Abstract:
Objective Medium formulation and culture conditions were optimized for in vitro pollen germination of Oncidium spp.
Methods On a liquid culture medium, in vitro germination rates of the pollens collected from the flowers of various Oncidium germplasms on the day of full bloom were determined. Based on the effects of sucrose, H3BO3, Ca(NO3)·4H2O, MgSO4·7H2O, and KNO3 on the germination rate, an orthogonal experiment was applied to optimize the medium formulation and culture conditions. Subsequently, on the optimized medium under selected conditions, in vitro pollen germination rates of 68 collected Oncidium germplasms were determined.
Results The degrees of importance of the medium ingredients to the pollen germination were found to be H3BO3>Ca(NO3)·4H2O>sucrose>MgSO4·7H2O>KNO3. The optimized formulation consisted of 100 g·L−1 of sucrose, 10 mg·L−1 of H3BO3, 50 mg·L−1 of Ca(NO3)·4H2O, 20 mg·L−1 of MgSO4·7H2O, and 30 mg·L−1 of KNO3. The pollen culture was conducted at 25 ℃ for 48h in darkness to deliver a generally low germination rate of 0.74% to 49.65% on 60.29% of the Oncidium germplasms.
Conclusion The liquid medium and culture conditions for an in vitro pollen germination of Oncidium were optimized. The germination rates differed significantly among the species.