Regional Collaborative Research On Cold Tolerance of Exotic Biofuel Grasses.

Cold tolerance is a selectable trait for many exotic grasses, even those of tropical or subtropical origin.  We are conducting cold tolerance assessments on an array of perennial biofuel grasses at Booneville, AR.  In study one (published), we reported that two sugarcane clones (US84-1028 and US84-1058) derived from sugarcane X Miscanthus sp. had stubble cold tolerance (overwintered), and that yield of US84-1028 is generally comparable to ‘Alamo' Panicum virgatum (native) and proprietary M. x giganteus (Q42641) in 1^st stubble.  Across entries, leaves have about twice the N of stems (≤15.2 and 7.8 g kg^-1, respectively), have large cellulose (≤482 g kg^-1) and lignin (167 g kg^-1) concentrations, and comprise about one-third the total aboveground biomass.  In study two (preliminary), Arundo donax yielded 40 Mg ha^-1 with supplemental irrigation and 30 Mg ha^-1 without irrigation, while M. x giganteus and US84-1028 yielded 8 and 3 Mg ha^-1, respectively, in 1^st stubble.  However, US84-1028 lacked persistence in 2^nd stubble, unlike Arundo donax and M. x giganteus.  In study three (preliminary), three Pennisetum purpureum clones generally lacked stubble cold tolerance, while three Erianthus arundinaceus and six sugarcane clones varied in stubble cold tolerance.  In study four (preliminary), sugarcane progeny with E. arundinaceus parentage had substantial stubble cold tolerance with nearly 50% survival in 1^st stubble.  In study five (preliminary), Phyllostachys bissetii and P. rubromarginata produced more primary shoots plot^-1 than P. purpurata and P. propinqua 3 yr after establishment from bare rhizomes on a minimally-managed upland site.  Phyllostachys sp. may emulate a short-rotation woody crop in harvest scheduling.  In study six, we will examine cold tolerance of 16 Bambusa sp., Phyllostachys sp., and Semiarundinarea sp. in Arkansas and Missouri.  The research should increase the number of candidate clones for breeding and biomass production in the west-central US.