2.1 Waterlogging treatments
For experiment 1, a water tray was used to supply water to the bottom of each tank (Fig. 1). The water level of each container was maintained at 75 mm depth by fitting a float valve to a reservoir. Excess water from rainfall flowed back to the reservoir and out an overflow. Any water lost from the plant containers through evapotranspiration that reduced the water level below 75 mm was resupplied by the reservoir to maintain the water level. Control plots were watered near to field capacity until grain filling. Waterlogging was achieved by raising the reservoir above the soil surface such that the water level increased to 400 mm and the soil was completely saturated (lower panel in Fig. 1).
Waterlogging treatments for barley genotypes used in experiment 1 are shown in Table 2. Waterlogging treatment WL2 and a non-waterlogged control were conducted in experiment 2. For both experiments, the leaf number at which waterlogging was applied was measured on the main stem. After each waterlogging treatment concluded, treated plots were watered near to field capacity until grain filling, after which watering was ceased. Weed control was performed from emergence to harvesting by hand hoeing. No incidence of pest or disease infection were observed in either experiment.