Allelopathic stimulatory effects of wheat differing in ploidy levels on Orobanche minor germination

Orobanche minor seed germinates only when germination stimulants from host plants or some non-hosts become available. Wheat is trap crop to stimulate the O. minor germination, hence, wheat of different ploidy levels were evaluated for their impacts on O. minor germination. The wheat exudates collected hydroponically induced the O. minor germination. Wheat of different ploidy levels differed in their allelopathic stimulation on O. minor germination, with the hexaploid wheat being the most stimulatory. Root exudate activity was concentration-dependent, with no activity at 1 mg/L concentration. Likewise, the stimulation of O. minor germination also depended on wheat ploidy level, the growth stage and the concentrations of aqueous or methanolic extracts. The highest germination (41.6%) was achieved with aqueous extracts from the tillering stage with hexaploid T. aestivum var. Shaan No. 253, while the lowest rate (4.2%) was from maturity stage with diploid T. boeoticum L. Plant methanolic extracts resulted in higher O. minor germination than aqueous extracts. Thus wheat accessions of differed ploidy levels differed in their allelopathic stimulation of O. minor germination and the stimulation increased from diploid to hexaploid. The wheat allelopathic activity could be used as a non-chemical option for O. minor control.