| dc.description.abstract | Heart of palm (Euterpe edulis Martius) is a characteristic species of Atlantic Forest. Presently, natural populations are being drastically reduced due to human action. This system of exploitation resulted in substantial genetic erosion in the populations and did not permitted the maintenance of the demographic structure through natural regeneration. The only way of heart of palm propagation was through seeds that do not tolerate storage for a long time. Then, the development of strategies for germplasm conservation has become necessary. Heart of palm does not present a natural system of vegetative propagation, then the technique of culture of tissues showed to be adequated for the conservation and multiplication of germplasm in large scale. The information of geographic distribution of genetic resources is fundamental in the formulation of strategies of in situ conservation and also to help in the collection of vegetal material and to establish ex situ germplasm banks. The main goal of this study was to elucidate some aspects of somatic embryogenesis and analyze the in vitro germination of immature zygotic embryos of heart of palm, aiming the ex situ conservation of germplasm of this species. In the first study, zygotic embryos and leaf sheaths were the explant sources. Zygotic embryos were inoculated in MS culture medium (MURASHIGE and SKOOG, 1962) supplemented with Morel vitamins (MOREL and WETMORE, 1951) 2,4-D (0, 30, 35, 40 mg.L-1), 3 mg.L-1 of 2iP, 0.5 g.L-1 of glutamine, 0.5 g.L-1 of activated charcoal, 30 g.L-1 of glucose and 5 mg.L-1. The delineate used in this study was in Random Blocks, in that the treatments consisted of four concentrations of 2,4-D, combined with two sources of carbohydrate in factorial scheme (4x2), in six repetitions. Each parcel was constituted by two test tubes, each one with one embryo. Leaf sheaths extracted of in vitro germinated plants were inoculated in MS medium supplemented with Picloram (72.3 mg.L-1) or 2,4-D (66.3 mg.L-1), 3 mg.L-1 of 2iP, glutamine (0; 0.29; 0.58; 1.17 g.L-1), 1.5 g.L-1 de activated charcoal and 2.5 g.L-1 of Phytagel. The delineate was in Random Blocks with eight treatments and three repetitions. Each parcel was constituted by three Petri plates in ten transversal sections of leaf sheaths. Indirect somatic embryos were induced from zygotic embryos in a medium
supplemented with 40 mg.L-1 of 2,4-D and 30 g.L-1 of sucrose. It was verified a high formation of leaf sheaths by using MS medium supplemented with 1.17 g.L-1 of
glutamine and 66.3 mg.L-1 of 2,4-D. In the second study, the objective was to elucidate the influence of saline concentration and of sucrose in the culture medium
during the germination of zygotic embryos and to study the influence of the addition of different concentration of Calcium chloride to the MS medium of culture in the induction of somatic embryogenesis from immature zygotic embryos of E. edulis. The evaluation of germination in vitro of zygotic embryos of E. edulis occurred through the inoculation in medium of culture added by Morel vitamins, 7 g.L-1 of agar and 1.5 g.L-1 of activated charcoal. The treatments were different concentrations of the mediums MS (MS and MS/2) combined with different concentrations of sucrose (20, 30 and 40 g.L-1). It was used the Random Blocks Delineate, with six repetitions, each one constituted by five test tubes with one embryo per tube. For the induction of somatic embryogenesis, immature zygotic embryos were extracted and inoculated in a culture medium MS supplemented with Morel Vitamins, 7 g.L-1 of agar, 0.5 g.L-1 of glutamine, 3 mg.L-1 of 2iP, 100 mg.L-1 of 2,4-D and 1.5 g.L-1 of activated charcoal and different concentrations of calcium chloride (0, 2, 4, 8, 12 mM). It was used the statistical delineate in Random Blocks with six repetitions. Each parcel was constituted by one flask containing four immature zygotic embryos. For the conversion of the somatic embryos in seedlings it was used the complete medium of culture MS and the medium with the half of original saline concentration (MS/2). It was verified that the concentration was not affected by the saline concentration of the medium culture and of sucrose. But the growing in height and the production of fresh mass of the seedlings were affected by the treatments. The increasing of concentration of sucrose of 20 to 40 g.L-1 in the medium culture resulted in an increasing in the fresh mass of the seedlings. The composition of the different mediums of culture did not influence the mean number of roots per seedling of heart of palm. The induction of somatic embryogenesis in immature zygotic embryos was not significantly influenced by the addition of different concentrations of calcium chloride to the medium, after 60 days. But, they were observed significant differences among the concentrations of Calcium chloride for the number of somatic embryos formed, after 150 days. The increasing on the concentration of Calcium chloride in the medium of culture resulted in a decrease in the mean number of somatic embryos produced per experimental unit. Both medium MS and MS/2 did not differ significantly in the capacity of germination of the somatic embryos. The process of induction of somatic embryogenesis in the immature zygotic embryos of E. edulis occurred directly from the cotyledonary node of the embryo. The present study evidenced that the supplementation of the medium of culture (MS or MS/2) with sucrose (30 or 40 g.L-1) was necessary for the growing of the seedlings of heart of palm originated from immature zygotic embryos. The results confirmed the possibility to propagate the palm E. edulis through direct somatic embryogenesis, because they were produced complete seedlings, and the importance of supplementation of the medium of culture with a source of organic nitrogen in the in vitro morphogenesis of leaf sheaths of heart of palm. | |
