Cultivo in vitro e criopreservação de estrelícia

Abstract

Streltzia (Strelitzia reginae) is an ornamental plant used as a cut flower and in landscaping. However, specie propagation is limited by the chemical and physical dormancy of the seeds and by the number of shoots formed, thus, in vitro propagation is an alternative for the reproduction of this species. However, in vitro produced seedlings may present limitations during acclimatization, it is necessary to develop a methodology to optimize these step. In addition, the flower trade is marked by trends, requiring the development of techniques for the conservation of germplasm. Among the techniques that can be used, cryopreservation can be used for the long-term conservation of the species, being necessary to know about the effects on the genetic stability and anatomical aspects of the plants. The objective was to evaluate how GA3 and temperature affect the in vitro development of zygotic embryos, as well as the effect of BAP and TDZ on multiplication, the use of coloured shade nets during acclimatization and the effect of cryopreservation in the development, anatomy and genetic stability of streliztia. Greater germination (72%) and shoot length (3.14 cm) were observed with the use of 20 μM of GA3. In this concentration there was an increase in nitrate reductase activity, without altering the genetic stability. The temperature influenced plant growth, which was higher at 25ºC and also in the SOD and APX activity, which were higher at 30ºC. The results showed that 20 μM BAP provided a higher shoot formation, however, these showed a reduction in length, as well as increased oxidation of the medium since TDZ did not induce shoots. During acclimatization, the highest survival rate occurred for plants maintained without coloured shade nets and during cryopreservation, silica gel dehydration for 30 minutes was efficient for better seedling development, with no anatomical changes and changes in genetic stability. So, it is recommended for the cultivation of zygotic embryos, the addition of 20 μM of GA3 and maintenance at the temperature of 25°C, and for the multiplication 20 μM of BAP is efficient and acclimatization must be performed in the absence of coloured shade nets and for cryopreservation, dehydration should be performed for 30 minutes on silica gel.