Divergence among mother trees of Handroanthus serratifolius (Vahl) S. O. Grose regarding seed quality traits

ABSTRACT Environmental influences and genetic variability can promote, within the same species, variations between plants with intrinsic traits to the seeds. This work aimed at investigating the divergence among Handroanthus serratifolius mother trees from traits related to the physiological quality of seeds. Seeds collected from 13 mother trees were submitted to tests germination, electrical conductivity (EC), cold, controlled deterioration, and accelerated aging. Five replications of 50 and 25 seeds each were used for the cold test and other tests, respectively. The average data per mother tree were submitted to cluster analysis by the methods of Ward, k-means, and Principal Component Analysis (PCA). The mother trees were grouped into 4 clusters by the Ward’s and K-means methods, and confirmed by the PCA, but with varying cluster compositions. Cluster 2 grouped the mother trees with lower seed quality as demonstrated by the lowest values for most of the evaluated traits, but the highest EC and the second-highest value for the germination uncertainty index. On the other hand, cluster 4 grouped the mother trees with better seed quality. Of the 22 evaluated traits, eight are probably suitable for discarding due to their little contribution to the original variability. The results of the different clustering methods indicate significant differences between the mother trees regarding the physiological quality of seeds, showing that these parameters may be used to guide breeding programs aiming to produce high-quality seeds and seedlings of H. serratifolius.

摘要：环境影响与遗传变异可引发同一物种内不同植株的种子固有性状产生差异。本研究旨在探究齿叶蚁木（Handroanthus serratifolius）母树间与种子生理品质相关的性状差异。研究人员从13株母树上采集种子，分别开展发芽试验、电导率（electrical conductivity, EC）测定、低温试验、控制劣变试验与人工老化试验。其中低温试验每组设置50粒种子，其余试验每组设置25粒种子，均设5次重复。每株母树的平均数据分别采用沃德法（Ward）、K均值法（k-means）与主成分分析（Principal Component Analysis, PCA）进行聚类分析。沃德法与K均值法将母树划分为4个类群，该结果经主成分分析验证，但各类群的组成存在差异。类群2包含的母树种子品质较差：多数被测性状数值最低，电导率最高，且发芽不确定性指数位列第二。与之相对，类群4包含的母树种子品质更优。在22个被测性状中，有8个性状对原始变异贡献极小，或可予以剔除。不同聚类方法的结果表明，母树间的种子生理品质存在显著差异，说明这些参数可用于指导旨在培育优质齿叶蚁木（H. serratifolius）种子与幼苗的育种项目。