resulting in 30–40% longer shoots compared to the 10% of families with the smallest annual increment. The significant differences in Gompertz model coefficients indicate that genotypes with favorable growth patterns might be selected.

中文翻译：

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挪威年轻云杉年梢伸长的遗传差异

可以用非线性生长模型描述年生芽伸长，以表征其在云杉基因型之间的动力学差异，每个芽伸长期对总芽长的影响以及特定生长期的遗传差异。在第九个生长季节中，挪威云杉的两次开放授粉后代试验平均测量一次末梢的长度。为了进行分析，为每个试验选择了10％的年度增量（拍摄）最长的家庭和10％的年度增量最短的家庭。将Gompertz模型拟合到单个树数据，并获得每组家庭的系数平均值。家庭显著（p<0.001）影响了总苗长和所有生长节律参数，在两个研究地点报告的趋势相似。在大多数情况下，Gompertz模型系数的遗传力超过了树的高度。优越的10％的家庭开始出现芽伸长的时间略短，但不明显的早一些（所有p> 0.05），并且在整个生长季节中枝条伸长率（每天mm）更高。发现累积枝条伸长线的斜率系数与总高度增量之间存在很强的负相关关系。增量最长的家庭组的相对芽伸长线较平坦，表明在生长季节内相对较均匀地分布了生长。相比之下，增长最短的家庭在活跃的生长阶段倾向于积累较高比例的身高增长，而相对增长强度下降得更快。年增长率最大的10％的家庭在所有枝条伸长阶段均表现出优异的特性，与年增长率最小的10％的家庭相比，芽长30–40％。