EVALUATION OF SEED QUALITY IN СOSTUS DUBIUS (АFZEL.) K. SCHUM

Seed exchange between Botanical gardens is often the only opportunity to replenish the species diversity in collections with rare or exotic plants. The need to select and provide high-quality seed material in Index Seminum, as well as to determine the storage time of seeds is an urgent task. The objects of the study were seeds collected from adult Costus dubius plants growing in the greenhouse at the Botanical Garden of Samara University. The paper presents information for 8 years about the morphology, humidity, weight of 1 000 seeds, their completeness and germination. The length of the seeds varied from 1,844 to 3,380 mm, the average length of the seeds was 2,437 mm. The mass of 1000 seeds varied from 3,091 g to 4,005 g, the average mass of 1 000 seeds was 3,463 g. After air-dry storage, the moisture content of seeds was in the range of 5.99–8.52 %. An express assessment of seed quality was carried out using digital microfocus radiography. The seed maturity ranged from 98.54 to 100 %. No signs of colonization or damage by pests were found on seeds. The first seedlings of C. dubius from 2020 and 2021 collections appeared on the 11th day from the beginning of the experiment. Laboratory germination of seeds varied from 22 % in 2018 to 68 % in 2021. Seeds stored for more than 5 years at a temperature of 24–25 о C completely lost their germination. Based on the data we have obtained; we recommend that only the seeds of the current harvest year should be included in the Index Seminum.