Genotypic variation in cold tolerance influences the yield of Miscanthus

When grown in Europe, Miscanthus genotypes often produce yields lower than their potential due to late emergence of shoots in the spring or to damage from late frosts when shoots emerge too early. Here, we investigate genotypic variation in the base temperature (T-b) for shoot emergence and in the lethal temperature for shoots (LT50) in four Miscanthus genotypes. In all genotypes, lowering temperature increased the time to shoot emergence, with T-b ranging from 8.6 degrees C in Sac-5 to 6 degrees C in Sin-H9. Frost treatments below -8 degrees C resulted in a marked reduction in growth in all four genotypes. Sin-H9 was the most frost tolerant with an LT50 of -9.3 degrees C. There was little variation found in leaf osmotic potential, but leaf moisture content was significantly lower in Sin-H9 than in the other genotypes. The lower thermal requirement for emergence and lower LT50 seen in Sin-H9 was incorporated into a model of Miscanthus production. The model showed an extended growing season that was predicted to increase yields by up to 25%.