A PRELIMINARY-STUDY ON THE EFFECTS OF NITROGEN SUPPLY ON THE GROWTH-INVITRO OF 9 POTATO GENOTYPES (SOLANUM SPP)

Cultures of nine potato genotypes (seven Solanum tuberosum, one S. spa rsipilum and one S. oplocense genotypes) were examined for their respo nse to growing on medium containing either 60 mol m-3, 40 mol m-3 or 2 0 mol m-3 nitrogen. Genotypes differed in their response to nitrogen. Reducing the nitrogen regime tended to produce taller plants with long er internodes, shoots had larger leaves but contained less chlorophyll . No change in fresh weight or number of nodes was observed. Genotype x nitrogen interactions were significant for chlorophyll content, shoo t length and internode length. Results suggest that the changes observ ed were as a result of changes in the total nitrogen level rather than changes in the ammonium: nitrate ratio. This study suggests that for certain potato genotypes, nitrogen levels in MS medium are too high fo r producing desirable microplants in terms of leaf area and shoot leng th.