Differences in Autotoxicity among Seven Alfalfa Cultivars
- Min Chung and
- Darrell A. Miller
There is a need to determine if alfalfa (Medicago sativa L. subsp. sativa) can be selected for low concentrations of allelopathic compounds. The objective of this study was to evaluate alfalfa cultivar differences in autotoxic traits in relation to various concentrations of aqueous extracts. Plant extracts from seven alfalfa cultivars (Apollo-Supreme, Arrow, Vernal, DK-125, Dawn, Pioneer 5472, and Magnum III) were evaluated in the laboratory for autotoxic effects on the same cultivar at four levels of extract solution (10,20,30, and 40% w/v). Double-distilled water was used as a control. Germination percentage, seedling length, and seedling dry weight were measured to determine the effect of the same cultivar extracts on alfalfa growth. These parameters were significantly reduced as the extract concentration increased. The highest concentration (40%) caused the greatest reduction in hypocotyl and radicle length, seedling dry weight, germination percentage, and seedling vigor in all cultivars. It also significantly increased the time required for germination. Autotoxicity effects were significantly different among the various cultivars. Cultivars may be classified in the following order of decreasing inhibition: Pioneer 5472, Arrow, Magnum III, Vernal, Apollo-Supreme, DK-125 and Dawn. The results indicate that there may be genetic differences among cultivars for resistance to alfalfa autotoxicity, and that selection for low autotoxicity may be possible.
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