Determination of allelochemicals in spring cereal cultivars of different competitiveness

Abstract

Competitive cereal cultivars are less susceptible than others to weed interference. Their characterization may provide selection criteria that can be used as guidelines to develop new, even more competitive cultivars. Root exudates are a potential means by which competitive cultivars reduce weed growth. The objectives of this study were to evaluate the effect of cereal root exudates onBrassica kaber(DC.) L. C. Wheeler growth, to isolate and characterize the allelochemical compounds released by spring cereal cultivars, and to determine if a relation exists between these allelochemicals and cultivar competitiveness. Highly competitive (HC) and lesser competitive (LC) cultivars of four crop kinds (Triticum aestivumL. [wheat],Avena sativaL. [wild oat], two- and six-rowedHordeum vulgareL. [barley]) were selected based on previous work. Exudates from undisturbed root systems ofB. kaberand cereals were collected and used in a bioassay test withB. kaber.Root exudates were analyzed for 16 common phenolic compounds using high-performance liquid chromatography (HPLC). Bioassays indicated that cereal exudates had no negative effect onB. kabergermination, but all concentrations of cereal root exudates inhibitedB. kaberroot and hypocotyl growth. As cereal root exudate concentration increased,B. kabergrowth decreased. For each crop kind,B. kabergrowth inhibition was greater with HC cultivars than with LC cultivars. The root exudates of all crop kinds and cultivars contained benzoic, caffeic, ferulic,o-coumaric, and vanillic acids as well as scopoletin. Para-hydroxybenzoic acid was found in exudates fromT. aestivum, A. sativa, and two-rowedH. vulgarecultivars. Para-coumaric acid was not identified in root exudates from LCH. vulgarecultivars. Gentisic acid was produced byA. sativaandH. vulgare.Vanillic ando-coumaric acids along with scopoletin may be responsible for the allelopathic effects ofH. vulgare, T. aestivum, andA. sativacultivars. These three compounds may be useful as possible indicators of allelopathic potential of genotypes under development and thus considered for use in breeding programs.

Bioassay-guided isolation of allelochemicals from Avena sativa L.: allelopathic potential of flavone C-glycosides

“…In conclusion, our results provide strong evidence of the allelopathic potential of oat biomass due to flavonoid compounds in accord with recent literature data reporting allelopathic activity for phenolic compounds in oats (Baghestani et al 1999;Chon and Kim 2004;Hura et al 2006). …”

Isolation of bioactive allelochemicals from sunflower (variety Suncross-42) through fractionation-guided bioassays

“…Positive effects of allelochemicals could be related to the ability of some plants to exploit allelochemicals as a source of nutrition at low concentration (Baghestani, Lemieux, Leroux, & Simard, 1999). Rice (1984) has suggested that such stimulation might not originate from the allelopathic compounds but might instead be due to an improvement of the growing substrate because of the organic matter enrichment.…”

Electrochemical behavior of caffeic acid at single-walled carbon nanotube:graphite-based electrode

“…Many biological activities have been reported for free caffeic acid (CA) [12][13][14][15][16][17][18][19]. In several plant species, the levels of caffeic acid and other phenolics appear to be related to pest resistance [20][21][22].…”