Abstract
Species hybridization is key for the improvement of shrub willow (Salix spp.) bioenergy crops because hybrids often display heterosis for yield. The development of high-yielding genotypes requires numerous broad attempts at hybridization followed by field evaluation and selection for stable performance. Selection of improved shrub willow varieties for use as a bioenergy crop involves evaluation of full-sib progeny in family-based selection trials. Improving the accuracy of evaluation through the use of components of yield would greatly improve the efficiency of selection. Heterosis for biomass yield in intra- and interspecific F1 and F2 shrub willow crosses, made between Salix sections and ploidy, was examined by utilizing a suite of morphological, physiological, and chemical composition traits collected over the course of 12 weeks in the greenhouse and over 3 years in the field. Triploid families generated from diploid S. viminalis and tetraploid S. miyabeana displayed the greatest levels of heterosis for harvestable biomass and biomass-related growth traits in the greenhouse and in the field. While intraspecific S. purpurea diploids exhibited low levels of heterosis for these traits, interspecific diploids produced moderate levels of heterosis in greenhouse experiments. Differences between greenhouse and field trial results can largely be explained by pest damage, which negatively impacted interspecific diploids. Heterosis for the traits that form the basis for biomass yield, including stem growth, foliar, and physiological traits, was quantified, and family-level differences are discussed.
Highlights
Shrub willows (Salix spp., Salicaceae) are vigorous woody perennials that can be harvested to provide feedstocks for biofuel and bioenergy production [1]
The main objectives of this study were (1) to compare and contrast extensive phenotypic data collected among eight intraand interspecific shrub willow families, (2) to determine the extent to which these families display heterosis for biomass-related traits and biomass yield, and (3) determine if there is concordance of heterosis when plants are grown in the greenhouse compared with the field
Purpurea family 82 was generated from a cross between female 94006 and male 94001, both collected from naturalized S. purpurea populations in upstate NY
Summary
Shrub willows (Salix spp., Salicaceae) are vigorous woody perennials that can be harvested to provide feedstocks for biofuel and bioenergy production [1]. Found as pioneer species and in riparian habitats, the range of Salix extends from the arctic plains to the subtropics, with more than 350 species have been described [2,3]. Salix spp. are dioecious outcrossing perennials that are mostly entomophilous with possible low proportions of anemophily [4,5]. In sympatric populations of Salix, members within the same section will often hybridize, which can generate mixed populations of both pure species and species hybrids [7]. Vegetative clonal propagation can be a significant contributor to population structure in Salix, and has been shown to be fairly common in naturalized stands of North American S. purpurea [8]. Beyond the tremendous ecological amplitude, the heterogeneity and adaptive plasticity of
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
