Autotoxicity

Autotoxicity is a form of allelopathy in which a species inhibits growth or reproduction of members of that same species through the production of chemicals that are released into the environment.

This mechanism will result in reduced competition between members of the same species. Inhibition on the growth of other plants will increase the availability of nutrients.

In cultivation, autotoxicity can make it difficult or impossible to grow the same species after harvest of a crop. For example, this is known in alfalfa[1] and the tree Cunninghamia lanceolata[2] Other species displaying autotoxicity include the rush Juncus effusus[3] and the grass Lolium rigidum.[4]

In alfalfa

Autotoxicity in alfalfa is produced from the first seeding of the plant. The plant emits a chemical or chemicals into the soil that reduce the effectiveness of further alfalfa seedings. Studies show that the chemical is extractable from fresh alfalfa, is water-soluble, reduces germination, and prevents root growth.[5] Some believe that a chemical called medicarpin is responsible for autotoxicity. Roots of affected plants can be swollen, curled, discolored, and lack root hairs. Lack of root hairs reduces the plants ability to gather nutrients and absorb water.[6] Crop rotation is used to counteract autotoxicity in alfalfa.

References

  1. ↑ Chon, Su; Nelson, Cj; Coutts, Jh (Nov 2003), "Physiological assessment and path coefficient analysis to improve evaluation of alfalfa autotoxicity", Journal of Chemical Ecology, 29 (11): 2413–24, doi:10.1023/A:1026345515162, ISSN 0098-0331, PMID 14682523
  2. ↑ Kong, Ch; Chen, Lc; Xu, Xh; Wang, P; Wang, Sl (Dec 2008), "Allelochemicals and activities in a replanted Chinese fir (Cunninghamia lanceolata (Lamb.) Hook) tree ecosystem", Journal of Agricultural and Food Chemistry, 56 (24): 11734–9, doi:10.1021/jf802666p, ISSN 0021-8561, PMID 19053367
  3. ↑ Ervin, Gn; Wetzel, Rg (Jun 2000), "Allelochemical autotoxicity in the emergent wetland macrophyte Juncus effusus (Juncaceae)" (Free full text), American Journal of Botany, 87 (6): 853–860, doi:10.2307/2656893, ISSN 0002-9122, JSTOR 2656893, PMID 10860916
  4. ↑ Canals, Rm; Emeterio, Ls; Peralta, J (Aug 2005), "Autotoxicity in Lolium rigidum: analyzing the role of chemically mediated interactions in annual plant populations", Journal of Theoretical Biology, 235 (3): 402–7, doi:10.1016/j.jtbi.2005.01.020, ISSN 0022-5193, PMID 15882702
  5. ↑ Understanding Autotoxicity in Alfalfa, John Jennings, Extension Forage Specialist, University of Arkansas Cooperative Extension Service
  6. ↑ Alfalfa Autotoxicity, Joel Bagg, Forage Specialist, Ontario Ministry of Agriculture, Food and Rural Affairs, March 2001
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