Allelopathy in wheat genotypes during the germination and seedling stages

Allelopathic effects of 10 wheat genotypes were studied in bioassays on germination and root length of lettuce. The germinating wheat seeds and seedlings of all genotypes inhibited the radicle elongation of lettuce. Excluding Secale cereale L., the inhibitory effects of wheat genotypes increased with wheat evolution history, as the genome changed from 2n to 4n to 6n. Allelopathic inhibition of different wheat genomes on lettuce radicles showed a decreasing trend of AABBDD > BB > AABB > RR > AA > DD. This suggests that the allelopathic genes may be located on genome BB and the allelopathic traits in the genomes may have evolved at different rates. The allelopathic effects of 10 spp. were correlated with age (20, 40, 60 d) of the seedlings. The allelopathic effects of different plant parts decreased in order aerial parts > whole plant > roots. A cluster analysis (Unweighted Pair Group Method using Arithmetic averages, UPGMA) was conducted for the allelopathic effect of 10 spp. at germination and seedling phases. In cluster analysis wheat spp. were divided into three categories based on their allelopathic effects on lettuce radicle. (a). Weak allelopathy: Triticum boeoticum L., French, Secale cereale L., Aegilops.tauschii Cosson Syn, Triticum dicoccoides K., Tritium aestivum L. Var. Shaan 160 and T aestivum Var. No.1 Ningdong. (b). Moderate allelopathy: Triticum monococcum L., Aegilops.speltoides L. and Triticum dicoccum S. and (c). Strong allelopathy: T aestivum Var. common wheat.