Autotoxicity of chard and its allelopathic potentiality on germination and some metabolic activities associated with growth of wheat seedlings

In this study, the alleiopathic effect of aqueous whole mature chard plant extract (Beta vulgaris L. var. Cicla) on wheat (Triticum vulgare L. var. Sides 1) and an associated weed (chard) was investigated. Plants used were sampled in 2006, and then plant extracts were obtained after they were ground and processed with distilled water. Twenty five of wheat grains and the same number of chard seeds of uniform size and weight were placed in a mixture on sterile filter paper in 15 cm Petri-dishes. Treated Petri-dishes were each supplied with 20 ml extract of 0.25, 1, 4, 8, and 12% (w/v) while untreated control was supplied with 20 ml of distilled water. After 10 days the germination percentage, vigour value, seedling growth criteria and some physiological processes were counted. The aqueous extract retarded the germination of chard more effectively than that of wheat and the effect was concentration dependent. The lowest concentration stimulated the germination of both wheat and chard; on the other hand, the germination was retarded under the application of concentrations above 1%. However, 1% concentration had a positive effect on wheat and negative on chard. HPLC analyses of the water-soluble extract of whole chard plant residue revealed the presence of eight phenolic aglycones that show the abundant of chichimec acid, (+) camphor, hydroxybenzoic, p-coumaric and vanillic acids as well as trace amounts of coumarin and protocatechuic acids. This extract may be used as a bioherbicide to control the germination and growth of itself (autotoxicity).