Effect of chloride and sulfate salinity on nutrient uptake in Iranian rice (Oryza sativa L.)

摘要

Most of the studies on crops exposed to salinity stress under controlled in vitro conditions have used single salts only, usually NaCl. Studies involving the usage of natural salts mixtures of NaCl and Na_2SO_4 have been very few. Therefore a greenhouse experiment was conducted to determine the effects of both NaCl and Na_2SO_4 on mineral nutrient status of rice. Rice seedlings were hydroponically exposed to different salt concentrations and compositions for 21 days. The results revealed that only the root length was decreased by increasing salt level. The amounts of Na~+, K~+ and Mg~(2+) of shoot and root tissues increased at high salt levels. However Ca~(2+) content of root decreased with increasing salinity level. The Na~+/K~+ ratio was maintained in both shoot and root under salinity condition. An antagonistic effect between SO_4~(2-) and Ca~(2+) uptake was observed. A careful consideration of cation concentrations in shoots indicated that there is a gradual increase in Na~+ while K~+, Ca~(2+)and Mg~(2+) remained almost constant with salinity levels up to 5 dS/m. It is assumed that the composition of sodium salts plays a functional role in cationic balance within the Fajr genotype. As a conclusion the response of plant to salinity depends upon salt compositions.