Cold-tolerance of Miscanthus seedlings and effects of spring and autumn frosts on mature clonally replicated cultivars

Miscanthus is a genus of perennial, warm season grasses that is a leading candidate for bio-mass production in temperate environments. Relative to other C₄ grasses, some Miscanthus genotypes have exceptionally efficient photosynthesis at low temperatures. Typically planted at about the same time as maize (Zea mays L), it is unknown if earlier planting of Miscanthus would be possible or even preferable. Moreover, little is known about the response of Miscanthus to frosts. The aim of this study was to determine low temperature thresholds for damage and death of Miscanthus seedlings in a controlled environment chamber, quantify the effect of early planting dates for Miscanthus seedlings in the field on survival, growth, and yield, and assess genotypic differences for spring and autumn frost tolerance for field plantings of established clonal materials. We observed that Miscanthus seedlings and mature plants had exceptional cold tolerance for a C₄ grass. In a controlled environment chamber, 29 to 65% of seedlings in four Miscanthus populations subjected to a 12 h cold treatment at -10°C survived, whereas none of the maize seedlings survived a 1°C treatment. In the field, all Miscanthus seedling populations tested had ≥66% survival in 2011 and 2012, despite light freezes associated with planting in mid-March at Urbana, IL. The standard for biomass production, M. xgiganteus J. M. Greef & Deuter ex Hodk. & Renvoize, had low frost tolerance relative to other genotypes, indicating potential for genetic improvement.