Drought tolerance in perennial ryegrass (Lolium perenne L.) asassessed by two contrasting phenotyping systems

The objectives of this research were to establish a practicable phenotyping platform for assessing the drought stress response of perennial ryegrass (Lolium perenne L.; Lp), and to use this platform for evaluating the variation for drought tolerance among a panel of 39 diverse Lp populations. A moderate-to-strong correlation was assessed between the performance of plants grown in a hydroponics system, where the stress was generated by the addition of polyethylene glycol (PEG), and those grown in the field in a rainout shelter. Following the application of drought stress, tetraploid Lp populations, along with a small number of reference Festulolium and Festuca sp. accessions, were able to develop more shoot and root dry matter than diploid Lp populations. The onset of drought symptoms was also delayed within these accessions and the plants recovered better once drought had been relieved. Although most of the diploid Lp populations were drought susceptible, there was a considerable accession-to-accession variation for performance under drought stress conditions. Measuring biomass production and post-drought recovery in rainout shelter experiments in combination with the assessment of root biomass accumulation in PEG-supplemented hydroponics represented a viable means of screening Lp germplasm for drought tolerance.