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.