Adequação da condição de crescimento para a conservação in vitro de germoplasm de citros

Abstract

The in vitro conservation is an efficient alternative and a complementary strategy to traditional conservation of citrus. This study aimed to establish slow growth conditions for in vitro conservation of citrus genotypes. The factors considered were the basic medium WPM concentration, sucrose concentration, incubation condition and univariate and multivariate analyses. Two experiments were performed. In the first one microcuttings from seedings of 'Rugoso Florida' lemon were inoculated in test tubes with WPM basal medium at different concentrations (1/1, 1/2 and 1/4) supplemented with 0 , 12.5, 25 and 50 g.L-1 of sucrose, solidified with 7.0 g.L-1 of agar and maintained in a growth chamber under controlled conditions for 360 days. In the second experiment, microcuttings of seedling from ten citrus accessions from AGB (Active Germplasm Bank of Citrus) were inoculated in test tubes with WPM supplemented with 25 g.L-1 of sucrose, solidified with 7 g.L-1 agar and maintained under three different incubation conditions for 180 days. The experiments were performed in a completely randomized design with 15 replications in factorial scheme (3 x 4) and (10 x 3), respectively. The univariate and multivariate analyses were performed and provide useful information to studies on in vitro conservation. The WPM medium in the original concentration supplemented with 25 g.L-1 of sucrose was effective in reducing the metabolism of the plants from ‘Rugoso Florida' lemon. The incubation condition with the temperature of 22 ± 1 C, 10 μmol.m-2.s-1 of density light and photoperiod of 12h was the most suitable for in vitro conservation of the evaluated accessions and was efficient to establish minimum growth conditions and healthy plants.