桉树无性系顶梢伸长节律及其在良种选择中的潜在作用

Leading Shoot Elongation Rhythm and Its Potential Role in Selection of Eucalypt Clones

分析63个桉树无性系种植后第2年的顶梢伸长过程,并用一个Sigmoid-Logistic混合生长方程对每一无性系分别予以拟合。所有拟合结果均极为理想,拟合度(R2)高达0.97以上,拟合显著性水平P<0.0001,4个方程参数在拟合中作用突出,大多数情况下P<0.0001。顶梢伸长节律和林木生长均呈现出无性系间的变异;所有无性系均明显地呈现出早晚缓慢生长期和中间速生期;大部分无性系,特别是快速生长者,顶梢在气温较低的冬天仍然继续生长。秋冬季顶梢伸长是否停止或快慢可能说明桉树无性系林木对低温危害的敏感程度。根据顶梢伸长特征,可以将桉树无性系分成不同类型,选择适合不同需求的无性系。建议将种植区分成3类区域,并采用相应的无性系选育策略。

Leading shoot elongation was analyzed for 63 euealypt （Eucalyptus） clones over the second year after planted. The data were separately fitted for each clone against a Sigmoid-Logistic mixture of growth function. All fittings were excellent with extremely high goodness of fit （ R2 〉 0.99 ） and significance （ P 〈 0. 000 1 ）. All four function parameters played their fundamental role in the fitting with significance at level of P 〈 0. 000 l for most cases. Clona] variation obviously exhibited in the characters of shoot elongation and tree growth. All eucalypt clones clearly experienced early and late slow-growing periods and a fast growing period in between. A large part of clones, particularly fast-growing ones, continued to slowly elongate their shoots in the cold winter, while the remaining appeared otherwise. The shoot growth rate of eucalypt clones in the seasons of fall and winter may relate to their susceptibility to low temperature. Main shoot elongation parameters could be used to cluster eucalypt clones and to assist selection of clones for different objectives. It was suggested that the potential planting region would be demarcated into 3 zones, and the corresponding selection and breeding strategies. ：