Nine genotypes of melon (Cucumis melo L.) were selected for the investigation of regeneration. Most of the tested varieties showed regeneration ability on medium containing 0.5 mg l⁻¹ or 1 mg l⁻¹ BA, but following the appearance of shoot buds, only six varieties produced leafy shoots. The effect of combinations of BA with different auxins (IAA, NA, 2,4-D) and ABA in the culture medium on shoot regeneration was tested on cotyledon explants of 'Hógolyó' and 'Hale's Best'. To establish optimal conditions for the adventitious shoot induction six types of seedling-derived explants were prepared from seedlings of four different ages. The best results for shoot forming capacity were achieved with cotyledons followed by decapitated seedlings and hypocotyls derived from 4-day-old seedlings. Cotyledon segments of 'Hógolyó' and 'Hale's Best' were also cultivated on media with different concentrations of IAA and BA supplemented with 0.26 mg l⁻¹ ABA. The highest number of well-formed plantlets was counted for 'Hógolyó' on the medium supplemented with 0.9 mg l⁻¹ BA+ 0.6 mg l⁻¹ IAA+ 0.26 mg l⁻¹ ABA. This is the first report on the in vitro regeneration of 'Hógolyó' from decapitated seedling and hypocotyl explants and of 'JavÍtott Zentai', 'Muskotály', 'Hógolyó', 'Tétényi csereshéjú' and 'Magyar Kincs' from cotyledon explants.

Pumpkin, squash and zucchini are important vegetable crops in tropical and temperate regions. The development of genetic transformation methods offers the potential of introducing valuable traits into these crops. An efficientin vitroplant regeneration system is a critical point for genetic manipulation. The regeneration ability of threeCucurbitavarieties was tested on Murashige and Skoog medium supplemented with different growth regulators. Cotyledons of all the varieties were cultured to investigate the effect of 2,4-D (0, 1, 2, 3, 4 mg l−1) with or without KIN (0, 0.5, 5 mg l−1) and of BA (0, 1, 1.2 mg l−1) combined with IAA (0, 0.9, 1, 1.2 mg l−1), on the efficiency of shoot induction. Abscisic acid (0.26 mg l−1ABA) was also added to one medium. To find the most suitable combination for shoot induction, cotyledon segments of the three varieties were also cultivated on media with different concentrations of BA (0–1.2 mg l−1) and IAA (0–0.9 mg l−1). Shoot induction was achieved via organogenesis in the tested varieties. Leafy shoots were transferred to root induction media. Regenerated plantlets with roots were transferred to sterile soil. This is the first report onin vitroregeneration from cotyledon explants of the pumpkin cultivar Nagydobosi and the pattypan squash cultivar Óvári fehér.