Grmina??o de sementes e desenvolvimento in vitro de plantulas de Cattleya loddigesii Lindl. (Orchidaceae)

摘要

Th orchid family is among the world’s most endangered and Cattleya loddigesii Lindl. is in decline in the forests of the State of S?o Paulo. This study examined the influence of different culture media on germination and in vitro development of Cattleya loddigesii. Knudson C (KC), Vacin & Went (VW), Murashige and Skoog (MS), and MS media with half the concentration of nutrients (MS/2) were tested and compositions were supplemented with 2% sucrose and MS micronutrients. The percentage of viable seeds by tetrazolium test, the percentage of germinated seeds, the initial development and growth of plants after 180 and 360 days were the parameters evaluated. The viability test showed that approximately 68% of seeds were viable. Twenty days after the first signs of germination, the MS media yielded the highest germination percentage (77%). In the early development, after 180 days of in vitro culture the KC and VW media resulted in the largest number of seedlings with at least one leaf and root (93 and 91%, respectively), although many seedlings have died. At 540 days, the development analysis showed that plants in MS and MS/2 media presented higher fresh and dry masses of stem and highest number of leaves as well, producing more vigorous plants. Therefore, there was differential promotion of culture media at different stages of development C. loddigesii.