Tetrazolium test for seed viability and germinability of Melocactus ernestii Vaupel subsp. ernestii and Melocactus zehntneri (Briton & Rose) Luetzelb. (Cactaceae)

Despite its ornamental value, some Melocactus species (Cactaceae) are threatened by several factors and only sexual propagation is possible. Thus, artificial seed banks are an appropriate method for their ex situ conservation. Suitable methods to germinate and to monitor viability are necessary for the seeds of these species. This work explored the use of tetrazolium test for monitoring seed viability of two Melocactus species. There was a correlation between the percentage of stained embryos, considering different cover area or tone stain, and the germination percentage. Unviable embryos did not stain. The embryos curved shape can explain the partial stain on the most of cases.

Analysis of single and binary phases in cerium doped sodium bismuth titanate -Na0.5Bi0.5TiO3 materials

The pure and cerium doped sodium bismuth titanate inorganic powders were synthesized by solid state reaction method. The presence of rhombohedral phase was observed in cerium doped NBT compounds. At 1200 ºC, the 5% of cerium doped NBT compound forms single perovskite phase. The samples of x = 0.10 and 0.15 were heat treated to 1350 ºC, the binary phases with cerium and bismuth oxides were observed. The X-ray diffraction, fourier transform infrared spectroscopy, reflectance spectra, differential thermal analysis and thermo gravimetric analysis were used to analyze the various properties of samples. Moreover, the effects of cerium doping and calcining temperature on NBT samples were investigated. In this work we present our recent results on the synthesis and characterization of Ce doped sodium bismuth titanate materials.