Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 1, 2012
Publication Date: March 22, 2012
Citation: Robins, J.G. 2012. Variation within accessions of switchgrass germplasm for dry matter yield and forage quality in a semiarid environment. Crop Sci. 52:2253-2261. doi: 10.2135/cropsci2012.01.0031. Interpretive Summary: Switchgrass germplasm was characterized for forage yield and forage quality under limited irrigation conditions at a field site in northern Utah from 2008 to 2010. To this point switchgrass has not been evaluated under limitied irrigation conditions in the arid western US. Substantial variation for forage yield and forage quality was identified among the germplasm sources. Based on the results, a set of eleven switchgrass germplasm sources was identified that exhibited high trait values at multiple harvests. This set of germplasm sources will be useful for switchgrass improvement for high agronomic value under drought conditions. However, the study also found that switchgrass production is not feasible in the western US without adequate irrigation.
Technical Abstract: Switchgrass (Panicum virgatum L.) is valued for conservation, forage, and biofuel in many areas of North America and worldwide. The extent of switchgrass productivity has not been characterized under semi-arid dryland conditions. Thus, a study was designed to characterize the variation within a set of 114 switchgrass germplasm accessions and six switchgrass cultivars for dry matter yield, crude protein, in vitro true digestibility, and neutral detergent fiber under limited and no supplemental irrigation conditions at a Millville, UT field site from 2008 to 2010. Variation among the accessions for each of these traits was greater than zero within individual harvests and across the four harvests. Repeatability across harvests was 0.70 for dry matter yield, 0.49 for crude protein, 0.36 for in vitro true digestibility, and 0.12 for neutral detergent fiber, and individual harvest repeatabilities were comparable for each of the traits. Accession variation was confounded by the accession by harvest variation that was also greater than zero for each trait. Nevertheless, a set of eleven switchgrass accessions, including the cultivar 'Cave-in-Rock' were identified that had consistently high phenotypic values for each of the traits at the several harvests. However, the results indicated production in semi-arid growing areas of the Intermountain U.S. for switchgrass productions are limited. For instance, the highest dry matter yield for any accessions was 3.6 Mg ha-1, which is substantially lower than switchgrass production in wetter areas of North America. Thus, switchgrass production in the Intermountain U.S. will not be feasible without supplemental irrigation. Nonetheless, the Intermountain US does have merit as a testing location for the development of more drought tolerant switchgrass and the identification of the eleven accessions with high phenotypic value provides material for use in switchgrass drought tolerance improvement program.