Submitted to: Crop Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/12/2003
Publication Date: 12/23/2003
Citation: CASLER, M.D., VOGEL, K.P., TALIAFERRO, C.M., WYNIA, R.L. LATITUDINAL ADAPTATION OF SWITCHGRASS POPULATIONS. CROP SCIENCE. 2003. v. 44. pp 293-303. Interpretive Summary: Switchgrass is a potentially important and widely adapted crop for use in biofuel production. We demonstrated that much of the inconsistency in biomass yield of switchgrasses across diverse locations can be explained by information on the origin of the populations and site characteristics. Upland and lowland types of switchgrass are distinctly adapted to northern and southern latitudes, respectively. Furthermore, there are northern- and southern adapted populations within both upland and lowland types. These differences in adaptation relate partly to the site of origin of each cultivar. Differential adaptation likely derives from photoperiodism, genetic variation for cold and heat tolerance, and thousands of years of natural selection. For optimal performance, cultivars should not be moved more that 5 degrees latitude north or south of their origin. There appears to be sufficient genetic variability within switchgrass to extend the adaption zones of both upland and lowland types by using plant breeding.
Technical Abstract: Switchgrass (Panicum virgatum L.) is a widely adapted warm-season perennial that has considerable potential as a biofuel crop. Broad species adaptation, natural selection, and photoperiodism have combined to create considerable ecotypic differentiation in switchgrass. The objective of this study was to determine the nature of population x location interaction for switchgrass, quantifying potential differences in latitudinal adaptation of switchgrass populations. Twenty populations were evaluated for biofuel and agronomic traits at five locations ranging from 36 to 46ºN latitude. Biomass yield, survival, and plant height had considerable population x location interaction, much of which (53 to 65%) could be attributed to the linear effect of latitude and to germplasm groups (Northern Upland, Southern Upland, Northern Lowland, and Southern Lowland). Differences among populations were consistent across locations for maturity, dry matter, and lodging. Laboratory traits (holocellulose, lignin, IVDMD, and N) were intermediate in population x location interaction. Increasingly later maturity and the more rapid stem elongation rate of more southern-origin ecotypes (mainly lowland cytotypes) resulted in high biomass yield potential, reduced dry matter concentration, and longer retention of photosynthetically active tissue at more southern locations, allowing switchgrass to extend its growth rate, taking advantage of a longer growing season. Conversely, increasing cold tolerance of more northern-origin ecotypes (mainly upland cytotypes) resulted in higher survival, stand longevity, and sustained biomass yields at more northern locations, allowing switchgrass to thrive at cold, northern latitudes. Although cytotype explained much of the variation among populations and the population x location interaction, ecotypic differentiation within cytotypes accounted for considerable variation in adaption of switchgrass populations.