Seed analysis of Dichromanthus aurantiacus, terrestrial orchid from Toluca valley, México

Resumen

Objective: The objective of this work was to analyze the viability and germination of Dichromanthus aurantiacus seeds, a terrestrial orchid from Toluca valley, México.

Design/methodology/approach: The size and color were evaluated. Two methods determined the viability: 1) the tetrazolium test (imbibition for 24 hours in the water, 2 hours in calcium hypochlorite (CaCOCl₂), and drops of Tween-80). 2) the asymbiotic seed germination by in vitro culture (imbibition for 24 hours in the water, and the concentration of MS medium plus natural extracts).  

Results: The seeds of this specie showed approximately 0.2 mm long and 0.05 mm wide; they possess an embryo and a brownish testa. There were significant differences (P<0.05) between the treatments finding a positive effect with the tetrazolium test, achieving up to 91.4% viability. In the in vitro germination, the imbibition of the seeds favored contamination. The concentration of MS and the addition of natural extract presented significant differences (P<0.05), the 50% MS plus 10% of coconut water showed up to 92.8% of germination at 60 days.

Study limitations/implications: The results are preliminary of a long-term experiment.

Findings / Conclusions: The seeds of Dichromanthus aurantiacus showed brown testa and an oval embryo with dimensions of 0.2 mm long and 0.05 mm wide. The tetrazolium test’s viability showed 91.4% viability when they were soaked in sodium hypochlorite solution (CaCOCl2) for two hours, 24 hours soaking in tetrazolium solution (1%) plus two drops of Tween-80. The asymbiotic in vitro culture showed up to 92.8% germination in 60 days using MS medium at 50% enriched with 10% coconut water