RESUMEN
BACKGROUND AND AIMS: Orchid seeds are reputed to be short lived in dry, cold storage conditions, potentially limiting the use of conventional seed banks for long-term ex situ conservation. This work explores whether Cattleya seeds are long lived or not during conventional storage (predried to ~12 % relative humidity, then stored at -18 °C). METHODS: We explored the possible interaction of factors influencing seed lifespan in eight species of the genus Cattleya using physiological (germination and vigour), biochemical (gas chromatography), biophysical (differential scanning calorimetry) and morphometric methods. Seeds were desiccated to ~3 % moisture content and stored at -18 °C for more than a decade, and seed quality was measured via three in vitro germination techniques. Tetrazolium staining was also used to monitor seed viability during storage. The morphometric and germination data were subjected to ANOVA and cluster analysis, and seed lifespan was subjected to probit analysis. KEY RESULTS: Seeds of all Cattleya species were found to be desiccation tolerant, with predicted storage lifespans (P50y) of ~30 years for six species and much longer for two species. Cluster analysis showed that the three species with the longest-lived seeds had smaller (9-11 %) airspaces around the embryo. The post-storage germination method impacted the quality assessment; seeds equilibrated at room temperature for 24 h or in 10 % sucrose solution had improved germination, particularly for the seeds with the smallest embryos. Chromatography revealed that the seeds of all eight species were rich in linoleic acid, and differential scanning calorimetry identified a peak that might be auxiliary to selecting long-lived seeds. CONCLUSIONS: These findings show that not all orchids produce seeds that are short lived, and our trait analyses might help to strengthen prediction of seed longevity in diverse orchid species.
Asunto(s)
Germinación , Orchidaceae , Banco de Semillas , Semillas , Semillas/fisiología , Semillas/crecimiento & desarrollo , Orchidaceae/fisiología , Orchidaceae/crecimiento & desarrollo , Orchidaceae/anatomía & histología , Germinación/fisiología , Desecación , Rastreo Diferencial de CalorimetríaRESUMEN
Uma alternativa para conservação de espécies é um banco de sementes, onde é possível conservar e propagar estas plantas, porém para isto é necessário se ter uma noção da qualidade das sementes estocadas. Uma alternativa é utilizar testes de vigor, entre eles a deterioração controlada. O objetivo deste trabalho foi avaliar o efeito da deterioração controlada sobre sementes de orquídeas e determinar qual o tempo de exposição destas a este tipo de tratamento. Sementes de Cattleya schilleriana, C. tigrina, C. crispata e C. labiata foram submetidas à deterioração de zero a 48h a 43°C. Para sementes de C. crispata não foi encontrado um período adequado para o teste de deterioração controlada. Recomenda-se para as sementes de C. tigrina, C. labiata e C. schilleriana a utilização de 27 h a 43°C, todavia variáveis como o tempo e a temperatura ainda precisam ser melhores estabelecidos para este grupo de plantas. O teste de tetrazólio não foi eficiente para avaliar a qualidade das sementes após a deterioração controlada.
An alternative for conservation of this species is seed banking, based in that is possible to make conservation and propagations of the endangered species. But for this the seed quality must be monitored. Vigour tests can offer an option, and one of this is the controlled deterioration, which expose the seeds with high moisture to high temperatures during a determined period of time. The present work aimed to evaluate the controlled deterioration test over four orchid species in different times. Seeds of C. schilleriana, C. tigrina, C. crispata and C. labiata was submitted to deterioration from times ranging from zero to 48h at 43°C. For Cattleya crispata it was not found a effective time for the test. did not suffer any deterioration at any time. It is recommended for C. tigrina, C. labiata and C. schilleriana the use of 27 h at 43°C. However, time and temperature should be better studied for this group of plants. Tetrazolium test was not efficient to evaluate the seed quality after controlled deterioration.
Asunto(s)
Fenómenos Fisiológicos de las Plantas , Orchidaceae/fisiología , Semillas/fisiología , Banco de SemillasRESUMEN
Uma alternativa para conservação de espécies é um banco de sementes, onde é possível conservar e propagar estas plantas, porém para isto é necessário se ter uma noção da qualidade das sementes estocadas. Uma alternativa é utilizar testes de vigor, entre eles a deterioração controlada. O objetivo deste trabalho foi avaliar o efeito da deterioração controlada sobre sementes de orquídeas e determinar qual o tempo de exposição destas a este tipo de tratamento. Sementes de Cattleya schilleriana, C. tigrina, C. crispata e C. labiata foram submetidas à deterioração de zero a 48h a 43°C. Para sementes de C. crispata não foi encontrado um período adequado para o teste de deterioração controlada. Recomenda-se para as sementes de C. tigrina, C. labiata e C. schilleriana a utilização de 27 h a 43°C, todavia variáveis como o tempo e a temperatura ainda precisam ser melhores estabelecidos para este grupo de plantas. O teste de tetrazólio não foi eficiente para avaliar a qualidade das sementes após a deterioração controlada.(AU)
An alternative for conservation of this species is seed banking, based in that is possible to make conservation and propagations of the endangered species. But for this the seed quality must be monitored. Vigour tests can offer an option, and one of this is the controlled deterioration, which expose the seeds with high moisture to high temperatures during a determined period of time. The present work aimed to evaluate the controlled deterioration test over four orchid species in different times. Seeds of C. schilleriana, C. tigrina, C. crispata and C. labiata was submitted to deterioration from times ranging from zero to 48h at 43°C. For Cattleya crispata it was not found a effective time for the test. did not suffer any deterioration at any time. It is recommended for C. tigrina, C. labiata and C. schilleriana the use of 27 h at 43°C. However, time and temperature should be better studied for this group of plants. Tetrazolium test was not efficient to evaluate the seed quality after controlled deterioration.(AU)