Germination of Orobanche crenata Forsk. seeds in vitro

The effects of calcium hypochlorite Ca(OCl)₂] and gibberellic acid (GA), both in combination and separately, were studied on the germination of Orobanche crenata seeds. Hypochlorite was applied either before or after the conditioning phase for periods up to 150 min. The seeds were exposed to GA during the conditioning phase. After conditioning the seeds were exposed to either the synthetic germination stimulant GR 7, flax root exudate (FRE) or distilled water. GR 7 exploited the germination potential of O. crenata better than FRE and this in turn better than water. In the presence of GR 7 or FRE the number of germinating seeds generally increased when the seeds were briefly (5–20 min) exposed to hypochlorite. In the absence of GR 7 and FRE, hypochlorite only increased germination if the seeds were treated during medium-long periods (20–60 min) after conditioning. If GR 7 or FRE were not applied the germination percentage was usually significantly higher when conditioning was done in the presence of GA.