Amelioration of Salt Stress in Sugarcane ( Saccharum officinarum L.) by Supplying Potassium and Silicon in Hydroponics

Abstract

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 ½ 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.