Efficient Mn uptake in barley is a constitutive system

Mn-efficient barley genotypes can absorb more Mn from soil than Mn-inefficient genotypes. To examine whether this capability is induced only under Mn deficiency, two barley genotypes differing in Mn efficiency were grown in a calcareous soil supplied with Mn from 0 to 1000 mg kg soil-1. Results showed that the efficient Mn uptake system in the Mn-efficient genotype functioned over the full range of Mn supply, and thus it is concluded that the efficient Mn uptake is a constitutive system.