Submitted to: Crop Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/28/2003
Publication Date: 10/30/2003
Citation: Casler, M.D., Boe, A.R. 2003. Cultivar x environment interaction in switchgrass. Crop Science. 43(6):2226-2233. Interpretive Summary: Switchgrass is a potentially important and widely adapted crop for use in biofuel production. We evaluated six switchgrass cultivars of diverse origins for biofuel traits. A late summer or early autumn harvest date was optimal for these northern locations (South Dakota and Wisconsin), largely due to increased stands and biomass production over the long term. Broadly adapted, broadly unadapted, and specifically adapted cultivars of switchgrass were identified. It should be possible, through selection and breeding, to develop switchgrass germplasm with increased availability of fermentable sugars and decreased unfermentable and/or incombustible residues. The study provides valuable information on optimal harvest dates and adapted cultivars to switchgrass producers and other scientists.
Technical Abstract: Switchgrass (Panicum virgatum L.) is a widely adapted warm-season perennial that has considerable potential as a biofuel crop. The objectives of this study were to estimate the effect of harvest date on switchgrass cultivars at two locations in the north central USA and to determine the relative importance of cultivar x environment interactions for agronomic and biofuel traits of switchgrass. Six cultivars were grown in southern Wisconsin and eastern South Dakota for 4 years, harvested each year at three harvest dates (August, September, and October). Cultivars differed widely in biomass yield, but had statistical interactions with all environmental factors. Biomass yield did not respond consistently to harvest date, varying with cultivar, location, and year. Despite these interactions, cultivar rankings for biomass yield tended to be consistent across harvest dates and years, but not locations. There appeared to be some preferential adaptation to either Wisconsin or South Dakota, related to longitude of the original germplasm collection site, also reflected by ground cover data. Reduced stands and biomass yields for the August harvest data in later years suggested that late summer or early autumn harvest may be beneficial in the long term. Mean dry matter, forage fiber, and lignin concentrations varied among cultivars, and showed no interactions with locations and years. These three traits all increased with later harvest consistently across locations and years. However, the rate of increase varied among cultivars. It should be possible, through selection and breeding, to develop switchgrass germplasm with increased fiber and decreased lignin and ash, increasing the availability of fermentable sugars and decreasing the unfermentable and/or incombustible residues.