LONG TERM-STORAGE EFFECT ON VIABILITY AND FATTY ACIDS PROFILE OF Encyclia adenocarpa (Lex.) Schltr SEEDS.

Abstract

Mexico has 6 % of the Orchidaceae diversity, one of the most diverse botanic families; however, the habitat loss and the species overexploitation have diminished their populations. Seed banks could be a great option for storing ex situ Mexican orchids germplasm; in this kind of storing, seeds viability and biochemical profile should be evaluated periodically. Encyclia adenocarpa seeds collected in 2007 and 2014, preserved in UNAM FES Iztacala seed bank were aged for 0, 6, 12 and 18 d under 45 ºC and 45 % RH conditions. Seeds were germinated in Knudson C (KC) and Phytamax (PH) media (at 25 ± 1 ºC with photoperiod light 12 h/dark 12 h). Viability was analyzed using tetrazolium chloride assay, and the lipid acid profile was assessed. Scanning electron microscopy and optic microscopy were used for examining seed morphology. Six days aged seeds grown in Knudson C media showed 95 % of germination while wild seeds collected in 2007 did not germinated at all. Accelerated and natural ageing of seeds of E. adenocarpa reduced unsaturated fatty acid concentration modified their anatomy and embryonic structure. These damages caused loss of seed viability.