Effects of duration and conditions of storage on germination of seeds of Pedicularis sceptrum-carolinum (Orobanchaceae)

Abstract

Choosing optimum conditions for plants of the Pedicularis genus to productively germinate and undergo the initial stages of development is currently a relevant problem in the search of solutions to successfully grow these taxa. For the experiments, seeds of Pedicularis sceptrum-carolinum L. (Lamiales, Orobanchaceae) were collected in the first decade of September in the vicinity of Chashnitskoe Lake. The study of specifics of germination of seeds and the initial stages of the development of P. sceptrum-carolinum was carried out in controlled laboratory conditions in a climate chamber with illumination (1,200–1,500 lux, photoperiod of 9/15, temperature of 23–25 °С). After a month-long storage of seeds in their fruit capsules in the laboratory conditions, the greatest germination (83.3–93.3%) was achieved after their subsequent dry maintenance (taken out of the fruits) in a refrigerator at the temperature of +2…+3 ºС for 3 or 6 months. Lower values of final germination were obtained after maintaining dry seeds at the temperature of –24…–28 ºС for 3 months. Increasing periods of such storage up to six months led to decrease in the final germination and energy of germination. After-ripening lasting different periods provided lower values of the two most important parameters – final germination and energy of germination, even in cases of quite long periods of dry storage in the laboratory. The initial stages of the development of plants from seeds of P. sceptrum-carolinum, which had undergone 3-month stratification in a refrigerator, were studied during the period of 2.0 (2.5) months in different conditions: Petri dishes on moistened filter paper, and in glass vessels with settled tap water, in soil in a plastic container (pure groups of sowed seeds) and also in soil sown together with seeds of Avena sativa L., with seeds put singly into a plastic block of 9 cassettes. The study revealed morphological differences in plants that had developed over the two-months growth, in each variant of the experiment. We recorded fragmentary development of haustorial hairs on the lateral roots of the plants in the pure sown group and also the haustorium in the group sown together with common oat. We achieved no further development and the plants died. The plants grew for a longer period (2.5 months) in the pure sown groups, which then died as well. The study we performed may be a basis for preparing successful introduction and cultivation of P. sceptrum-carolinum, which would be an important source of preservation of a species that raises concerns on account of the rapid decreases in its populations, narrowing of its range and rare occurrence.

Keywords

• rare species; hemiparasites; generative reproduction; germination; avena sativa; morphological differences.