Hypoxis hemerocallidea seed germination: a journey of investigation

Effective propagation systems are needed to ensure a sustainable supply of quality plant material for the commercialization of any natural product. The seeds of Hypoxis hemerocallidea, although abundant, are notoriously difficult to germinate. Several researchers have published on the subject and reported on dormancy and how it effects germination, but when trying to produce from seed, using successful reported methods results remain inconsistent. The effect of seed age (fresh, one and two-yearold) and various pre-sowing seed treatment methods (hot water treatments, for different durations; microwave treatment for different durations; 1200 ppm GA(3) & 4% KNO3) to overcome dormancy were thus investigated together with seed histology. Seed were germinated in Petri-dishes on moist filter paper at 25 degrees C in growth chambers and germination percentage, mean germination time and GT(50) values were calculated. A randomized complete block design was used with four replicates. The very hard, brittle and thick seed coat of H. hemerocallidea made it difficult to obtain clear histological slides. The seed embryo however, enlarged with time as older seed had larger embryo sizes. The seed furthermore have an operculum and emergence of the radicle only takes place when the operculum opens. The highest average germination percentage (34%) was achieved with seeds that were pre-treated with a 15 s microwave treatment. Seed age had no effect on the germination percentage. The seed, however, seems to have a strong circadian clock and various treatments (including the control) led to germination ( as high as 80%) when applied during late spring and early summer. The same treatments applied during other times of the year, did not result in germination or germination percentages of below 5%. This observation warrants further investigation into the timing of germination and would explain the inconsistent germination observed during attempts to germinate seed on large scale.