Efeito de diferentes fontes de fitorreguladores na morfogênese de diferentes procedências e explantes de Jatropha curcas L. cultivados in vitro

Abstract

Jatropha curcas is a forest specie that belongs to Euphorbiaceae family and is popularly known as physic nut. Despite having high potential for biodiesel production, there is little information and studies about the type, including the potential for vegetative propagation. To this end, the aim of the study were the establishment in vitro under aseptic conditions of different explants (epicotyls, hypocotyls, rootlets and cotyledons) of Jatropha curcas in culture medium for multiplication from seeds of five provenances germinated in vitro. At the first experiment, the seeds were germinated in culture medium Murashige and Skoog (MS) with half strength of nutrients and without addition of sucrose, which were evaluated disinfestation and germination of seeds from each origin. This experiment was conducted in completely randomized design. After germination, the parts of each seedling were transferred to complete culture medium Murashige and Skoog (MS) with different sources and concentrations of growth regulators (benzylaminopurine, kinetin, thidiazuron, adenine sulfate and indol butiric acid), interconnected, being this the second experiment, where were evaluated contamination and oxidation of explants as well as qualitative and quantitative parameters, such as bud and callus induction, color of buds and callus, callus texture, size and number of buds and fresh and dry weight. This experiment was conducted in completely randomized design with factorial arrangement. In the first experiment, the disinfection was effective in only two of the five origins that were studied, and the contamination was mainly by fungi and bacteria also, with a percentage of the origins of contamination ranging from 0 to 85%; germination happens in two of five origins, and the percentages of germination ranged from 0 to 99,17%. In the second experiment, could be verified that both oxidation and contamination of the explants happened in the seventh day of cultivation, with statistical difference between the origins, combinations of growth regulators and explant sources for both evaluations. The percentage of explants that induced buds and callus varied significantly for origins, combinations of growth regulators and sources of explants. The color of buds ranged from green to yellow, the color of callus ranged from cream, green and brown, and the texture of callus ranged from compact and friable, all statistically different for origins, combinations of growth regulators and sources of explant. As to quantitative analysis, the number of buds that showed the best results, in general, happened for the origin Santa Vitoria – MG, to the combination of growth regulators composed by MS medium with addition of 27.8 μM of BAP and 0.5 μMof IBA, and for cotyledonary explants, with an average of formation of shoots per explant of 5.02, 10.92 and 7, respectively. As for the size of the shoots, this ranged from small seedlings (less than 0.1 cm), medium (between 0.1 and 1 cm) and large (greater than 1 cm), in which the majority of the shoots had small size. For the variables fresh weight and dry weight, there was statistical difference for origins, combinations of growth regulators and sources of explant, being the results, in general, presented for the origin Janaúba – MG, for the combination of growth regulators compound by MS medium supplemented with 27.8 μM of BAP and 0.5 μM of IBA, and for hypocotyls explants type.