Germination of soybean seeds after low-temperature storage and its dependence on weather and climate conditions in the places of reproduction of accessions

Abstract

Background. Soybean (Glycine max (L.) Merr.) is a microbiotic whose seeds quickly lose germination in uncontrolled conditions at room temperatures. This determines the need to preserve accessions in special conditions. Low temperature storage (LTS) allows to maintain high seed germination ability, but not for all accessions. Therefore, it is relevant to assess the results of LTS at the VIR Genebank and to make an attempt to determine the best geographical conditions for growing plants and harvesting seeds that will be subjected to LTS. Materials and methods. The work was carried out on 312 soybean accessions from the VIR collection, originating from almost the entire area of soybean cultivation. The accessions used in the research were reproduced at three VIR experiment stations (ES), namely Adler ES, Kuban ES (Krasnodar Territory) and the Far East ES (Primorsky Territory). The seeds were harvested in 1999 to 2017 and stored in sealed foil laminated bags at –10°C from 2002 to 2021. The accessions were removed from LTS and germination assessed in 2022. Results. At the beginning of LTS, seed germination (Gi) ranged from 12 to 100% (averaging 79.1%), while that after LTS (Gr) ranged from 1 to 97% (57.8% on average). The retention of germination ability was expressed as the germination index (GI = Gr / Gi), which ranged from 0.02 to 1.73 (an average of 0.72). All the indicators of germination in the range of up to 20 years of LTS were not associated with the duration of LTS and with the number of years before LTS (0.5-4 years in our research). The climatic conditions characteristic of the place of reproduction had a significant impact on Gi and Gr, but not on GI. The average Gi of seeds obtained at the Adler ES and Kuban ES did not differ significantly (77.4% and 75.7%), while that of seeds harvested at the Far East ES was significantly higher (84.0%). Gr of the accessions from the Far East ES (64.3%) was also greater than that of accessions from the Kuban ES (52.2%) and Adler ES (57.2%). The excessively high sum of temperatures above 10°C (recorded in some years at all stations) reduced Gi, Gr but had little effect on GI. The highest values of Gi, Gr, and GI were demonstrated by the accessions maturing in 101-120 days. Additionally drying of the most late-ripening accessions (later than 140 days) in sheaves under an awning yielded seeds with high germination ability and good LTS tolerance. Conclusion. The seeds from different places of reproduction of accessions differed in germination before and after LTS, and, on an average, the highest values were demonstrated by the seeds harvested at the Far East ES, where the temperature regime is closer to the optimal one for soybeans. The seed germination index showed relative independence from the conditions of reproduction of accessions, including the climate and weather conditions, as well as the initial germination ability and LTS duration.