Degree of moisture in seeds for the cryopreservation of orchids native to Brazil

Edilene Aparecida Preti Ferrari,Franciele Da Silva Vero,Ronan Carlos Colombo,Carmen Silvia Vieira Janeiro Neves,Ricardo Tadeu De Faria

doi:10.1590/0103-8478cr20180498

Abstract

ABSTRACT: The objective of this study was to determine the ideal moisture degree for the cryopreservation of Cattleya labiata Lindl. and Miltonia regnellii Rchb.f. orchid seeds. Orchid seeds were standardized in relation to the desired moisture degrees (4, 6, 8, 10, 12, and 15%) and were subjected to rapid freezing in liquid nitrogen (-196 °C) for 24 h; then, the seeds were defrosted and analyzed. For both orchid species, the seeds that were immersed in liquid nitrogen with 4% moisture content had the highest viability percentage, averaging 95% and 68% of viable seeds for C. labiata and M. regnellii, respectively. The seeds with 12% and 15% moisture content had no viable seeds. For the fresh mass of seedlings, there was no significant difference between moisture content treatments for either species.

Highlights

In order to achieve success in the ex situ conservation of orchid germplasms, it is necessary to know the structural and physiological changes that can happen in the seeds when subjected to a reduction in the degree of moisture and stored at low temperatures
Among the degrees of moisture studied in the seeds of C. labiata, it was reported that the seeds immersed in liquid nitrogen with 4% moisture content showed the highest percentage of viability, reaching 95%
As the seed moisture degree increased, a reduction in viability was observed by the tetrazolium test; the 10% moisture degree was responsible for a viability of 62%

Summary

Introduction

In order to achieve success in the ex situ conservation of orchid germplasms, it is necessary to know the structural and physiological changes that can happen in the seeds when subjected to a reduction in the degree of moisture and stored at low temperatures. Cryopreservation is a technique that can be used to store plant material without a time limit, since it reduces metabolism to levels so low that all biochemical processes are practically paralyzed (KARTHA, 1985). The techniques used in the cryopreservation of plants are controlling the rate of refrigeration, vitrification, encapsulation, dehydration, and dormant buds’ preservation (REED, 2008). These techniques can promote the simultaneous storage of different parts of the studied plant. In orchid seeds, Approved 04.08.20 Returned CR-2018-0498.R4 by the author 07.21.2C0 iência

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