Effectiveness of methods to disinfect seeds of Laelia autumnalis for conservation in liquid nitrogen

Introduction : Laelia autumnalis is an endemic orchid species from Mexico which is threatened by its habitat loss. In order to preserve this species disinfestation and adequate drying methods are necessary developed of cryopreservation and in vitro culture technics. Method : For a good long-term storage optimization the direct immersion technic in liquid nitrogen was considered in the first experiment (E1), however, asymbiotic germination was affected by the fungi Alternaria sp.; because of that, a second experiment was carried out with two assays in order to evaluate the seed viability and asymbiotic germination based on 1% (w/v) of calcium hypochlorite (CaCl 2 O 2 ) and 15% (v/v) of commercial sodium hypochlorite (NaClO) as disinfection methods and using the air of laminar air-flow (A), silica gel (G) and vacuum pump (V) as drying methods before (E2) and after (E3) liquid nitrogen immersion (LN). Results : Viability was reduced in 49% and 37% by CaCl 2 O 2 and NaClO, respectively, while A and V drying methods were caused the highest viability loss (36 and 28%), respectively. The loss of viability in E3 was lower than E2 and it was observed a stimulation by NaClO in germination (100%). Conclusion : These seeds must be disinfected with NaClO and dried using the air of laminal air-flow after cryopreservation by direct immersion in order to avoid plant tissues damage.