Physiological Response of Woody and Herbaceous Biomass Feedstock Crops to Flooding.

Production of biofuel from corn or other food crops is unsustainable since it creates artificial shortages in food supply, increases in food price, and subsequent socio-economic and environmental consequences. Second generation biofuels, however, have shown promise with improvement in technologies for converting cellulosic feedstock into liquid transportation fuels. Promising biomass species include short rotation trees such as cottonwood (Populus spp.) and willow (Salix spp.), perennial grasses such as miscanthus (Miscanthus spp.) and switchgrass (Panicum spp.) and annuals like high biomass sorghum (Sorghum spp.). The objective of this study is to evaluate the performance and suitability of four promising biomass species for survival, establishment, and flood tolerance in a midwestern floodplain. Fifteen varieties/cultivars each for poplar, willow, switchgrass, and sorghum (three replicates) were planted in the flood lab located at the Horticulture and Agroforestry Research Center (HARC) of the University of Missouri Columbia. Imposed flood treatments were 0, 1, 3 and 6 weeks. Establishment of willow, poplar, switchgrass, and sorghum was recorded. Willow average height after 12 weeks after planting (WAP) was 32.88 cm while for cottonwood the average height was 39.58 cm. Average sorghum height was 53.5 cm at 8 WAP, while switchgrass achieved an average height of 48 cm at 8 weeks after transplanting. Severe drought in 2012 resulted in the loss of willow trials and therefore flood tolerance was evaluated for the other three species. Flood treatments were initiated approximately 75 days after planting. At least 15 cm of standing water was maintained in the channels during the period of flooding. Cottonwood and switchgrass showed high tolerance to prolonged flooding. Some biomass sorghum cultivars were susceptible to lodging. The results of this experiment suggests that biomass feedstocks species tolerant to prolonged flooding may be established in river floodplains, which are not suitable for production agriculture.