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Germination of Encholirium spectabile *** Schult.&*** in Response to Temperature and Water Stress

American Journal of Plant Sciences 2014年第15期5卷 2237-2246页

作者： Marlene Feliciano Figueiredo Francisco Carlos Barboza Nogueira Charles Lobo Pinheiro selma freire de brito Sebastiao Medeiros Filho University of Vale do Acarau—UVA Campus BetaniaCity of SobralBrazil Seed Analysis Laboratory Department of PhytotecnicFederal University of Ceara—UFCCampus do PiciCity of FortalezaBrazil

A study was conducted to examine the effects of different temperatures and water stress on Encholirium spectabile seeds. We evaluated the germination percentage, speed and time of germination of small (4.01 mm), at temperatures of 15°C, 20°C, 25°C, 30°C, 35°C, 40°C and 45°C and a photoperiod of 12 hours of light. Seeds were subjected to osmotic potentials of 0, -0.2, -0.4, -0.6, -0.8, -1.0, -1.2 and -1.4 MPa, induced by solutions of polyethylene glycol. The results indicated an excellent germination of medium and large seeds at the temperatures of 20°C, 25°C, 30°C and 35°C. The temperature of 35°C provided the best mean germination time of large seeds and a higher speed rate of medium and large seeds. E. spectabile seeds germinate in a wide range of water deficit of -0.2 to -1.2 MPa. Germination reduced at concentrations of -1.0 and -1.2 MPa. No germination occurred at -1.4 MPa. Larger seeds showed the higher germination potential than medium and small seeds at the temperatures of 25°C, 30°C and 35°C and in the range ofwater deficit of -0.2 to -1.2 Mpa.

关键词： Seeds Size Native Species Osmotic Potential Polyethylene Glycol Semiarid Region

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Piptadenia stipulacea(Benth.)Ducke Seed Germination in Response to Temperature,Light and Water Stress

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American Journal of Plant Sciences 2014年第26期5卷 3796-3904页

作者： Francisco Carlos Barboza Nogueira Maria Luiza Bezerra Charles Lobo Pinheiro selma freire de brito Sebastiao Medeiros Filho Brazilian Institute of Environment and Renewable Natural Resources—IBAMA City of FortalezaBrazil Seed Analysis Laboratory(LAS—Laboratorio de Analise de Sementes) Plant Science DepartmentFederal University of Ceara(UFC)Campus of PiciCity of FortalezaBrazil

The current study aimed to investigate the effects of the temperature, light, and water stress on Piptadenia stipulacea seed germination. It assessed germination percentage, speed and average germination time, root and stem length as well as the dry weight of seedlings subjected to the constant temperatures of 20°C, 25°C and 30°C and alternating temperatures from 20°C to 30°C. A 12-hour photoperiod was established in addition to the following light conditions: white, darkness, red and far red. The experimental design was completely randomized and four replicates of 25 seeds were performed for each treatment. Regarding water stress, seeds were subjected to osmotic potentials of 0, -0.2, -0.4, -0.6, -0.8, -1.0, and -1.2 MPa, at 30°C and 12 h light/12 h darkness photoperiods. After they were mixed, 100 seeds were randomly selected for biometric measurement and they were found to be uneven with respect to size and weight. P. stipulacea seeds germinated under all tested temperature and light conditions. Germination under water stress occurred up to -0.8 MPa. The conclusion is that there was no germination from -1.0 MPa. The seeds are light-indifferent and germinate at the constant temperatures of 20°C, 25°C and 30°C and alternating temperatures from 20°C to 30°C.

关键词： Forest-Tree Seeds Native Species Semi-Arid Region Polyethylene Glycol

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Seed Priming and Tolerance to Salt and Water Stress in Divergent Grain Sorghum Genotypes

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American Journal of Plant Sciences 2018年第4期9卷 606-616页

作者： Charles Lobo Pinheiro Hellen Thayse Nascimento Araújo selma freire de brito Marcos da Silva Maia Jesimiel da Silva Viana Sebastiao Medeiros Filho department of Plant Science Federal University of CearáFortalezaBrazil

Tolerance to water and salt stress during germination and growth of agricultural species might have superior results when seeds are submitted to priming processes. The objective of the present study was to evaluate the use of hydropriming and hormonal priming with gibberellic acid (GA3) on the tolerance of divergent genotypes of sorghum to salt and water stress during germination and seedling growth. The genotypes analyzed were cultivar BRS 330 and lineage 201420, which are the most and least tolerant to water and salt stress, respectively. Sowing was undertaken under control (no stress), water stress (-0.6 MPa), and salt stress (20 dS·m-1) conditions, and the seeds were subjected to the following treatments: control-no immersion;hydropriming-immersion for 2 hours in distilled water;and hormonal priming-immersion in GA3 solutions, at concentrations of 50, 75, and 100 ppm, for 2 hours. After soaking, the seeds were dried for 24 hours at a temperature of 30°C ± 2°C. The variables analyzed were percentage and germination speed index, root and shoot lengths, and root/shoot ratio. The stress conditions analyzed negatively affected the two genotypes;however, the seeds that underwent priming processes improved the performance of the genotypes under salt and water stress conditions, especially when using seeds of the more tolerant genotype (BRS 330) subjected to hormonal priming at 100 ppm GA3 concentration.

关键词： Hydropriming Hormonal Priming Gibberellic Acid Sorghum bicolor

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The Thermal Stability of (CaTiO₃)1-x (Cr_3/4Fe_5/4O₃)_x Ceramic Composites in the Microwave Region

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Materials Sciences and Applications 2016年第4期7卷 202-209页

作者： Francisco Nivaldo Aguiar freire Manoel Roberval Pimentel Santos Hélio Henrique Barbosa Rocha Ana Fabiola Leite Almeida selma Elaine Mazzetto Antonio Jefferson Mangueira Sales Antonio Sergio Bezerra Sombra department of Mechanical Engineering Federal University of Ceara Campus do Pici Fortaleza Brazil Western Para Federal University (UFOPA) Santarem Brazil department of Organic and Inorganic Chemistry Federal University of Ceara Campus do Pici Fortaleza Brazil department of Physics Federal University of Ceara Campus do Pici Fortaleza Brazil

The thermal stability, structural and dielectric properties of the (CaTiO3)1-x(Cr3/4Fe5/4O3)x ceramic composites with x = 0, 0.1, 0.5, 0.9 and 1 have been examined in microwave region. The samples were produced via the solid-state reaction. The orthorhombic structural phase of CaTiO3 and trigonal structural phase of Cr3/4Fe5/4O3 were confirmed by the X-Ray Powder Diffraction (XRPD). The XRPD patterns for composites reveal the quantities of each original phase present. The infrared spectra of the samples reinforce this structural verification indicating no or minimal occurrence of unwanted reactions. The first sample (x = 0) and last sample (x = 1) in this series exhibit the maximum and the minimum of the relative dielectric permittivity and values range from 140.1 to 8.3 respectively. The measured temperature coefficient of the matrix CaTiO3 was +921 ppm·℃-1 and for the matrix Cr3/4Fe5/4O3 was -56 ppm·℃-1. With the study of series of composites, it was possible to make a mathematical prediction for a composition reach the temperature coefficient near zero. The proposed ceramic has potential use as thermostable material in the microwave region and can be applied to resonators, low-noise amplifiers, filters, and so on.

关键词： Ceramics Composites Dielectric Properties

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