INFLUENCE OF GENOTYPE AND CULTIVATION CONDITIONS ON VITROPLANTLETS EVOLUTION OF SOLANUM TUBEROSUM L. LOCAL VARIETIES

The local potato varieties from Gene Bank Suceava are maintained in a field collection and also by slow growth of in vitro culture. Slow growth method allows limited development of plantlets and the extension of time between two subcultures. This paper presents a part of the results about the influence of genotype, inhibitors from the media and conditions from the conservation room (temperature and light reduction), on potato plantlets preserved in vitro for different periods. Three grows inhibitors (daminozide, mannitol and sorbitol) and five local potato varieties of were included in the experiments. Several morphological features: number, length and branching of shoots, rooting, number of viable nodes, number and size microtubers and the viability rate of the shoots, were evaluated. Although there were differences in the growth type of potato varieties the main effect was the reduction of plantlets height, by shortening of internodes and leaves size. The leaf blade became very short (1,5 – 2 mm), many of them growing on the surface of some branches having a hypertrophic and translucent aspect. Could be noted a tendency to generate, also, well-defined microtubers bearing microbranches. The results on the response of plantlets developed on storage media recommended the medium C24, with 40 g / l sorbitol, as the best in terms of in vitro conservation of local potato varieties.