Effects of different disinfectants and culture substrates on aseptic germination and aseptic seedling establishment of Cajanus cajan (L.) Millsp

To establish an efficient and stable aseptic germination system for pigeonpea seeds ( Cajanus cajan (L.) Millsp. ), the present study investigated the effects of disinfectant type, disinfection time, and culture substrates on the pigeonpea seed germination rate, germination dynamics, aseptic seedling rate, aseptic seedling growth dynamics, and contamination. Disinfectant, disinfection time, and culture substrates all influenced the aseptic germination and establishment of aseptic seedlings of pigeonpea seeds significantly ( P < 0.05). Disinfection with 5% sodium hypochlorite (NaClO) for 5 min was the ideal treatment, with the seed germination rate and aseptic seedling rate being significantly higher than those under 0.1% mercuric chloride (HgCl₂) and the control group. The germination rates on Murashige and Skoog (MS) medium and sterile filter paper were 80.00% and 81.11%, respectively, and the aseptic seedling rates were 55.56% and 81.11%, respectively. Seed germination and aseptic seedling rates of the 5% NaClO group decreased slightly with an increase in disinfection time, whereas the 0.1% HgCl₂ group exhibited a significant declining trend due to higher toxicity. Under the same disinfection conditions, culture on sterile filter paper was superior to that on MS medium in terms of germination speed, final germination number, aseptic seedling quantity, and contamination control. The contamination level was in the order of sterile water control group > 0.1% HgCl₂ group > 5% NaClO group. According to the results, disinfection with 5% NaClO for 5 min combined with culture on sterile filter paper was the ideal disinfection and culture strategy for pigeonpea seeds. The system above featured stable disinfection efficacy, low phytotoxicity, high germination and aseptic seedling rates, and it could control contamination effectively. The results could provide theoretical and technical support for pigeonpea tissue culture, in vitro regeneration, genetic transformation, and industrial seedling production.