Salt-Induced Damage to Rice Plants and Alleviation Effect of Silicate

Rice plants were grown hydroponicaIly in the presence of either NaCI, sea water, or polyethylene glycol (PEG: average molecular weights of 7,800–9,000) at an osmotic potential of up to 186 mOsmol/kg, equivalent to 100 mM NaCI or 20% sea water, and the growth and mineral composition of the plants were compared. NaCI was the most detrimental agent, followed by sea water and PEG. Mineral contents, including nitrogen, phosphorus, potassium, and calcium were not significantly affected by the treatments. Removal of silicate from the culture solution brought about a more severe growth reduction in rice plants subjected to 100 mM NaCI stress. In the plants which received silicate, the contents of sodium in the shoots were nearly half of those in the shoots of plants which did not receive silicate.