A hydroponics experiment was conducted to evaluate the role of potassium (K) and silicon (Si) in mitigating the deleterious effects of NaCl on sugarcane genotypes differing in salt tolerance.Two salt-sensitive (CPF 243 and SPF 213) and two salt-tolerant (HSF 240 and CP 77-400) sugarcane genotypes were grown for six weeks in 1/2 strength Johnson's nutrient solution.The nutrient solution was salinized by two NaCl levels (0 and 100 mmol L 1 NaCl) and supplied with two levels of K (0 and 3 mmol L 1) and Si (0 and 2 mmol L 1).Applied NaCl enhanced Na + concentration in plant tissues and significantly (P ≤ 0.05) reduced shoot and root dry matter in four sugarcane genotypes.However,the magnitude of reduction was much greater in salt-sensitive genotypes than salt-tolerant genotypes.The salts interfered with the absorption of K + and Ca 2+ and significantly (P ≤ 0.05) decreased their uptake in sugarcane genotypes.Addition of K and Si either alone or in combination significantly (P ≤ 0.05) inhibited the uptake and transport of Na + from roots to shoots and improved dry matter yields under NaCl conditions.Potassium uptake,K + /Na + ratios,and Ca 2+ and Si uptake were also significantly (P ≤ 0.05) increased by the addition of K and/or Si to the root medium.In this study,K and Si-enhanced salt tolerance in sugarcane genotypes was ascribed to decreased Na + concentration and increased K + with a resultant improvement in K + /Na + ratio,which is a good indicator to assess plant tolerance to salt stress.However,further verification of these results is warranted under field conditions.
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