Rice growth in a combined submergence and salinity stresses

The occurrence of submergence in agricultural land is increased by the climate change. The level of tolerance in crops depends on many factors including plant stages, duration of submergence. Level of crop tolerance to submergence is likely to decrease when other adverse factors such as salinity exist. Two experiments have been conducted to study the effect of a combined submergence and salinity on rice growth. First experiment studied the salt tolerance at early seedling stage while submerged. Split plot design was used with oxygen concentrations (with and without aeration) as the main plot and salinity levels (0.2, 50, 100 dan 150 mM NaCl) as the sub plot. Second experiment evaluated the length of submergence (one and two weeks) and salinity levels (0.2 and 50 mM NaCl) at older stages rice plants. The results showed that at early stages of seedlings, almost all growth variables have been decreased by salinity. The oxygen deficit reduced salt tolerance in rice seedlings. At older stages of rice, one-week submergence did not reduce rice growth. However, for two weeks submergence, rice submerged in saline water showed better growth compared to those submerged in non-saline water.