Seed Treatment to Improve Water Imbibition and Germination of Pomegranate (Punica granatum)

Pomegranate (Punica granatum) is one of the oldest known edible fruits used by the African indigenous people for a long time. It plays an important role in the nutritional security, of especially, poor households within Southern Africa. Its significance, both as a dietary supplement and medicine, has recently gained ground due to the realisation of its high antioxidant and phytochemical contents. P. granatum fruits have a good prospect for local and international commercial markets. However, its propagation and seedling availability is fraught with difficulties because the hard seed coat strongly resists entry of water and gaseous exchange. This study investigated techniques of scarifying the seeds to break dormancy and enhance germination and seedling establishment. The treatments consisted of a combination of two pre-germination seed condition (fresh and dry) and nine pre-sowing seed treatments (control, hot water-10 and 30 min, sulphuric acid-10 and 30 min, gibberrelic acid-24 h and 10 min, sandpaper and scalpel). Thirty treated mature seeds were germinated on moist filter paper in a petri dish at 35 degrees C using a completely randomised design with four replicates. The ANOVA showed significant effects of both seed condition and treatments on water imbibition and germination. Dry seeds had significantly higher (P<0.05) water imbibitions (9.6 vs. 17.8 mm h(-1)) and germination (25.3 vs. 67.8%) than fresh seeds. The improvements were in the order: acid>hot water>gibberrelic acid>sandpaper>scalpel>control. Similar trends were observed for seed germination rates. A significant correlation (r=0.83, p<0.01) between water imbibitions and seed germination implies that the seed treatments enhanced both water imbibitions and germination processes. The fleshy pulp surrounding the fresh seeds was considered to have reduced its ability to imbibe water for germination. It was concluded that potential exists for promoting the propagation and cultivation of the P. granatum fruit trees through mass production of seedlings using the most efficient seed treatments to break dormancy.