4.1. Plant Material and Flooding Treatments

A commercial spring wheat (Triticum aestivum L.) variety Efumai 1 was used in this study. Seeds of Efumai 1 were surface-sterilized with 2% sodium hypochlorite for 15 min and rinsed with deionized water three times. The seeds were then planted in growth pots (6 plants in each pot), filled with the same amount of soil, and placed in a greenhouse with a 14 h/10 h and 22 °C/18 °C day/night and light/temperature cycle. Relative humidity was maintained at 70%. Six pots were established for each replicate. After 18 days of growth (at the stage with three fully expanded leaves), uniform seedlings were kept and divided into four groups, including the CK and three flooding treatments. The three types of flooding stress treatments were designed based on the depth of the water table, described as waterlogging (WL: keeping the water level at the surface soil level ±1 cm), half submergence (HS: keeping the water level at half of the plant height), and full submergence (FS: keeping the plant fully submerged). For the control, the seedlings were grown in ideal conditions. A completely randomized design with three biological replicates was applied in this experiment.