The allelopathic potential of alfalfa root medicagenic acid glycosides and their fate in soil environments |
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Authors: | W Oleszek M Jurzysta |
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Institution: | (1) Institute of Soil Science and Plant Cultivation, PL-24-100 Pulawy, Poland |
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Abstract: | Summary The allelopathic effect of alfalfa (Medicago media Pers.) and red clover (Trifolium pratense L.) root saponins on winter wheat seedling growth and the fate of these chemicals in soil environments were studied. Seed
germination, seedling and test fungus growth were suppressed by water and by alcohol extracts of alfalfa roots, and by crude
saponins of alfalfa roots, indicating that medicagenic acid glycosides are the inhibitor. Powdered alfalfa roots inhibited
wheat seedling growth when added to sand. At concentrations as low as 0.25% (w/w) the root system was completely destroyed
whereas seedling shoots suffered little damage. Red clover roots caused some wheat growth inhibition when incorporated to
sand, but their effect was much lower than in the alfalfa root treatment.
Soil textures had a significant influence on the inhibitory effect of alfalfa roots. The inhibition of seedling growth was
more pronounced on light than on heavy soils. This was attribted to the higher sorption of inhibitors by heavy soils.
Incubation of alfalfa roots mixed into loose sand, coarse sand, loamy sand and clay loam for a period of 0–8 days resulted
in decreased toxicity to bothT. viride and wheat seedlings. This decrease occurred more quickly in heavier soils than in loose sand, due to the hydrolysis of glycosides
by soil microorganisms. Soil microbes were capable of detoxifying medicagenic acid glycosides by partial hydrolysis of sugar
chain to aglycone.
These findings illustrate the importance of medicagenic acid glycosides as an inhibitor of wheat seedling growth, and of their
fate in different soil environments. |
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Keywords: | Allelopathy Detoxification Medicago media Pers Root saponins Trifolium pratense L |
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