Cultivo In Vitro em auxílio à obtenção de tangerineiras triploides e propagação de porta-enxertos de citros

Abstract

In vitro cultivation techniques are important tools to support the production and propagation of citrus varieties, crowns and rootstocks. The objective of this work was to obtain triploid varieties of mandarins and to propagate rootstocks of agronomic interest by means of in vitro cultivation, using Wood Plant Medium - WPM. In order to obtain triploids, two experiments were carried out in the municipalities of Cruz das Almas and Mucugê, one based on fruits of open pollinations of the variety Ortanique, Clemenules, Montenegrina, Nova, Piemonte, Page, Dancy, Fremont, Ellendale, Fortune, Span Americana, Murcott, Kincy, Swatow and África do Sul, and another considering fruits of controlled crosses having as female parents ‘Nova’, ‘Fortune’ and ‘Ortanique’ and as male parents ‘Page’, ‘Montenegrina’, ‘Swatow’, ‘Fremont’ and ‘Kincy’. Fruits from both the natural pollination of controlled crossings were taken to the Laboratory for Tissue Culture of Embrapa Cassava and Fruticulture, and its seeds removed, these were inoculated into test tubes containing approximately 10 mL of WPM culture medium and brought into the growth room. When the plants reached about 60 days, leaf samples were taken for quantification of the DNA by means of the flow cytometry technique, according to the methodology described by Dolezel et al. (2007), with modifications. The highest frequency of triploids was obtained in Mucugê, in a total of 12 individuals: seven from controlled pollinations and five from open pollinations. In Cruz das Almas, only a triploid was obtained, from open pollination of the Kincy variety. The 'Ortanique' stands out for its greater potential for triploid production. Seeds of smaller size and undeveloped showed greater ability to generate triploids than normal seeds. Mucugê environment that has higher altitude and lower temperatures favored the formation of triploids. In relation to the propagation of rootstocks by in vitro culture, experiment was carried out with ten hybrids introduced or obtained by the Citrus Breeding Program of Embrapa Cassava and Fruticulture: ‘San Diego’, ‘Indio’ and ‘Riverside’ citrandarins, ‘Sunki Tropical’ mandarin, LRF x (LCR x TR) - 005, HTR - 051, HTR - 069, TSKC x (LCR x TR) - 059, LCR x TR - 001 and TSK x TRBK - Colômbia. Host nodal segments of the ten genotypes, approximately 1 cm long, were inoculated into glass vials containing 50 mL of the WPM medium. After 150 days of cultivation, the explants were subcultured in a new culture medium. The number of plants formed per explant was evaluated at 180 days after inoculation. The data were submitted to the F test of the analysis of variance and the means grouped by the Scott-Knott test at 5% probability. The WPM medium was suitable for the micropropagation of the genotypes studied, particularly 'Indio' citrandarin and TSKC x (LCR x TR) - 059 and TSK x TRBK - Colombia hybrids. Adjustments in the WPM medium are necessary to improve the micropropagation efficiency of 'Sunki Tropical' and LRF x (LCR x TR) - 005 and LCR x TR - 001 hybrids.