Publication Date

1985

Location

Kyoto Japan

Description

Four tropical pasture legumes, Macroptilium atropurpureum, Stylosanthes humilis, Desmodium intortum and Centros­ema pubescens and a temperate pasture legume, Trifolium repens were grown at the graded levels of Al concentration in a culture solution in order to examine the effects of Al on their growth and N2-fixing activities (CzH2 reduction). In a separate experiment, two tropical pasture legumes, M. atropurpureum and C.pubescens dependent upon combined-N or symbiotically fixed-N were subjected to the graded levels of Al concentration and their dry weight, Nz-fixing activities and root length were measured. The results obtained are as follows.

1) The tolerances to Al in terms of the relative weight received Al to none received were in the order of M.atropurpureum = S.humilis = C. pubescens > D.intortum > T.repens.

2) The critical concentration of Al with respects to N2-fixing activities was about 20ppm in some tropical legumes except M. atropurpureum, in which as much high as lOOppm of Al concentration in solution culture had none of adverse effects on N -fixing activity.

In M.atropurpureum, even 20ppm Al decreased the total root length and increased the root thickness whereas in C.pubescens, at above that level of Al, its total root length and root thickness were affected to a smaller extent


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Effects of Al Concentration in Culture Solution on the Growth and N2 Fixation of Some Tropical Pasture Legumes

Kyoto Japan

Four tropical pasture legumes, Macroptilium atropurpureum, Stylosanthes humilis, Desmodium intortum and Centros­ema pubescens and a temperate pasture legume, Trifolium repens were grown at the graded levels of Al concentration in a culture solution in order to examine the effects of Al on their growth and N2-fixing activities (CzH2 reduction). In a separate experiment, two tropical pasture legumes, M. atropurpureum and C.pubescens dependent upon combined-N or symbiotically fixed-N were subjected to the graded levels of Al concentration and their dry weight, Nz-fixing activities and root length were measured. The results obtained are as follows.

1) The tolerances to Al in terms of the relative weight received Al to none received were in the order of M.atropurpureum = S.humilis = C. pubescens > D.intortum > T.repens.

2) The critical concentration of Al with respects to N2-fixing activities was about 20ppm in some tropical legumes except M. atropurpureum, in which as much high as lOOppm of Al concentration in solution culture had none of adverse effects on N -fixing activity.

In M.atropurpureum, even 20ppm Al decreased the total root length and increased the root thickness whereas in C.pubescens, at above that level of Al, its total root length and root thickness were affected to a smaller extent