Growth regulators in the induction of calli in anthers of the Goldex hybrid yellow melon

The melon is of socio-economic importance, especially in the north-east of Brazil. Obtaining homozygous lines has been an obstacle in breeding programs. In vitro androgenesis is one alternative, requiring the development of protocols for anther culture. The aim of this work was to study the effect of auxins and cytokinins on callus induction in anthers of the Goldex hybrid yellow melon. Two experiments were conducted in a completely randomised design, with 25 replications. In the first experiment, in a 3 x 3 factorial scheme, the treatments comprised concentrations of 6-furfurylaminopurine - KIN (0.0, 3.0 and 6.0 mg L-1) and indolylacetic acid - IAA (0.0, 3.0 and 6.0 mg L-1), added to Murashige and Skoog (MS) medium. In the second experiment, six treatments were tested: MS with no growth regulator; MS + 0.20 mg L-1 6-benzylaminopurine (BAP); MS + 0.20 mg L-1 naphthaleneacetic acid (NAA); MS + 0.45 mg L-1 2,4-dichlorophenoxyacetic acid (2,4-D); MS + 0.20 mg L-1 BAP + 0.20 mg L-1 NAA; and MS + 0.20 mg L-1 BAP + 0.45 mg L-1 2,4-D. The following were evaluated 60 days after anther inoculation: induction percentage, oxidation intensity, colour, texture, and the area and fresh weight of the callus. The auxins (IAA, NAA and 2,4-D) and cytokinins (KIN and BAP) induce callogenesis in anthers, but only in combination, the most suitable being 0.20 mg L-1 BAP + 0.45 mg L-1 2,4-D. The calli have a beige colour, friable texture and medium oxidation, with a strong association between the fresh weight and the area