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The relative tolerance of balansa and sub clovers, murex medic and lucerne to aluminium and manganese

D.G. De Marco, P.J. Randall and S.P. Mills

CSIRO Division of Plant Industry, PO Box 1600, Canberra ACT 2601

Balansa, Trifolium balansae, and murex, Medicago murex, are recently commercialised pasture legumes suitable for the >500 mm rainfall zone of south-eastern Australia. As the soils of the region are amongst the most prone to acidification, it is important that the acid soil tolerance of these species be established. Evans et al. (1) showed balansa and murex to be similar to each other but inferior to sub clover, Trifolium subterraneum, in tolerance to soil acidity. We report on the relative tolerances of four pasture legume species to Al and Mn, two of the major factors of the soil acidity complex.


Four species (Table 1) were assessed for Al tolerance in solution culture (dilute nutrient pH 4.1 at 0, 10, 20, 40, and 80uM Al) and for Mn tolerance in sand culture (pH 5.6 with 0.01, 0.25, 0.5, 1mM Mn). Plants were supplied with mineral nitrogen to avoid complications arising from effects on the symbiotic system.

Results and discussion

Sub clover was the most tolerant to both Al and Mn, lucerne, Medicago saliva, was the least tolerant and balansa and murex were intermediate (Table 1)

Table 1. Effect of Al and Mn on shoot yield of sub clover cv. Mt Barker, balansa cv paradana, murex cv Zodiac and lucerne cv Siriver. Values are percent of control.

For both shoot and root growth balansa was better than murex at low Al but the difference disappeared or was reversed at higher Al. Root extension virtually ceased when Al concentra- tion exceeded 10uM for lucerne, 40uM for balansa and murex and 80uM for sub. The clovers were more tolerant to manganese than the medics, particularly at the highest level. From this work and that on the associated rhizobia (2), murex is clearly more tolerant of soil acidity than lucerne. It should be noted that these species rankings are based on only one cultivar.


The work was supported by the Wool Research and Development Council.


Evans, J., Dear, B., and O'Connor, G.E. 190. Aust. J. Exp. Agric. 30, 55-60. Howieson, J.G. and Ewing, M.A. 1986. Aust. J. Agric. Res. 37, 55-64.

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