The adaptation of some temperate agricultural, native and weed species to aluminium and manganese ions in acid soils

No study has defined how the comparative adaptation of agricultural and weed species to aluminium and manganese toxicity may influence plant competition in acid soils. Root growth data from glasshouse and laboratory investigations were used in a non-linear dose response model to define the relative tolerance of some common agricultural, native and weed species to toxic concentrations of aluminium and manganese ions. One ryegrass ecotype was highly tolerant to both toxicities, Austrodanthonia linkii was highly susceptible and several weed species were tolerant. In addition, a rapid bioassay procedure was developed and used to broaden the range of plant species/cultivars evaluated for plant tolerance to Ca2+, H+ and Al3+. Another glasshouse experiment demonstrated that annual ryegrass (Lolium rigidum) ecotypes taken from soil types that were either acid (pH 3.7, 2.34 µg/mL Al3+) or alkaline (pH 8.2, 0.01 µg/mL Al3+) regulated the level of their competition with sensitive phalaris (cv. Sirolan, suppressed) or tolerant cocksfoot (cv. Porto, not suppressed). These results indicated the potential difficulty of establishing a sensitive plant type on acid soils if an adapted competitor also is present as a weed.