THE EFFECT OF COLD TREATMENT ON THE GERMINATION OF CARDIOCRINUM CORDATUM VAR. GLEHNII (LILIACEAE) SEEDS

The seeds of Cardiocrinum cordatum var. glehnii are characterized by a complex morphophysiological type of dormancy. There are three mechanisms of germination inhibition: two of them are localized in the embryo and one in the surrounding structures of the seed. To overcome these mechanisms, different temperature regimes for seed stratification are required.

It was revealed that the mechanism of inhibition of embryo postdevelopment is removed at higher temperatures of 18–20°C for 1.5 months for stored seeds or 2 months for fresh ones. Optimal rates of embryo development were observed at 9–10°C. At the end of postdevelopment, the embryos in different experimental variants could significantly differ in length. However, the degree of heterogeneity of the sample by embryo length did not affect the germination rate and the final percentage of germinated seeds.@The temperature regime during embryo postdevelopment did not affect the subsequent growth of the embryonic root and seed germination, as well as cold stratification at the beginning of the experiment did not stimulate embryo growth.

The development of embryo root was possible only after exposure to cold (0–2°C). It was demonstrated that the energy of seed germination and the germination rate significantly depend on the duration of cold stratification, regardless of the moment of exposure to cold. The longer the cold treatment was, the faster the seed germination. At the same time, not only cold stratification on water, but also dry storage of seeds at 0–2°C accelerated their germination.

Under natural conditions, seed germination of  C. cordatum var. glehnii occurs in 18–19 months after dissemination. In laboratory experiment, freshly harvested seeds of this species could be germinated in 7–8 months, taking into account that approximately 4 months of warm stratification are required for the further development of the embryo, and 3.5–4 months of cold stratification are required to remove the mechanism of germination inhibition.

Differences in the duration and period of exposure to cold, however, did not affect the final percentage of germinated seeds. In almost all variants, the final percentage of germination was high (from 86 to 100%).

The results of the experiment indicate that the process of seed germination of C. cordatum var. glehnii is realized in nature under the effect of different durations of temperature influences, which ensures the plasticity in the reproduction of this species in natural conditions.