Obtaining Triploid Hybrids by Means of Open Pollinations and Controlled Crosses Involving Diploids Parental

Abstract

The creation of triploid hybrids is an important genetic improvement strategy for the development of new commercial citrus scion varieties. The objective of this work was to quantify the frequency of triploids obtained from natural and controlled crosses of different mandarin varieties under varying environmental conditions in the state of Bahia. The experiments were conducted in the municipalities of Cruz das Almas (Recôncavo Baiano region) and Mucugê (Chapada Diamantina region). The first experiment was based on fruits from open pollinations of the varieties ‘Page’, ‘Ortanique’, ‘Ellendale’, ‘Clemenules’, ‘Swatow’, ‘Piemonte’, ‘Fortune’, ‘South Africa’, ‘Montenegrina’, ‘Kincy’, ‘Span Americana’, ‘Fremont, ‘Nova’, ‘Dancy’ and ‘Murcott’, and the second involved fruits from controlled crosses of female parents ‘Nova’, ‘Fortune’ and ‘Ortanique’ and male parents ‘Page’, ‘Montenegrina’, ‘Swatow’, ‘Fremont’ and ‘Kincy’. The seeds selected were inoculated in test tubes containing approximately 10 mL of Woody Plant Medium (WPM). When the plants reached circa 60 days of age, leaf samples were removed for quantification of the DNA by the flow cytometry technique. In Mucugê, three triploids were identified from open pollinations, ‘Clemenules’ (1) and ‘Ortanique’ (2), while in Cruz das Almas, no triploids were obtained. In the controlled crosses, triploids were only obtained in Mucugê: ‘Ortanique’ × ‘Montenegrina’ (4), ‘Ortanique’ × ‘Kincy’ (1) and ‘Ortanique’ × ‘Swatow’ (2). Based on the data, it is suggested that the environmental conditions of Mucugê favored the formation of triploids.