Conservação de políneas de espécies ameaçadas de Cattleya sp. em diferentes condições de armazenamento

Abstract

Cattleya are orchids commonly used for ornamentation. The intense collecting pressure of native plants and environment degradation has increased the number of plants under extinction. The use of germplasm banks is crescent to preserve and propagate these plants. The objective of this work was to study the storage conditions for conservation of políneas, evaluating the quality of the pollineas since their collection, and the production of seeds based on the stored and fresh pollineas. Cattleya kautskyana and C. intermedia were used as model species. Pollineas were conditioned at different Relative Humidity (RH) obtained by silica gel (4.5% RH) and lithium chloride solutions (g/100 mL): 30% RH (52 g), 50% RH (36.4 g) e 80% RH (17.1 g) and stored at 5, -18 and -196 ºC. After equilibration pollineas germination was scored periodically and after one year the políneas were used to pollinate fresh flowers. Seed capsules were collected and evaluated by germination and tetrazolium test. Data were expressed in percentage in average values and standard error and submitted to analysis of variation and compared by the Scott-Knot test. The storage effect varied between pollineas of both species being able to produce fruits and seeds. Pollineas of Cattleya intermedia were more affected by storage, because they pollineas were not able to set fruits in any treatments stored at 5 ºC or a few at -18 or -196 ºC, and even the seeds produced by Cattleya intermedia showed poor vigour. Cattleya kautskyana pollineas were more tolerant to most of conditions of storage, with a higher capsule setting and seed filling with high viability and germination, including some treatments stored at 5 ºC. There were differences between lipid composition, which affect the storability and viability of the pollineas. Cattleya intermedia showed a high lipid content and with high amounts of saturated fatty acids implying in poor storability. Crioconservation at -196 ºC was better for both species but the RH for equilibrium might be different.