MINERAL IMBALANCE DUE TO MANGANESE EXCESS IN TRITICALES

Abstract

Acid soils, which represent a large fraction of arable soils in the world, frequently have an excess of available aluminum (Al) and manganese (Mn). In such problem soils, plant genotypes with a higher degree of tolerance to low pH and or an excess of these minerals are recommended. In previous works cereal triticale demonstrated considerable tolerance both for Al and Mn excess, but with a large variability among cultivars (cvs.). This article extends the evaluation to other cvs. and discusses the contribution of changes in mineral uptake and translocation to the growth inhibition in cases of Mn excess. Plants of nine cvs. of triticale and one of wheat were submitted to a range of Mn concentrations from 2.5 to 50 mg l⁻¹ and growth evaluated through dried biomass, both in the vegetative stage after 1 month of growth and after the filling of the grain. Mineral analysis that included nitrogen (N), potassium (K), phosphorus (P), calcium (Ca), magnesium (Mg), iron (Fe), zinc (Zn), and Mn was conducted on the dried plant material. From the growth inhibition we concluded that the cvs. Juanilho, Borba, TTE 9201 and BH 1146 (wheat) are more tolerant and that the cvs. Arabian, Beagle, TTE 9101, and TTE 9203 are more sensitive. The capacity to reduce the Mn uptake and therefore to avoid very high tissue concentrations in the leaf could be a strategy contributing to a higher tolerance in TTE 9201 and wheat BH 1146. Significant decreases in Ca and Mg and increases in Zn were observed. Also a good correlation between the Mg:Mn ratio and the relative growth envolving all the cvs. was observed.

ACKNOWLEDGMENTS

The authors are grateful to Dr. J. C. Ramalho for useful discussions and to Estação Agronómica Nacional for several experimental facilities. Financial support was given by PRAXIS 3/3.2/AGR/2184/95.