Differential growth response to fertilization of ten elite shrub willow (Salix spp.) bioenergy cultivars
Shrub willow triploid hybrid cultivars obtained the greatest aboveground biomass compared to diploid and tetraploid cultivars, and greater biomass was highly correlated with leaf traits and rapid early stem elongation.
Shrub willow (Salix L. spp.) is a strong candidate for use as a dedicated bioenergy crop in moist, temperate climates due to high growth rates, excellent regenerative properties and relatively low nutrient demand. Large discrepancies exist in the literature as to the benefits of fertilization for improving biomass production. Controlled environment fertilization studies can remove some confounding edaphic and climatic factors present in field studies. Ten top-performing commercial or pre-commercial cultivars, mostly bred in the US, were assessed for response to five fertilization levels by measuring 20 biomass and growth traits. Triploid hybrid Salix viminalis × S. miyabeana cultivars had the greatest total aboveground biomass, as well as high stem biomass. There was a strong relationship between early stem growth and final aboveground biomass, but only under adequate fertilization. Different strategies for high biomass production among cultivars are discussed in the context of nitrogen investment in leaves. Comparing field trial results and this greenhouse experiment indicates that while the yield ranking is generally preserved, the greenhouse results diverged greatly for two cultivars.
KeywordsInterspecific hybrid Nitrogen use efficiency Salix miyabeana Salix purpurea Salix viminalis
We are grateful to Brian DeGasperis, Lindsey Mattick, McKenzie Schessl and Nick Durnin for their assistance with data collection and sample processing. We thank Armen Kemanian for careful review of an earlier version of this manuscript. Funding for this project was provided by the US Department of Agriculture National Institute of Food and Agriculture Federal Capacity Funds grant. Eric Fabio’s efforts were funded by the Agriculture and Food Research Initiative Competitive Grant No. 2012-68005-19703 from the USDA National Institute of Food and Agriculture.
ESF and LBS conceived and designed the experiment. ESF carried out the experiment, analyzed the data and prepared the manuscript. LBS reviewed and commented on the manuscript.
Compliance with ethical standards
Conflict of interest
LBS is an inventor on patented cultivars described here, and LBS and ESF are inventors on new technology disclosures for cultivars described here.
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