马尾松实生种子园五年生的植株生长与分枝

本文研究了马尾松实生种子园建立第五年时植株的生长与分枝状况,研究的性状包括树高、胸径、枝条总数、年高生长、 年枝条生长量、年分枝数、不同分枝处树干直径等。对总的生长与分枝性状(含树高、胸径、枝条总数)分析表明:家系间只在胸径方面存在显著差异。对分年度的生长与分枝性状的研究表明:家系间在年高生长、年枝条生长量、年枝条直径方面无显著差异;年分枝数在刚建立的前两年家系间没有显著差异,后两年则差异显著;不同分枝处树干直径在连续的四年内,家系间均存在显著差异。不同年度的生长与分枝的趋势分析结果发现,大部分家系的年高生长与年枝条生长呈递增型,而大部分家系每年的分枝数却为波动型。这些研究结果表明,该马尾松实生种子园到建立的第五年时,家系间的差异大部分都不显著。究其原因,一方面可能是马尾松初期生长节律;另一方面可能是因为建园家系复杂的父本构成。因此,这个时期进行家系选择不太有效,建议在利用优树自由授粉子代建立实生种子园时,对他们先期进行苗期选择,而不是采用所有的子代。图1表4参20。

Branching and growth of plantings in fifth year of a seedling seed orchard of Masson pine (<Emphasis Type="Italic">Pinus massoniana</Emphasis> Lamb.)

The features of branching and growth studied included height, diameter at breast height (DBH), total number of branches, annual height growth, annual branch elongation in the year of elongating, annual branch number for four consecutive years, diameter of branches of different ages, and diameter of stem where branch-whorl originates. For features of total growth and overall branching, no significant differences were found between families, except for DBH. For annual features, no significant differences were found in annual stem height growth, annual branch elongation in the year of elongation and diameter of branches. In the last four years, differences in number of branches were not significant in the first two years but were significant in the last two year; differences in stem diameter where branch-whorls grow were significant for the four consecutive years. Trend of annual growth and branching features of families can be divided into three types as increasing type, stable type and fluctuating type. Most of families have an increasing type with respect of annual height growth and annual branch elongation, while most families belong to a fluctuating type with annual branch number. The results indicated that in the fifth year after planted in seedling seed orchard, differences between families were mostly insignificant. This result may have two main explanations: one is the growth rhyme in early ages of Masson pine, the other one is the complex paternal components to form the open-pollinated families. Family selection seemed to be not useful based on the result. It is suggested to select some of families in the nursery instead of to use all the families when establishing seedling seed orchards with open-pollinated families from plus-trees.