Effects of chloride and sulfate application on root growth of rice

In several studies, the beneficial effects of the application of chloride on root growth have been reported. However, the effect of chloride application on the morphology of roots has not been studied extensively. The effects of the use of chloride salts and sulfate salts on the growth of rice (Oryza sativa L.) until the 7-leaf stage were investigated in soil and water culture experiments. In the soil culture experiments, the root biomass in the chloride treatment showed a 58% increase compared with the sulfate treatment. Total root length, top root ratio (T / R ratio) and root length per primary root revealed the existence of root growth promotion by chloride. In the water culture experiments, root growth was also stimulated by chloride, as in the soil culture experiments. In order to analyze the effect of chloride application, the ion composition and pH of the soil solution or water culture solution were used to determine the amounts of ion species in the solution using the MINTEQA2 computer program, and the results were applied to estimate the osmotic pressure of these solutions. The osmotic pressure of chloride salts was obviously higher than that of sulfate salts based on van't Hoff's law of osmotic pressure and a positive correlation between the osmotic pressure and root length was obtained. The results suggest that the higher osmotic pressure induced by chloride would be involved in the root growth promotion of rice.