Seed Germination Responses to Different Incubation Temperatures and Light Treatments in Four <i>Allium</i> species Native to Korea

Abstract

Allium L. is a perennial plant in the Amaryllidaceae family and includes 1,000 species. There are 24 indigenous Allium species in Korea, and they have a high value as genetic resources. However, there is a lack of research on indigenous Allium species and little research on recently classified or unknown Allium species, such as A. pseudojaponicum, A. dumebuchum, and A. ulleungense. Therefore, this study determined the effects of environmental control (temperature and light) on germination responses of four indigenous Allium seeds (A. longistylum, A. taquetii, A. pseudojaponicum, and A. thunbergii). Germination responses were evaluated by germination percentage (GP), days to 50% of germination of final germination rates (T50), mean germination time (MGT), germination uniformity (GU), and germination speed (GS). GP of A. longistylum and A. pseudojaponicum was more than 50% at 5°C, but A. taquetii and A. thunbergii did not germinate at 5°C. A. pseudojaponicum inhabits beaches in the southern region, and but A. longistylum inhabits near rivers and streams. However, A. taquetii and A. thunbergii mainly inhabit mountainous areas. Therefore, this difference is estimated to be in accordance with the environmental conditions of their habitat. At 5°C, the GP of A. longistylum was improved in dark conditions (90.0%) than in light conditions (68.3%); T50 and MGT were also shortened. The GP of A. taquetti increased at 15°C in the dark than light conditions, and T50 and MGT were shortened at 15°C and 20°C. Also, the GP and GU increased. At 5°C, the GP of A. pseudojaponicum was higher in the dark (83.3%) than in light conditions (70.0%); T50 and MGT were shortened at 15°C, and GS increased in the dark. At 15°C and 20°C of A. thunbergii, T50 and MGT were shortened, and GP increased in the dark. Therefore, in the relatively low-temperature group, dark conditions improved some germination responses than the light condition. Most of the four Allium seeds used in the experiment showed more than 90% GP at 15°C - 25°C, but other germination responses showed differences according to temperature and light. The T50, MGT, and GS of A. longistylum and A. thunbergii were the most improved at 20°C and 25°C, while A. taquetii and A. pseudojaponicum had the shortest T50 and MGT at 25°C, and the GS was the fastest. As a result, regardless of light, the proper temperature was 20°C – 25°C for A. longistylum, 25°C for A. taquetii, 25°C for A. pseudojaponicum, and 25°C in darkness and 20°C – 25°C in light for A. thunbergii.