The frost tolerance of Miscanthus at the juvenile stage: Differences between clones are influenced by leaf-stage and acclimation

Abstract

Miscanthus, a perennial, C 4 grass, has numerous advantages for biomass production, notably its high yield per hectare and low input requirements. However, establishment of this crop may be affected in Europe by frost damage when stem emergence occurs early in the year. The principal aim of this study was to quantify the impact of frost on young miscanthus shoots at different leaf-stages, and to characterise inter-species variations in frost tolerance. Four clones belonging to two species were tested at three leaf stages in a climate-controlled chamber simulating acclimation conditions and frost treatments. Frost tolerance was scored using a 0–6 visual assessment scale and analysed with nonparametric tests. We were thus able to show that more developed plants (6 or 7-leaf stage) were less frost tolerant than those at the 3 or 5-leaf stage. Plants at the 6 or 7-leaf stage also displayed differences in tolerance between clones. The leaf-stage of the plant is linked to apex height, and this appeared to play a role in frost tolerance. M. sinensis displayed variable frost tolerance (tolerance score of between 3.6 and 4.9), although the three clones observed were always more frost tolerant than M. x giganteus (with a score of 3). Moreover, the differences in frost tolerance were negatively correlated ( r = −0.94) with the mean leaf surface area of clones at the time of frost exposure. Finally, we observed that acclimation at 12 °C under strong light intensity (600 μmol m −2 s −1) enabled an increase in the tolerance of young shoots in all the clones tested.