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种子园建园技术中,非常重要的一个环节就是选择优树[1]。对于水曲柳而言,由于其材质比较坚硬,用生长锥钻到髓心测年龄很困难。根据树干解析材料,经过分析、研究、实践、比较后发现,水曲柳选优采用树干北面胸径外径7 cm年轮数法既准确又简捷。即先在整个选优范围内随机选取水曲柳50株以上,钻取树干北面胸径外径7 cm芯,查取年轮数,计算平均数与标准差,用平均数减去1倍标准差(40a)确定为选优标准。在选择优树时,当其它指标合乎要求后,年轮数小于40入选。
Seed garden construction technology, a very important part is to choose the best tree [1]. For Ash, due to its relatively hard material, the use of growth cone drill to the center of the pith to measure the age is difficult. According to the analysis of the trunk material, after analysis, research, practice and comparison, we found that the optimal choice of ash is 7cm annual diameter at the north diameter of the trunk is accurate and simple. That is to say, the first random selection of more than 50 Ash in the selected range, drilled diameter 7 cm core bore diameter north of the trunk, access to the number of annual rings, calculate the mean and standard deviation, with the average minus 1 standard deviation (40a) as the selection criteria. When choosing the superior tree, when other indicators are satisfactory, the annual number of rounds is less than 40 selected.