Germinação in vitro de sementes e indução de organogênese em meloeiro

Abstract

The melon (Cucumis melo L.) is a plant with great economic interest, cultivated in tropical and subtropical regions in several countries, including Brazil. Due to the climate, the Northeast is the most melon producing region in Brazil. Organogenesis is a morphogenetic pathway widely used as a technique in plant tissue culture because it provides advantages such as high clone multiplication rate, large-scale plantlets production and reproduction of elite plants developed through genetic improvement programs. Aiming the complete regeneration of melon plants, the present work has the objective of developing a protocol for in vitro germination protocol of Cantaloupe type melon seeds and the determination of the ideal concentration of growth regulators for induction of organogenesis in cotyledonary explants of the melon types Pele de Sapo and Cantaloupe. For the in vitro germination, the Cantaloupe seeds were submitted to ten pre-germination treatments such as seed soaking in autoclaved distilled water by different time intervals and the removal or not of the tegument. For the induction of organogenesis, 12-day old cotyledon segments of the two types of melon were used in MS culture medium containing different concentrations of 6-benzylaminopurine (BAP). The data were submitted to an analysis of variance (ANOVA) and the means compared by the Scott-Knott test (p <0.05). The best pre-germination treatment was obtained with the tegument removal, resulting in 100% germination, three days after in vitro inoculation of the seeds of melon type Cantaloupe. These results indicate that the tegument retards the in vitro germination of the seeds due to poor permeability to water. In the induction of organogenesis occurred the formation of calluses, buds and adventitious shoots in the Cantaloupe type, and only calluses and adventitious buds in Pele de Sapo. The best concentration of growth regulator for the development of calluses and adventitious buds was 3.0 mg L-1 of BAP with fresh weight average of 3.7 g of calli per explant and 88% of explants forming buds and adventitious shoots, in the type Cantaloupe and for the Pele de Sapo just about callus formation with 1.8 g of fresh mass average. The type Pele de Sapo did not show conclusive results regarding the induction of adventitious buds. The induction of organogenesis in melon is dependent of the concentration of the growth regulator BAP and, mainly, the genotype.