Seed Size as Key Factor in Germination and Seedling Development of Copaifera langsdorffii(Fabaceae)

Seed size is a plastic trait of the plants that directly affect seed germination and seedling recruitment. This study aimed to investigate the relationship between seed size, seed germinability and seedling performance of Copaifera langsdorffii by testing four hypotheses: 1) larger seeds have higher germination percentage;2) smaller seeds require less time to germinate and for initial development of the seedlings;3) larger seeds produce more vigorous seedlings and 4) seed size negatively affects seedling root/shoot ratio. In 2011, we selected 30 individuals of C. langsdorffii from which 300 seeds were randomly collected in the plant canopy. All these seeds were weighted and placed in germination tray using vermiculite as substrate. Seed germinability and initial development of seedlings were monitored daily until cotyledons fell. Small seeds have higher germination percentage and germinate faster when compared to large seeds. Nonetheless, seedlings originated from larger seeds have longer development times, resulting in more vigorous seedlings. In addition, seedlings originating from small seeds allocate proportionally greater amount of resources to roots when compared to larger seeds. The fact that small seeds have higher germination percentage and faster germination favors the colonization of transient habitats. However, larger seeds produce more vigorous seedlings, favoring the seedling establishment in more stable habitats. Thus, we argue that high variability in seed size of C. langsdorffii favors its widespread geographic distribution.

Cell Viability of Byrsonima intermedia A Juss Calli

Byrsonima intermedia A Juss. is a species with pharmacological properties from the Brazilian Cerrado that shows difficulties related to sexual propagation. Research on cell viability may provide useful information for the selection of cells with embryogenic potential during the callus culture, Within this context, our research is aimed at establishing the cell viability of calli from Byrsonima intermedia leaf segments. The calli went through three subculture phases, of 60 days each, in MS medium with 0.09 M sucrose, 0.6% agar, pH 5.8 and 4.52 laM 2,4-D. The calli were stored in dark conditions and samples were collected every 10 days from each subculture for viability tests with fluorescein 3,6-diacetate （FDA） and 2,3,5-triphenyltetrazolium chloride （TTC）. The staining methods allowed quantifying cell viability in each subculture. The best results from the FDA tests were obtained at 21, 25 and 29 days for the first, second and third subcultures respectively, with 53,86%, 61.88% and 53.73% viable cells. Regarding the TTC test, the largest absorbance values were obtained at 21, 27 and 28 days for the first, second and third subcultures respectively. Fluorescence and spectrophotometry analyses were efficient for determination of cell viability during callus cultivation period.