Genetic Variation in Biomass Yields of Lowland Switchgrass.

Switchgrass (Panicum virgatum L.) is a model plant species for lignocellulosic bioenergy feedstock production. It needs significant biomass yield improvement for its use as a viable bioenergy feedstock. In order to develop high yielding lowland cultivar for northern regions of the southern plain, we initiated selection on a locally adapted ‘Kanlow’ population of lowland switchgrass.  Using 4-yr old sward-plots established at the Holston unit of the University of Tennessee East Tennessee Research and Education Center, Knoxville, about 200 individual plants were selected based on phenotypic evaluations in the fall of 2011. Open pollinated seeds were harvested separately from each selected plant to constitute a halfsib family.  After seed threshing, cleaning, and germination; only 54 halfsib families produced enough seedlings for evaluation at two Tennessee locations, Knoxville and Crossville. The halfsib families were planted in the field in spring 2012 as a spaced-planted nursery. The trial was planted using a randomized completed block design with 3 replications. Each family in each replicate was planted in a single-row plot of 9 plants 30cm apart and 90cm bvetween rows. The biomass yield was recorded from established plots in fall 2013. Results demonstrated  significant genetic variation among halfsib families from original population source. The halfsib families ranked differently in biomass yields between locations. At Knoxville the mean biomass yield of the families was 17% higher than original population, while it was only 3% at the Crossville site. The presence of a few families producing higher biomass yields in both locations indicated the potential for development of improved varieties with stable performance across a broader range of environments.

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