Developing a screening protocol for chilling tolerance in miscanthus

Miscanthus is a high yielding, low input biomass crop. At present, only one variety, the natural hybrid M. x giganteus is commercially grown. New varieties will be developed to increase yield, lower the risk of diseases and pests and adapt the crop to environmental stresses, such as drought, salt and low temperatures. The EU FP7 project OPTIMSC aims to accelerate miscanthus breeding by trialing new elite germplasm in multiple locations across Europe and by identifying key traits related to abiotic stress tolerance. As low temperatures limit the growing season and restrict the cultivation area, a set of 100 genotypes will be screened for chilling tolerance. Tolerance to low temperature will result in earlier emergence and better spring growth. Considerable variation in tolerance to low temperatures must exist in M. sinensis and M. sacchariflorus, given the large geographical distribution of these species. Three different screening methodologies were tested on six miscanthus genotypes (5 M. sinensis and 1 M. sinensis x sacchariflorus hybrid) grown at 20°C and 12°C : i) leaf elongation, ii) plant height ii) photosynthesis and iii) chlorophyll fluorescence. The genotypes showed large variation in chilling tolerance. Leaf elongation rate decreased less in chilling tolerant genotypes. While photosynthesis decreases significantly between the two tested temperatures, the difference was not significant between the tested genotypes. Chlorophyll fluorescence showed good correlation to growth at 12°C and could be used to screen for chilling tolerant genotypes.