C₄bioenergy crops for cool climates, with special emphasis on perennial C₄grasses

Abstract

There is much interest in cultivating C4 perennial plants in northern climates where there is an abundance of land and a potential large market for biofuels. C4 feedstocks can exhibit superior yields to C3 alternatives during the long warm days of summer at high latitude, but their summer success depends on an ability to tolerate deep winter cold, spring frosts, and early growth-season chill. Here, we review cold tolerance limits in C4 perennial grasses. Dozens of C4 species are known from high latitudes to 63 °N and elevations up to 5200 m, demonstrating that C4 plants can adapt to cold climates. Of the three leading C4 grasses being considered for bioenergy production in cold climates--Miscanthus spp., switchgrass (Panicum virgatum), and prairie cordgrass (Spartina pectinata)--all are tolerant of cool temperatures (10-15 °C), but only cordgrass tolerates hard spring frosts. All three species overwinter as dormant rhizomes. In the productive Miscanthus×giganteus hybrids, exposure to temperatures below -3 °C to -7 °C will kill overwintering rhizomes, while for upland switchgrass and cordgrass, rhizomes survive exposure to temperatures above -20 °C to -24 °C. Cordgrass emerges earlier than switchgrass and M. giganteus genotypes, but lacks the Miscanthus growth potential once warmer days of late spring arrive. To enable C4-based bioenergy production in colder climates, breeding priorities should emphasize improved cold tolerance of M.×giganteus, and enhanced productivity of switchgrass and cordgrass. This should be feasible in the near future, because wild populations of each species exhibit a diverse range of cold tolerance and growth capabilities.

Field-grown miR156 transgenic switchgrass reproduction, yield, global gene expression analysis, and bioconfinement

“…Switchgrass ( Panicum virgatum L.) is a native North American perennial prairie grass mostly known for its use as a biofuel feedstock. The high biomass production, low input requirements, and its ability to be productive on marginal land are some features that make switchgrass an attractive cellulosic feedstock [ 1 , 2 ]. However, the high degree of lignification of secondary cell walls (around 20% of switchgrass dry cell wall biomass) inhibits biomass conversion to fermentable sugars and biofuel in switchgrass, which, in turn, is an economic barrier to biofuel production [ 1 – 5 ].…”

Impact of rhizome quality on Miscanthus establishment in claypan soil landscapes

“…Two major factors are air and soil temperatures during the winter and early spring following establishment (Hasting et al, 2009). Several previous studies have reported lethal M. × giganteus rhizome kill (>50%) during the first winter if soil temperatures drop below about −3.4 to −4.0 • C (Clifton-Brown and Lewandowski, 2000;Clifton-Brown et al, 2001;Kucharik et al, 2013;Friesen et al, 2015;Peixoto et al, 2015;Sage et al, 2015). However, some reports indicate that first-year M. × giganteus stands have consistently withstood harsher winter conditions; air temperatures as cold as −20 • C and soil temperatures as low as −6 • C (Heaton et al, 2010;Friesen et al, 2015).…”

Biomass for biofuel: Understanding the risks and opportunities for Ontario agriculture.

“…Perennial C 4 grass species have garnered the most attention as candidate dedicated biomass crops, particularly the C 4 species, switchgrass and Miscanthus. Although they are warmseason species, they are adapted to Ontario conditions (Sage et al 2015). They also have attributes required for sustainable biomass crop production: perennials with a 20+ year expected stand longevity, high yield potential (Heaton et al 2004), low input requirements, utilize existing commercial equipment for production ( Figs.…”

“…It has been estimated that 5% of all arable land (i.e., Class 1-5 lands) could provide over 2 million t yr −1 of dry matter of either switchgrass or Miscanthus biomass (Kludze et al 2013a). Due to higher yield potential, resulting from duration of leaf area as well as cold tolerance (Sage et al 2015), a Miscanthus biomass system compared with a switchgrass biomass system would require a lower percentage of available land area to produce an equivalent amount of biomass.…”