Drought is a complex stress which elicits a wide variety of plant responses. As such, genetic studies of drought are particularly difficult. Elucidation of the genetic basis of components contributing to drought tolerance is likely to be more tractable than that of overall drought tolerance. Certain of the traits which contribute to drought tolerance in plants and the high-throughput phenotyping techniques available to measure those traits are described in this paper. Given the dynamic nature of drought, plant development and the resulting stress response, the focus is on non-destructive imaging techniques which allow a temporal resolution and monitoring of the same plants throughout the experiment. Information on the physiological changes in response to drought over time is vital in order to identify and characterise different drought tolerance mechanisms. High-throughput imaging provides a valuable new tool which allows the dissection into a series of component traits of plant responses to drought. Ten barley lines used as parents of mapping populations or for the generation of transgenic plants were compared for their behaviour under drought. The barley lines were grown under two stable watering regimes - well watered and -5 bar of soil water potential. The low watering treatment was started 30 days after planting. All plants were imaged and watered every second day from day 30 to day 70 after sowing. Six replicates for each line and treatment were used. Leaf area was determined from a calibration curve between imaging variables and true leaf area measured destructively on two wheat genotypes and a barley line. Kinetics of leaf area were modelled with 3 parameters: final leaf area, relative growth rate (RGR), and time of inflexion point (time at which the growth rate starts to decrease, considered as a shift between vegetative stage and reproductive stage).
The experiment was funded by ACPFG and carried out between 2010-10-15 and 2010-11-24