Two species from the same area
Masini, Rovere and Pirk collected seeds of Maihuenia patagonica and Maihueniopsis hickenii in Auca Mahuida, Argentina. They described the second species as M. darwinii var. hickenii. After 60 days of storage at 5°C, they compared a control, moist cold stratification and two scarification methods. Each treatment had ten replicates of thirty seeds. [Masini et al. 2014] [2-WWW]
Stratification lasted 40 days at 5°C. Mechanical treatments included abrasion and cutting with a scalpel. A 20/10°C cycle with a twelve-hour day was then maintained. In M. hickenii, a scalpel was used to remove a fragment of the outer covering of funicular origin, preserving the seed coat proper. This distinction reflects the structure of opuntioid seeds. [Masini et al. 2014]
The result depended on the species
Mean final germination across treatments was about 8–27% in Maihuenia patagonica and 17–26% in Maihueniopsis hickenii. Observation lasted about two months. In the first species, the scalpel treatment exceeded the control. In the second, no treatment significantly increased the final percentage relative to the control, although stratification accelerated the onset of germination. [Masini et al. 2014]
The viability of the remaining material was assessed after the experiment. The authors considered non-deep physiological dormancy, the influence of coverings and the temperature used in the experiment. The absence of a radicle over a short period therefore does not establish whether a seed has died or remains viable in a dormant state. [Masini et al. 2014]
Pterocactus tuberosus needs hydration
A separate study examined Pterocactus tuberosus seeds from La Pampa, stored dry for 2–10 months. Each treatment had five replicates of ten seeds. Within 30 days at 25°C, mean germination was 84% in light and 58% in darkness. Light increased the proportion germinating, but some could also develop without it. [Kin et al. 2015]
Reducing water potential with polyethylene glycol solution strongly limited germination. At −0.7 and −1.0 MPa, most seeds remained ungerminated. After transfer to distilled water, some began growing, indicating retained viability despite the earlier adverse conditions. [Kin et al. 2015]
Sowing temperature and subsequent growth
P. tuberosus germinated best in the treatments covering 20–35°C and in 25/15 and 30/20°C cycles. At 15°C, the proportion was low, and at 40°C seeds did not germinate during the experiment. The result describes a particular seed sample on moist substrate and indicates a range for planning further experiments with one's own material. [Kin et al. 2015]
After germination, a seedling becomes a plant with its own water balance. In a greenhouse study of P. tuberosus, reduced watering decreased growth and mass even when plants remained viable. Survival under water shortage and effective growth therefore require separate descriptions. Detailed conditions are given in the species profile. [Kin et al. 2015]
Prepared from the publications read. Metrics, experimental conditions and tabular data were checked against the source material.
Requerimientos pregerminativos de Maihuenia patagonica y Maihueniopsis darwinii, cactáceas endémicas de Patagonia
Masini A. C. A., Rovere A. E., Pirk G. I., Requerimientos pregerminativos de Maihuenia patagonica y Maihueniopsis darwinii, cactáceas endémicas de Patagonia, Gayana Botanica, 2014, 71(2):188-198, doi: 10.4067/s0717-66432014000200002
The experiment compares germination in Maihuenia patagonica and Maihueniopsis hickenii, called M. darwinii var. hickenii in the paper. It includes cold stratification, two scarification treatments, seed measurements and a viability test. It discusses possible physiological dormancy and the effects of seed coverings.
Seed germination and seedling growth of the geophytic Pterocactus tuberosus (Cactaceae)
Kin A. G., Mazzola M. B., Cenizo V. J., Seed germination and seedling growth of the geophytic Pterocactus tuberosus (Cactaceae), Journal of the Torrey Botanical Society, 2015, 142(4):283-291, doi: 10.3159/torrey-d-14-00056.1
Experiments on the effects of water potential, temperature and light on germination in Pterocactus tuberosus. A separate section compares the growth of young seedlings at three watering frequencies. The results describe the difference between germination conditions and drought tolerance after storage organs have formed.
Plants of the World Online — Royal Botanic Gardens, Kew
Accepted names, synonyms and distribution. A citation beside a taxon leads to its record.
Accessed 2026-10-08.
