Physiological potential of Dyckia spp. bromeliad seeds under different temperatures

Bromeliads have been gaining ground in the economic scenario due mainly to their use as ornamental plants. Bromeliads of the genus Dyckia exhibit different morphologies, and therefore, have relevance in this market. However, some species are threatened due to the extraction of plants from their natural environments. Many of these species are endemic and native to Brazil and there are few studies on their seed physiology; hence, expansion of research into this topic is essential. An alternative for the preservation of such plants is the production of seedlings using seeds. To this end, the objective of this work was to evaluate the physiological potential of seeds of Dyckia brevifolia, Dyckia beateae, and Dyckia excelsa at different temperatures, and determine the number of days to carry out the tests. A completely randomized design was adopted, with three species of Dyckia, analyzed separately, and four temperatures (20, 25, 30, and 35 degrees C). The following were evaluated: first germination count, germination, germination speed index, length of seedling, and seedling dry weight. The data were analyzed using the Sisvar software for normality and homogeneity, and when the assumptions were met, they were subjected to analysis of variance using the F test (p < 0.05) and the means were compared using the Tukey test at 5% probability. Seeds of D. excelsa emit the radicle more quickly at 20 and 35 degrees C; however, temperatures of 25 and 30 degrees C provide better conditions for seedling growth and development. The greatest vigor of D. brevifolia seeds is observed at temperatures of 30 and 35 degrees C. Seeds of D. beateae emit the radicle more quickly at 20 degrees C, and the largest seedlings are observed at 35 degrees C. The first germination count of D. brevifolia, D. beateae, and D. excelsa should be evaluated on the third day after sowing. The germination evaluations for D. excelsa and D. beateae should be carried out on the ninth day after sowing, and those for D. brevifolia on the sixth day after sowing.