RESUMO Citogenética e identificação da região organizadora nucleolar em Heliconia bihai (L.) L.O gênero Heliconia é pouco estudado e o número de espécies existentes é incerto, compreendendo entre 150 e 250 espécies. No Brasil, cerca de 40 espécies ocorrem naturalmente e são conhecidas por vários nomes. Esta pesquisa teve como objetivo a caracterização morfométrica e a identificação da NOR (regiões organizadoras de nucléolos ativos), pelo bandeamento Ag-NOR dos cromossomos de Heliconia bihai (L.) L. Foram utilizados meristemas radiculares, submetidos ao tratamento de bloqueio em solução de amiprofos-metil (APM), fixados em solução de (metanol-ácido acético), por, no mínimo, 24 horas. Os meristemas foram lavados em água destilada e submetidos à digestão enzimática, com a enzima pectinase. As lâminas foram confeccionadas por dissociação do meristema radicular, secadas ao ar e, em seguida, em placa aquecedora, a 50 ºC. Subsequentemente, algumas lâminas foram submetidas ao corante Giemsa 5%, para confecção do cariótipo, e à solução de nitrato de prata (AgNO 3 ) 50%, para o bandeamento Ag-NOR. A espécie H. bihai apresenta 2n = 22 cromossomos, quatro pares de cromossomos submetacêntricos e sete pares de cromossomos metacêntricos, classificados de médio a curtos (3.96 à 0.67 µm), com presença de NOR ativa nos pares (1 e 2) e células interfásicas com dois nucléolos. Estas características são de espécie diploide.Palavras-chave: AgNO 3 , amiprofos-metil, cariótipo, heliconeaceae, morfometria. Cytogenetic and identification of the nucleolus organizer region inHeliconia bihai (L.) L. 1The genus Heliconia is not much studied and the number of existing species in this genus is still uncertain. It is known that this number relies between 150 to 250 species. In Brazil, about 40 species are native and known by many different names. The objective of this paper was to characterize morphometrically and to identify the NOR (active nucleolus organizer regions) by Ag-NOR banding of chromosomes of Heliconia bihai (L) L. Root meristems were submitted to blocking treatment in an amiprofos-methyl (APM) solution, fixed in methanol-acetic acid solution for 24 hours, at least. The meristems were washed in distilled water and submitted to enzymatic digestion with pectinase enzyme. The slides were prepared by dissociation of the root meristem, dried in the air and also on hot plate at 50°C. Subsequently, some slides were submitted to 5% Giemsa stain for karyotype construction and to a solution of silver nitrate (AgNO 3 ) 50% for Ag-NOR banding. The species H. bihai has 2n = 22 chromosomes, 4 pairs of submetacentric chromosomes and 7 pairs of metacentric chromosomes, and graded medium to short (3.96 to 0.67 µM), with the presence of active NOR in pairs 1 and 2 and interphase cells with 2 nucleoli. These are the features of a diploid species.
Methodologies for imposing stress and reproducible results are a bottleneck for breeding programmes, and this is due to the lack of consensus between the existing methodologies. The aim of the present study was to propose and validate a new methodology for imposing water deficit in soybean that allows the identification of water deficit-tolerant genotypes, at different harvest times and phenological stages.The methodology was based on the construction of a water retention curve in the soil to determine the water stresses that indicate the field capacity and the permanent wilt point and, thus, define the water regime in the conditions of control and stress. Seven trials were carried out to validate the methodology. In trials 1, 2, 3, 4, 5 and 6, the water deficit was imposed in the reproductive phase and the components of production were evaluated. In addition to these variables, leaf water potential was evaluated in trial 6. In trial 7, the plants were subjected to water deficit in the vegetative phase and the morphological traits were evaluated. The efficiency of the methodology was confirmed by the distinction between the conditions of control and stress, affirmed by the statistical differences in most of the traits evaluated in the reproductive and vegetative phases.
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This study aims to evaluate the effect of IBA concentrations and microcuttings successive collections in the micropropagation of Eucalyptus grandis x E. urophylla and Eucalyptus urophylla x E. globulus clones. Clumps containing six to eight buds of clones established in vitro were transferred to a 250 mL glass flask in JADS semisolid medium. Successive collections were performed every 20 days for Eucalyptus grandis x E. urophylla clone and every 30 days for Eucalyptus urophylla x E. globulus clone. The following variables were evaluated under in vitro conditions: number of shoots > 0.5 cm, number of microcuttings > 2 cm, length of the longest microcutting, and shoots vigor. Under ex vitro conditions, in the greenhouse and shade house, the following variables were evaluated: seedling height, percentage of survival, stem diameter, percentage of root observed at the lower end of the tube, and seedling vigor. In full sun (ex vitro), the following variables were analyzed: seedling height, stem diameter, survival, number of roots, root volume, seedling vigor, and shoot and root dry matter. Good in vitro microcuttings productivity was observed over the successive collections. IBA levels were adjusted for each clone, ranging from 0.25 to 0.50 mg L-1 for Eucalyptus grandis x E. urophylla clone, and from 0.75 to 1.0 mg L-1 for Eucalyptus urophylla x E. globulus clone. IBA concentrations led to residual effects under ex vitro conditions, providing good rooting and survival for Eucalyptus grandis x E. urophylla and Eucalyptus urophylla x E. globulus clones at IBA concentrations between 0.25 and 0.50 mg L-1 and between 0.50 and 1.0 mg L-1, respectively.
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