Two Methods of Selecting Parents to Produce High Yielding, Lowland Switchgrass Synthetic Cultivars.

Switchgrass (Panicum virgatum L.) is now the main herbaceous species for use as cellulosic biomass. Using one thousand, randomly selected genotypes from ‘Alamo’ placed initially as single rep, spaced plants in “honeycomb design”, two experimental cultivars were developed using the following methods: Method #1 - selection of the best genotypes after the second production year (traditional approach) in the initial honeycomb, followed by production of half-sib families from the initially selected genotypes, followed by a two-year, two-location sward planted, half-sib family performance trial (again, traditional), then selection of the best genotypes for use as parents to produce a new synthetic cultivar based on the yield of their half-sib  families; and Method #2 – selection of the best genotypes after one year in the initial honeycomb, followed by production of half-sib families from the selected genotypes, followed by testing of the half –sib families in a replicated honeycomb family design for one year at one location, then selection of the best genotypes for use as parents to produce a new synthetic cultivar based on their half-sib family honeycomb performance.  The objective of this current research was therefore to assess the suitability of these two methods to produce good cultivars by comparing the yield of the experimental cultivars produced from each method.  In a three year performance trial, both experimental cultivars were not significantly different in yield from each other, but both showed significantly higher yields over parent population Alamo in all years.  The cultivar from Method #2 was produced two years sooner, and with fewer resources, than the cultivar from Method #1, therefore Method #2 would be a good procedure if speed to release is a primary objective.