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

Orobanche minor seed only germinates when germination stimulants from host plants or some non-hosts become available. Wheat has been reported as a trap crop to stimulate O. minor germination. Wheat at different ploidy levels were evaluated for their impacts on O. minor germination. The results that wheat exudates collected hydroponically induced O. minor germination. Wheat at 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 activitiy at one mg/L concentration. Similarly, the stimulation of O. minor germination was dependent 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 at the tillering stage with hexaploid T. aestivum var. Shaan No. 253, while the lowest rate (4.2%) was at maturity stage with diploid T. boeoticum L. Plant methanolic extracts resulted in higher O. minor germination than the aqueous extracts. This study suggests that wheat accessions of different ploidy levels differ in their allelopathic stimulation on O. minor germination and the stimulation increases from diploid to hexaploid. These results indicate that wheat allelopathic activity could be used as a non-chemical option for O. minormanagement