Biotechnological researches on micropropagation of Diyarbakır watermelon genotypes (Citrullus lanatus cv. `Beyazkış?, `Karakış? and `Sürme?)

The objective of this study was to develope a micropropagation protocol for three diploid Diyarbakır watermelon types (Citrullus lanatus cv. `Beyazkış?, `Karakış? and `Sürme?), because these types are prone to extinction due to pollinasation with hybrid seeds. It was also aimed to obtain tetraploid lines from the cultured diploid lines.The seeds, after removing seed coat, were surface disinfected by shaking on a shaker for 10-15 min in 4% of NaOCl followed by three times rinses with sterile water and cultured on MS medium (Murashige and Skoog, 1962) to germinate. Shoot tips were obtained from the diploid Diyarbakır watermelon types by culturing in vitro grown seedlings (5-day-old) on shoot regeneration medium for 3 weeks. Optimum concentration of BA for adventitious shoot regeneration among the cytokinins (BA and Kin) tested was determined as 1.0 mgl-1 BA for `Karakış? and `Beyazkış?, and 0.5 mgl-1 BA for `Sürme?. Axenic regenerants of `Sürme?, which is commonly grown in the region, was also tested with five diffferent amino acids (leusine, methionine, triptophan, valine, alanine) and three different polyamines (spermine, spermidine, putrescine) in order to increase shoot proliferation. Shoot proliferation was the best in MS medium containing 100 ?M methionine together with 50 ?M spermine.For the rooting of in vitro regenerated shoots, 1.0 mgl-1 IBA gave the best results among the cytokinins (IBA, IAA and NAA) tested for the three watermelon types. 76%, 91% and 95% of rooting were achieved when the medium was supplemented with 1.0 mgl-1 IBA for the three genotypes, `Beyazkış?, `Karakış? and `Sürme?, respectively. The acclimatised plantlets were readily transplanted to the field. Yield and main soluble sugar of experimental types were determined, but there was no statistically siginificance for the seeded and transplanted watermelon.In order to obtain polyploidy, both in vivo and in vitro methods were studied. Ploidy levels were determined by stomatal chloroplasts number, and the total DNA amount were recorded with spectrophmetric determination to screen a large number of plants for ploidy levels. As a result of this study it reported that in vitro methods are more suitable than in vivo methods to obtain tetraploid lines for the watermelon types studied. In addition to this, it was also reported that the doubling with 0.03% colchicine was 16.2%, 23.5% and 27.0% for `Beyazkış?, `Karakış? and `Sürme?, respectively.