Late Emergence and Rapid Growth Maximize the Plant Development of Miscanthus Clones

To develop the perennial grass Miscanthus x giganteus as a highly productive crop for biomass production, new varieties need to be bred, and more knowledge about its growth behaviour has to be collected. Our aim was to identify an efficient function for assessing and comparing emergence date and canopy height growth (rate, duration, and final maximal height) of 21 clones of Miscanthus in Northern France. Flow cytometry made it possible to classify the clones into three clusters corresponding to 2x, 3x, and 4x ploidy levels. Three functions, 3- and 4-parameter logistic functions and Gompertz function, were tested to best describe the dynamics of crop emergence and of plant growth. The best functions were used to estimate emergence dynamics (Gompertz function), and growth dynamics (4-parameter logistic). All these traits showed a significant year, clone, and corresponding interaction effects (but not for harvest date). Species and ploidy level explained the clone and clone x year interaction effects. M. x giganteus and M. floridulus clones were among the latest to emerge, and the tallest. M. sinensis clones showed the lowest height and growth rates. Higher final canopy height was correlated to late emergence and high growth rate. These findings could help early selection of interesting clones within M. sinensis populations, in order to breed new inter-species hybrids of giganteus type.