Influence of fruit maturity and slimy seed coat on seed traits and germination of horned melon (Cucumis metuliferus E. Mey. Ex Schrad.)

In the past decade, there has been a significant rise in the consumption of wild collected horned melon (Cucumis metuliferus). Commercial production of the crop is growing, yet little information is available on its agronomy. Seed germination experiments were carried out at Midlands State University, to establish the effect of seed maturity at harvest, and the slimy seedcoat on germination of horned melon seed. Seed was manually extracted from fruit harvested at the mature green fruit (MG), colour break stage (CB) and fully ripe (FR) stage. Three replicates of fifteen seeds from each colour group were placed in petri dishes lined with cotton wool, wetted with distilled water and placed in an incubator at 25 °C. The petri dishes were arranged in a completely randomised design. The MG seeds showed 0% germination, whereas 13% of the CB seeds germinated by the end of the experiment. Seeds obtained from fully ripe (FR) fruits showed the highest germination rate (56%) (P < 0.05) and germinated in the shortest period. In the second experiment, seed harvested from the CB and FR stages were used, with one set of the seed having the slimy seedcoat removed and the second set having the slimy seedcoat intact. There was no significant interaction between seed harvesting stage and slimy seed coat removal (P = 0.331). However, removing the slimy seed coat significantly enhanced germination, with seeds lacking the coat showing 86.7% germination, 27.5% higher than those with an intact seed coat (59.2%) (P = 0.001). Removal of the slimy seedcoat improved seed germination in both the laboratory (P < 0.001) and greenhouse pot (P = 0.021) experiments. Significant germination improvement occurred when slimy seedcoat was removed.