Abstract

ACCIARESI, Horacio A  and  ASENJO, Carlos A. Allelopathic effects of Sorghum halepense (L.) Pers. on Triticum aestivum (L.) seedlings growth and above-ground and below-ground biomass. Ecol. austral [online]. 2003, vol.13, n.1, pp.49-61. ISSN 1667-782X.

Allelopathic effects of four Sorghum halepense populations on both seedling growth and above-ground and below-ground biomass of wheat (Triticum aestivum) varieties after 50 and 90 days of soil decomposition were studied. Weed rhizomes from four Argentinean sites (Rufino, Rojas, Paraná, and 9 de Julio) were collected. Aqueous extracts of the rhizome residues were tested for phytotoxicity to radicle growth and coleoptile growth of four early wheat varieties and four late wheat varieties. Two container experiments were conducted simultaneously to determine the allelopathic potential of weed soil rhizome residues on above-ground and below-ground biomass of wheat varieties. Early and late wheat cultivars were affected by the aqueous extract from the four Sorghum halepense sites, showing Rufino the greatest inhibitory effect. The radicle growth was more depressed than coleoptile growth. The above-ground and below-ground biomass of early wheat varieties were diminished by the soil residues of the four weed origins, while only Rufino residues exerted inhibitory effects on wheat late varieties. For late cultivars significant origin x variety interactions were obtained, showing that late cultivars response varied depending on the sites studied. The lowest rainfall during weed growing cycle could explain the highest inhibitory effect of Rufino residues. This less optimal growth condition could have maximized allelochemical concentrations in these residues. This study demonstrates that under restricted conditions the potential exists for inhibiting wheat seedling growth and above-ground and below-ground crop biomass, but also indicates that weed origins and crop varieties need to be factored in modifying allelopathic responses in field conditions.

Keywords : Allelopathy; Johnsongrass; Rhizome residues; Wheat varieties.

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