Responces of Typha domingensis to salinity and high levels of maganese in the rooting medium

Abstract

The response of T. domingensis, a large emergent macrophyte, to salinity and manganese was studied under glasshouse conditions. Plants were grown in saline solutions ranging in concentration from 0.5 to 100 mM NaCI. and in manganese sulfate solutions ranging in concentration from 0.01 to 10 mM.

Growth was reduced slightly at 50 mM NaCl and severely at 100 mM NaC1, suggesting that T. domingensis is moderately salt tolerant. Plant parts had highest chloride levels at 25 mM NaCl and highest sodium levels at 100 mM NaCl. The highest sodium chloride treatment reduced the level of potassium in the rhizomes, but not in roots or leaves. Sodium chloride had no effect on the concentration of nitrate in organs, but total nitrogen levels in roots and rhizomes increased at 100 mM NaCI. Sodium was considered to be more toxic than chloride.

Growth in manganese solutions was unaffected except at the highest concentration used. Manganese accumulated quickly in leaves to levels which would be toxic to livestock; leaves retaining over 70% of the total manganese in the plant. Manganese applied at high concentrations substantially reduced the levels of calcium, magnesium and phosphorus in the leaves.

In a field experiment, there were seasonal changes in the levels of selected elements in the leaves of T. domingensis. During leaf senescence. concentrations of sodium, manganese and calcium increased by 20-80%, but levels of phosphorus, nitrogen, potassium and maganesium fell by 65-84%. The results are discussed in relation to the use of T. domingensis in Hastewater reclamation.