Light supplement by dark break shortens the growth period from bulblet to virus-free seed garlic

•The production period of virus-free seed garlic was shortened by the artificial control of light supplementation and substrate cultivation.•Resultant commercial garlic had improved virus-free effects and quality.•Breeding efficiency nearly five times better than conventionally farmed garlic.•Light supplement with dark break greatly increased bulb formation. The garlic (Allium sativum L.) industry is faced with severe problems such as virus accumulation and low reproduction coefficients due to long-term asexual propagation. In vitro propagation may be an effective method to solve such problems. In the present study, a complete virus-free and rapid propagation technology system from explants to bulblets have been established based on a tissue culture method using the inflorescence of the introduced and domesticated Xinjiang purple peel garlic “Jiangjin No.1″ as explants. The inflorescences were divided into three groups based on the length ratio of the flower stem to the pseudostem to optimize the harvest time of explants. The result indicated that the inflorescences harvested during the stage when the ratio of flower stem length to pseudostem length was 08–0.9 had the best induction efficiency of bulblets. The obtained virus-free seed garlic and commercial garlic were tested for physio-biochemical and viral indices. Subsequently, the effects of different photoperiod treatments and culture media on the growth of plants originating from the bulblets were assessed. Our results indicated that the virus-free seed garlic and commercial garlic exhibited good virus-free effects and their quality was improved to a large extent. Concomitantly, the breeding efficiency was nearly five times higher than that of traditional breeding methods, resulting in greatly reduced production cost. The formation of underground bulbs was significantly affected by photoperiod treatment, while substrates had a slight influence. The underground bulb formation rate could reach 96% when the bulblets were cultivated on an inorganic substrate under the light source to break the darkness at night. The whole process from bulblets to virus-free seed garlic was completed in a relatively short period (four months) by providing the required nutrients regularly and replenishing artificial light. Compared with conventional field planting, the production period of virus-free seed garlic was shortened by approximately a year. Overall, our study can give important insights into the process optimizati