Abstract: For overcoming germination barriers of triploid watermelon seeds, six cultivars of triploid watermelon seeds were designed to hydropriming by soaking in 0.1% H2O2 aerated water or water for 2 h following 24 h, 34 h and 48 h of incubation at saturated relative humidity. Germination viability and seedling growth rate of the seeds significantly increased by 38%-56% in hydropriming treatments. The germination percentage of the six cultivars increased in various degrees from 14% to 66% according as different cultivars. The 34 h and 48 h of incubation hydropriming combined with H2O2 treatment showed the best result. The beneficial effects of hydropriming were maintained as dehydration after primed seeds were redried to original moisture content and stored. The investigation of seed and embryo structure with soft X-ray indicates that germination barriers of triploid watermelon are seedcoat related, and that hydropriming can overcome these barriers.

Key words: Triploid watermelon (seedless watermelon), Hydropriming, Germination percentage, Seed structure