Latitudinal and Longitudinal Adaptation of Switchgrass Populations

Abstract

Switchgrass (Panicum virgatum L.) is a warm‐season native grass, used for livestock feed, bioenergy, soil and wildlife conservation, and prairie restoration in a large portion of the USA. The objective of this research was to quantify the relative importance of latitude and longitude for adaptation and agronomic performance of a diverse group of switchgrass populations. Six populations, chosen to represent remnant prairie populations on two north–south transects, were evaluated for agronomic traits at 12 locations ranging from 36 to 47°N latitude and 88 to 101°W longitude. Although the population × location interactions accounted for only 10 to 31% of the variance among population means, many significant changes in ranking and adaptive responses were observed. Ground cover was greater for northern‐origin populations evaluated in hardiness zones 3 and 4 and for southern‐origin populations evaluated in hardiness zones 5 and 6. There were no adaptive responses related to longitude (ecoregion). Switchgrass populations for use in biomass production, conservation, or restoration should not be moved more than one hardiness zone north or south from their origin, but some can be moved east or west of their original ecoregion, if results from field tests support broad longitudinal adaptation.

Post-glacial evolution of Panicum virgatum: centers of diversity and gene pools revealed by SSR markers and cpDNA sequences

“…Flowering time and photoperiod response are probably the most important traits regulating adaptive variation in switchgrass. For most cultivars, adaptation and productivity decrease significantly when the cultivar is grown in more than one hardiness zone north or south of its origin (Casler et al 2004(Casler et al , 2007b. More recent applications of DNA markers and sequencing methodologies have suggested that both cpDNA sequence data and nuclear DNA markers are highly correlated with the upland and lowland phenotypic classes.…”

“…Mutations that resulted in earlier flowering and tolerance to longer daylength, allowed certain genotypes to complete cold-hardening cycles and produce ripe seed at more northern latitudes. Divergence in flowering time and photoperiod sensitivity is the basis for much of the phenotypic variability observed within the species today (Casler et al 2007b). The vast majority of phenotypic variability in switchgrass occurs along latitudinal gradients, with earlier flowering, fewer phytomers, greater tiller density, reduced tiller size, and more compact panicle structure associated with more northern origins (Casler et al 2004(Casler et al , 2007b.…”

“…Divergence in flowering time and photoperiod sensitivity is the basis for much of the phenotypic variability observed within the species today (Casler et al 2007b). The vast majority of phenotypic variability in switchgrass occurs along latitudinal gradients, with earlier flowering, fewer phytomers, greater tiller density, reduced tiller size, and more compact panicle structure associated with more northern origins (Casler et al 2004(Casler et al , 2007b. Much of this variability is associated with the two dominant ecotypes of switchgrass, but there is considerable within-ecotype phenotypic variability that appears to be adaptive in nature, likely resulting from selection and not associated with ploidy level per se.…”

Stress-Tolerant Feedstocks for Sustainable Bioenergy Production on Marginal Land

“…Electrolyte leakage was lowest in "Dakota" compared with all other grasses tested, and CIR was close to the highest [214]. Lowland cytotypes are particularly susceptible to cold winter conditions, as they are adapted to southern latitudes [222,223]. Panicum virgatum shows unusual tolerance to cold night temps for a C 4 grass [224].…”

“…Panicum virgatum C4 Moderate Lowland cytotypes of Panicum virgatum, adapted to southern climates, may be more heat tolerant than upland types [223]. Even though plant height and total biomass decreased under heat stress [249], a climate modeling paper shows that Panicum virgatum yields could increase under warmer climate scenarios (3 to 8°C), due to extended growing season and limited cold stress [211].…”