林木卵形叶片形态指标提取软件及其在杨树中的应用

A Software Package for Extracting Shape Indices of Oval Tree Leaves and Its Primary Application in Populus

为准确观测林木叶片形态的表型数据,采用R语言以及一些图像处理软件包编写1个新的软件包名为LeafShape,将叶片的扫描图像文件作为输入对象,提取叶片长、宽和面积以及其边缘点的数值。利用该软件包获取美洲黑杨和小叶杨杂交F1代无性系随机区组试验林中181个家系共2 496个单株叶片数据,根据描述性统计量、相关分析和混合线性模型方法分析叶片的表型和遗传变异,同时根据叶片高密度边缘点的遗传效应值对叶片的形态进行聚类分析。结果表明:叶片的长、宽变异系数为20%~25%,而叶片的面积变异系数却高达42%;叶片的长、宽和面积两两之间高度相关,大部分相关系数大于0.90。叶片的长、宽和面积的表型变异主要归因于遗传变异,其无性系的重复力均在60%以上,其中2/3叶宽的重复力最大为72%。根据叶片360个边缘点极径的遗传效应值,181个家系的叶片形态被分成9个类,而这9个类又明显地分为2类:一类叶片形态偏向于母本美洲黑杨,而另一类则偏向于父本小叶杨。

To extract the phenotypic data of leaf shape accurately, we used R language to write a package LeafShape for extracting leaf length, width, and area as well as edge digital characters by using leaf scanned image as input file. With this package, 2 496 leaf phenotypic data of 181 families were extracted in a clonal randomized block test derived from an F1 hybrid progeny of Populus deltoides and P. simonii. Descriptive statistics, correlation analysis, and mixed linear model were applied for analyzing the phenotypic and genetic variations. In addition, clustering analysis was performed for leaf shapes according to the genetic effects of the polar radii at the leaf edge points. The findings indicated that the coefficients of variation(CV) in leaf length and width were in the range from 20% to 25% and the leaf area had the largest CV value of 42%. There were extremely significant correlations among leaf length, width, and area, with most correlation coefficients higher than 0.90. Furthermore, the phenotypic variations of the leaf length, width, and area were attributed to the genetic variation, each with a repeatability over 60% and that of 2/3 leaf area up to the highest value of 72%. Additionally, 181 clonal families were clustered into 9 groups according to the genetic effects of the polar radii at the 360 edge points. It is obvious that the 9 clusters of leaf shapes can be divided into 2 major groups, one close to the female parent P. deltoides and the other to the male parent P. simonii.