What was compared
Jara-Peña, Quiroz and Vela Arce collected seeds of fourteen taxa from four departments of Peru. Each species was subjected to two treatments, a cycle of 12 hours of light and 12 hours of darkness, and continuous darkness. Each treatment comprised five dishes, each with 25 seeds on 1% agar. Chamber temperature ranged from 18 to 25°C, and observation lasted 30 days. A seed was considered germinated when its radicle was 2 mm long. [Jara-Peña et al. 2024]
Scarification preceded the light comparison
Preliminary trials yielded low germination in five taxa, including Austrocylindropuntia floccosa and Cumulopuntia ignescens. Before the main experiment, their seed coverings were lightly sanded with fine sandpaper. This treatment facilitated contact between seed and water and changed the starting conditions of both subsequent treatments. [Jara-Peña et al. 2024]
Assessment of light's role therefore concerns scarified seeds. A separate treatment comparison would require parallel trials with intact coverings and coverings prepared in the same way. In the comparison discussed, the key information remains the difference between two light exposures with a shared seed history. [Jara-Peña et al. 2024]
Two species, two responses
| Species and origin | 12 h of light per day | Continuous darkness |
|---|---|---|
| Austrocylindropuntia floccosa, Apurímac | 28.0% | 32.8% |
| Cumulopuntia ignescens, Arequipa | 36.0% | 0% |
Seeds of A. floccosa germinated in both treatments, which the authors classified as a photoblastically neutral response. Seeds of C. ignescens germinated only in light. The result shows variation even among Andean opuntioids studied by the same method. [Jara-Peña et al. 2024]
How to interpret the germination percentage
The germination percentage refers to the number of seeds in a particular sample. It depends on their viability, dormancy and incubation conditions. Light can signal that a seed is near the surface, and the response also depends on covering properties. In sowing practice, keeping information on batch origin, seed preparation, temperature and observation duration together is useful. [Jara-Peña et al. 2024]
Table 2 in the publication provides the basis for the percentages cited. The seed mass description gives differing information on the sizes of weighed samples, so mass values were left out of the comparison. This allows the conclusion about light to rest on the clearly presented part of the experiment. [Jara-Peña et al. 2024]
Prepared from scientific publications. Accepted names were checked in POWO on 9 October 2026.
Influencia de la luz en la germinación de semillas de 14 especies de cactáceas del Perú
Jara-Peña E., Quiroz A. J., Vela Arce M., Influencia de la luz en la germinación de semillas de 14 especies de cactáceas del Perú, Acta Botanica Mexicana, 2024, 131:e2273, doi: 10.21829/abm131.2024.2273
The experiment compares the germination of fourteen cacti in light and darkness. For Airampoa ayrampo (Tunilla soehrensii in the publication), it describes scarification and culture on an agar medium.
