Growth of riparian cottonwoods: heterosis in some intersectional Populus hybrids and clonal expansion of females

Autor: Stewart B. Rood, David R. McCaffrey, Lori A. Goater, David W. Pearce, Chris Hopkinson, Joshua Montgomery
Rok vydání: 2017
Předmět:
Zdroj: Trees. 31:1069-1081
ISSN: 1432-2285
0931-1890
Popis: A field study revealed that some native intersectional hybrids of riparian poplars (Populus species) demonstrated faster growth than the parental species, and this was increased for female genets due to their greater clonal expansion. To investigate the diversity and adaptation of cottonwoods, riparian poplars, we observed all trees on an island in southern Alberta, Canada over a span of two decades. This woodland included the section Tacamahaca balsam poplar, Populus balsamifera (B), and narrowleaf cottonwood, P. angustifolia (A); and the section Aigeiros prairie cottonwood, P. deltoides (D), along with their natural interspecific hybrids. There were differences in sizes and growth across the taxa, and basal area increments revealed that some of the intersectional hybrids, A×D (P.×acuminata) and BxD (P.×jackii), displayed the greatest growth, followed by the sequence: B ~ D > A×B (intrasectional hybrids) >A. This revealed variation across the taxa and suggests that sufficient genetic distance is required for heterosis, although only some intersectional hybrids displayed hybrid vigor. Within some taxa, female trunks were generally larger and females produced more clonal ramets, providing ‘clonal amplification’ that resulted in larger overall genet sizes, especially for the intersectional hybrids. Thus, these females outperformed males in this environmentally favorable environment caused by an artificially stabilized water table. In addition, members of a large clone displayed synchronous mortality, indicating that physiological interconnections persist over decades. These results reveal interacting genetic and environmental influences on the growth, clonality, and mortality of these Populus species and their native hybrids in a natural riparian woodland. The differing characteristics among taxa and the sexes would influence their adaptation and their suitability for reclamation or other plantings and for contributions to hybrid poplar breeding programs.
Databáze: OpenAIRE
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