Effects of silicon on growth and potassium transport in triticale and rye exposed to aluminium and nitrite stress

The objective of this study was to examine the dual effects of Al3+, NO2− and Si on the growth (DW) and potassium transport of roots in a moderately Al-sensitive triticale (xTriticosecale Wittmack cv. GK Marko) and in an Al-tolerant rye (Secale cereale L. cv. GK Wibro) seedlings. Plants were grown in 0.5 mM CaSO4 solution at pH 4.1 or 6.5 with different levels of AlCl3, NaNO2 and Na2SiO3. Increased levels of Al in the solution reduced root growth in order of Al-tolerance of species (rye>triticale). Shoot growth was only moderately influenced at higher Al concentration in triticale. Si in the growth solution enabled plants to overcome Al toxicity symptoms, however, a genotypic difference was found in response of cereal species to Si applications. Triticale proved to be more sensitive to Al and Si treatments then the rye seedlings. In short-term (6h) potassium uptake experiments, Si reduced the stimulatory effect of Al on K+(86Rb) influx in roots which indicates a definite Al + Si interaction at the plant level. In case of nitrite ion alone and in Al + nitrite combinations, a striking inhibition was experienced in K+(86Rb) influx of roots in both species, which was not significantly influenced by addition of Si. K+(86Rb) efflux from roots of triticale was always higher then in case of rye. The results of short-term potassium uptake suggest that Si in combination with Al and NO2− interfere with the membrane transport processes of plants.