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United States Department of Agriculture

Agricultural Research Service

Title: Osmotic and Allelopathic Effects on Germination and Seedling Growth of Legumes by Tall Fescue

Author
item Springer, Timothy

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 24, 1996
Publication Date: N/A

Interpretive Summary: The biochemical interaction between plant species, known as allelopathy, can influence pasture diversity and possibly the field persistence of some forage legumes. An investigation was conducted to determine the allelopathic effects caused by aqueous seed extracts of endophyte-free or -infected tall fescue on the seed germination and seedling growth of ball, crimson, red, subterranean, and white clover. Sterile water extracts were prepared of the tall fescue and each of the clover species were germinated in the extracts. Seed germination was slightly reduced by tall fescue extracts. Root morphology was affected more by extract solution than other seedling characters. Allelopathic effects were enhanced by the presence of the endophyte. Allelochemicals produced by fungal endophytes significantly affected seedling roots lengths, root hairs lengths, and root hair densities. Allelopathy is known to affect the spacing of herbaceous plants, as well as, their morphological characteristics. Legumes with weakened root system may be more susceptible to disease and/or insect attacks, and plants with smaller root systems may not be able to store sufficient carbohydrates to over winter or for regrowth.

Technical Abstract: Allelopathy can influence the botanical composition and possibly the field persistence of some forage legumes. The objectives were to investigate osmotic and allelopathic effects caused by aqueous seed extracts of endophyte-free (TF-E-) or -infected (TF+E) tall fescue on the seed germination and seedling growth of five legumes. Significant differences (P<0.05) occurred among species for percentage seed germination in deionized water. Variation in osmotic effects, germination in extract solutions and allelopathic effects were only attributed to species differences. The germination of ball clover, red clover, and white clover were significantly reduced by the osmotic potential of the extract solutions. However, stimulatory allelopathic effects for these species overcame the osmotic effects. Root morphology was affected more by extract solutions than other seedling characters studied. Allelochemicals produced by fungal endophytes significantly affected seedling roots, and significant differences in the lengths of seedling roots, root hairs, and root hair densities were observed between TF-E and TF+E extracts. Legumes with weakened root system may be more susceptible to disease and/or insect attacks, and plants with smaller root systems may not be able to store sufficient carbohydrates to over winter or for regrowth.

Last Modified: 12/17/2014
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