Nutrient conditions and waterlogging
The nutrient solution was after (Cui et al. , 2019a), where the amount of K+ was varied by changing the amount of KCl. Two K availability conditions were used here: “low K” (0.2 mM) and “high K” (4 mM). The amount of nitrate and phosphate (in mM) in the nutrient solution was kept constant throughout experiments (nutrient solution composition in Table S1). Nitrate concentration of the nutrient solution was 15 mM to cover plant N needs and avoid any N-limitation effects. The amount of Ca2+ (low [0.4 mM], and high [4 mM]) was adjusted my changing the balance between Ca-nitrate and Na-nitrate (Table S1). Putrescine was added at a concentration of 0.4 mM. Taken as a whole, there were six nutrient conditions: low K and high Ca (LK-HCa), high K and high Ca (HK-HCa), low K and low Ca (LK-LCa), high K and low Ca (HK-LCa), low K and high Ca with putrescine addition (LK-HCa+P), and high K and high Ca with putrescine addition (HK-HCa+P). It should be noted that here, the condition low Ca + putrescine (under either low or high K) has not been used because the objective was to assess whether putrescine addition can compensate for the effects of high Ca. In figures, high Ca, low Ca and high Ca + putrescine conditions are shown with blue, green and pink shades, respectively.