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ABSTRACT. Micropropagation is an important tool for the multiplication of native Cerrado species. However, understanding the responses of these species under in vitro culture conditions is still incomplete. Thus, the present study aimed to analyze the growth, anatomical behavior and physiology of Pouteria gardneriana cultivated in vitro under photoautotrophic conditions. Nodal segments were cultured at photosynthetic photon flux densities (PPFD) of 75, 100 and 150 μmol m de sacarose. Após 60 dias de cultivo in vitro observou-se regeneração de plântulas de P. gardneriana apenas quando a sacarose estava presente no meio de cultivo. Maior massa fresca e seca, maior espessura do parênquima paliçádico e diâmetro polar e equatorial foram observadas nas plântulas cultivadas no PPFD de 150 μmol m -2 s -1 . As diferentes PPFD utilizadas neste estudo foram suficientes para compreender o comportamento desta espécie in vitro.Palavras-chave: Cerrado, fotoautotrofismo, Sapotaceae.

ABSTRACT. Babassu is a highly productive oil plant that is propagated from seed. Therefore, tissue culture techniques are of great importance because propagation is accelerated. The objective of this study was to evaluate the effect of growth regulators, NAA, BAP, and KIN, on in vitro germination and on the growth of babassu zygotic embryos. Three trials were conducted. For trial (I), the interaction between NAA (0, 1, and 2 μM) and KIN (0, 1, and 2 μM) were studied; for trial (II), the interactions among NAA (0, 1, and 2 μM), KIN (0, 1, and 2 μM), and BAP (1 μM) were studied; and for trial (III), the interactions among NAA (0, 1, and 2 μM), KIN (0, 1, and 2 μM), and BAP (2 μM) were studied. At 30, 60, 90, and 120 days of culture, we assessed average seedling height, and at 120 days, we assessed germination, the germination speed index, cotyledonary petiole growth, oxidation, and the formation of shoots, roots, and calluses. The best results for cotyledonary petiole formation and average seedling height were obtained when using 1 μM of BAP in the culture medium. We also found that the 2 μM of NAA favored root formation.Keywords: Orbignya oleifera (Burret.), biodiesel, Arecaceae. Germinação in vitro de babaçu: influência de reguladores de crescimento em embriões zigóticosRESUMO. O babaçu é uma palmeira oleaginosa, que se propaga via sementes. A contribuição das técnicas de cultura de tecidos é de grande importância, pois acelera sua propagação. Objetivou-se com este trabalho avaliar o efeito dos reguladores NAA, BAP e KIN na germinação e no crescimento in vitro de embriões zigóticos de babaçu. Para isso foram feitos três ensaios: Ensaio (I) interação de NAA (0, 1 e 2 μM) e KIN (0, 1 e 2 μM); Ensaio (II) interação de NAA (0, 1 e 2 μM), KIN (0, 1 e 2 μM) e BAP (1 μM); Ensaio (III) interação de NAA (0, 1 e 2 μM), KIN (0, 1 e 2 μM) e BAP (2 μM). Aos 30, 60, 90 e 120 dias de cultivo, avaliou-se o comprimento médio das plântulas e aos 120 dias germinação, índice de velocidade de germinação, crescimento do pecíolo cotiledonar, formação de parte aérea, raiz, calos e oxidação. Verificou-se que os melhores resultados para formação do pecíolo cotiledonar e o comprimento médio de plântulas foram obtidos com a utilização de 1 μM de BAP no meio de cultivo, e que a concentração de 2 μM de NAA favoreceu a formação de raízes. Palavras-chave:Orbignya oleifera (Burret.), biodiesel, Arecaceae.

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The babassu (Orbignya oleifera Burret) is a palm that contains oilseeds whose biomass can be used for biofuel production. Due to difficulties in germinating the species, in vitro cultivation techniques are sought as a viable alternative to expand studies on germination. The objective of this study was to evaluate different types of tube caps for in vitro growth of babassu seedlings. Thus, zygotic embryos were inoculated in tubes containing MS medium with a 50% salt concentration, which were sealed with diferent caps, a cotton plug, plastic cap, PVC film and plastic cap with PVC film. During the in vitro culture, the mean length of seedlings, the formation of the cotyledon petiole and root, as well as oxidation of the explants were evaluated. The cotton plug exhibited a positive effect on the initial steps of in vitro cultivation, which promoted more vigorous plants with greater mean lengths; however, its effect decreased as the cultivation time increased. The cotton plug is an alternative and eight-fold less expensive than a conventional plug, which favors early in vitro growth of O. oleifera Burret.