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RESUMO

Knowing the physiology of seeds and the elements that influence their germination is fundamental aspects in seminiferous propagation; important techniques are used to obtain genetic variability and development of new cultivars of blueberry. The aim of this study is to evaluate the germination behavior, as well as viability levels, through germination tests and tetrazolium, of Vaccinium ashei Reade seed cultivars Briteblue and Climax. Seeds treated or not with 5 M potassium hydroxide (KOH) were submitted to the germination test, on substrates, filter paper (SP) or solid culture medium with half of the salt concentration (MS/2), at temperatures of 10˚C ± 2˚C or 25˚C ± 2˚C. The maximum germination percentage of blueberry seeds was 40%. Both temperatures and substrates caused seed germination in the tested cultivars, and pretreatment with 5 M KOH for 5 minutes inhibited germination. Yet, the tetrazolium test, based on coloration of tissue, allowed the establishment of different levels of viability.

In plant micropropagation, the establishment stage is difficult, due to the presence of microorganisms in tissues from field-grown matrices, especially for bamboo. This study aimed to establish an efficient asepsis protocol for Bambusa oldhamii explants from field plants, as well as to carry out the molecular identification of a possible endophytic bacterial isolate. The explants were exposed to 70 % alcohol, 1 % sodium hypochlorite (NaOCl), 0.1 % mercuric chloride (HgCl2), thiophanate-methyl (Cercobin®) and chlorhexidine digluconate (2 % Riohex®) in different combinations, and introduced into Murashige and Skoog culture medium (solid or liquid), supplemented or not with 4 mL L-1 of Plant Preservative Mixture (PPMTM), totaling seven treatments. The asepsis and immersion of the explants in the liquid culture medium containing 4 mL L-1 of PPMTM visually inhibited the bacterial and fungal growth, allowed the development of shoots with a mean length of 2.2 cm and posterior subcultures, being the best treatment used for the in vitro establishment of B. oldhamii. The molecular identification of an endophytic bacterium performed by 16S rDNA sequencing allowed to identify the bacterial isolate as Ralstonia sp., with 100 % of similarity, and the phylogenetic analysis grouped it with Ralstonia pickettii. In addition, the bacterial isolate showed to be sensitive to 4 mL L-1 of PPMTM by the minimum inhibitory concentration test.

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