Phenomics analysis of drought responses in Miscanthus collected from different geographical locations

Miscanthus is a genus of C4 perennial grasses capable of high biomass potential even in temperate regions making it an ideal industrial crop for the renewable supply of energy and chemicals. Yield is strongly linked to water availability and many environments have limited water supply where otherwise irradiation and temperature are favourable. A total of 47 Miscanthus genotypes, diverse regarding collection site and genotype, were screened in a high-throughput phenomics facility under drought to generate high-quality time-course data for biomass accumulation and water use. Plants were subjected to three treatments: a watered control, mild drought (20% of field capacity), and a severe drought (water completely withdrawn). Daily visual spectrum images were calibrated to harvested biomass and used to assess biomass accumulation over the experiment. Image analyses were used to determine growth and senescence as functions of time and treatment, plant survival and to relate responses to geographical data. An accurate prediction of plant biomass (R²=0.92***) was made by comparing actual harvested biomass and projected shoot area. Dynamic responses in senescence between the multiple genotypes under the three treatments demonstrated stay-green and senescence responses were not associated with species. Microclimate/ geographical modelling indicated that origin of genotype was associated with drought tolerance and this helped explain the different responses within the same species. Water use efficiency (WUE), the amount of dry biomass accumulated per kg of water, correlated with summer rainfall. Phenomic analysis of drought responses was shown to have the potential to improve the selection of breeding candidates in Miscanthus and has identified interesting Miscanthus genotypes combining high biomass and high WUE for further characterisation.