General combining ability and heterosis of sex expression traits in melon

Melon is an annual, cross-pollinated species belonging to the family of Cucurbitaceae. Melon plants are usually monoecious: male and female flowers develop on one plant, but most commercial varieties and hybrids are andromonoecious, and on their plants develop male and hermaphrodite flowers. On melon plants, male flowers appear first, and then develop flowers with female reproductive organs. In this experiment, eight melon genotypes (parents), of which four were monoecious (Sesame, ED-3, ED-4, Pobeditel), and four andromonoecious (Chinese muskmelon, Anannas, Honey dew, A2-3lb), and their 20 hybrids (monoecious) were used. The experiment was conducted in Smederevska Palanka, during two vegetative seasons. Seven characteristics related to sex expression were observed. The aim was to determine the parents with the best general combining abilities (GCA) and to determine the heterosis in their hybrids for all seven observed traits. Negative heterosis for the trait period from sowing to the emergence of the first perfect/pistillate flower was recorded in 16 of 20 genotypes. A reduction of the period between the appearance of male (positive heterosis) and perfect/pistillate flowers on plants (negative heterosis) was found in 12 hybrid combinations. It was found that in as many as 17 hybrid combinations, the fruits ripen earlier than their parents. All eight observed parental genotypes showed significant GCA values for most of the observed traits. The results showed that the Sesame was the best general combiner, and represented a potential source of the desired alleles required for the melon breeding programs