BIOLOGY OF SEED GERMINATION IN SOME ONION SPECIES (ALLIUM L.)

Abstract

The possibility of seed reproduction is one of the factors of successful cultivation of resource plants in specific environmental conditions. The aim of the work was to study the germination behavior, quality and longevity of seeds in 15 onions (Allium L.) from the collection of the Central Siberian Botanical Garden SB RAS, Novosibirsk. The research was carried out in 1996–2019. Laboratory germination of seeds was determined according to generally accepted methods. Seeds were tested 3–7 months after harvesting at 17–23 °C in the light. The number of seeds in each Petri dish – 25–50; double replication. In the case of hindered germination, a two-month chilling at 4 °C was applied. In the future, laboratory germination was determined after 3, 5 and 7 years of room storage. We have established that onion seeds have three types of germinating. Seeds of type I – eight species, one variety from the subgenus Rhizirideum – usually lack dormancy. Germination is fast and simultaneous, and average germination percentages are 77.1–92.2 %. Seeds of type II – A. leucocephalum and A. microdictyon from the subgenus Rhizirideum, also A. caeruleum and A. flavum from the subgenus Allium – are characterized by stretched germination period due to the shallow dormancy, and their germination percentages vary from 32.6 % to 81.1 %. Seeds of type III – A. obliquum from the subgenus Rhizirideum and two species of the subgenus Melanocrommyum – do not germinate in room conditions, or germinate with low germination percentages, whereas chilling increases them up to 47.0–67.0 %. The hindered germination of these seeds is due to the deep organic dormancy. The economic longevity of onion seeds is 3–5 years, and the biological longevity varies at interspecific level within 5–8 years. Thus, the species that produce plump and good germinating seeds suitable for long-term storage – A. altaicum, A. bidentatum, A. flavum, A. microdictyon, A. nutans, A. ramosum, A. rubens, A. schoenoprasum, A. senescens, A. senescens var. glaucum, and A. strictum – have the highest reproductive potential in culture.