Two-wavelength switching with a distributed-feed back semiconductor optical amplifier (DFBSOA)

Switching of a signal beam by another control beam at different wavelength is demonstrated experimentally using the optical bistability occurring in a 1.55 mm-distributed feedback semiconductor optical amplifier (DFBSOA) working in reflection. Counterclockwise (S-shaped) and reverse (clockwise) bistability are observed in the output of the control and the signal beam respectively, as the power of the input control signal is increased. With this technique an optical signal can be set in either of the optical input wavelengths by appropriate choice of the powers of the input signals. The switching properties of the DFBSOA are studied experimentally as the applied bias current is increased from below to above threshold and for different levels of optical power in the signal beam and different wavelength detunings between both input signals. Higher on-off extinction ratios, wider bistable loops and lower input power requirements for switching are obtained when the DFBSOA is operated slightly above its threshold value.

Experimental and numerical investigation of effect of sawn timber dimensions in ultrasonic velocity measurements of Spanish softwoods

Ultrasonic sound velocity measurements with hand-held equipment remain due to their simplicity among the most used methods for non-destructive grading of sawn woods, yet a dedicated normalization effort with respect to strength classes for Spanish species is still required. As part of an ongoing project with the aim of definition of standard testing methods, the effect of the dimensions of commonly tested Scots pine (Pinus sylvestris L.) timbers and equipment testing frequency on ultrasonic velocity were investigated. A dedicated full-wave finite-difference time-domain software allowed simulation of pulse propagation through timbers of representative length and section combinations. Sound velocity measurements vL were performed along the grain with the indirect method at 22 kHz and 45 kHz for grids of measurement points at specific distances. For sample sections larger than the cross-sectional wavelength ?RT, the simulated sound velocity vL converges to vL = (CL/?)0.5. For smaller square sections the sound velocity drops down to vL = (EL/?)0.5, where CL, EL and ? are the stiffness, E-modul and density, respectively. The experiments confirm a linear regression between time of flight and measurement distance even at less than two wavelength menor que2?L distance, the fitted sound speed values increased by 15% between the two tested frequencies.

Asociación entre caracteres biométricos y calidad fisiológica en semillas de tomate (Solanum lycopersicum L.)

La clasificación de las semillas de especies olerícolas se realiza principalmente por peso y tamaño, con criterios similares a los aplicados en cereales y leguminosas, en que se asocia positivamente estos atributos físicos con la calidad fisiológica. No obstante lo anterior, en diversas especies de hortalizas la información es escasa y contradictoria al respecto, lo que motiva la realización de la presente investigación. En semillas de tomate (Solanum lycopersicum L.) se determinó el efecto del peso y tamaño sobre la calidad fisiológica expresada como germinación y vigor. Además, se correlacionaron los resultados de las pruebas de evaluación de calidad fisiológica y se describieron variables del crecimiento y desarrollo. Se utilizaron lotes de diferentes variedades de semillas híbridas de cuatro temporadas, producidas en un clima templado cálido con lluvias invernales y estación seca prolongada (32º 54’ y 34° 21´ latitud Sur). Se midió peso y tamaño de semillas, además en dos temporadas se evaluaron las características internas de área y peso de embrión y área de endospermo. Se determinó la calidad de las semillas con la prueba de germinación y según fuera el año de estudio se midió vigor con las pruebas de envejecimiento acelerado, de plantas útiles al trasplante y de plántulas emergidas. Con análisis de imágenes y rayos X se extrajeron datos del tamaño externo e interno de las semillas y plántulas. Los lotes se compararon mediante análisis de varianza y las medias con la prueba de Tukey, la asociación entre dos variables se determinó con correlaciones de Pearson, las variables de peso y tamaño de la semilla y su relación con las pruebas de calidad, se analizaron mediante regresiones múltiples. Se utilizó un nivel de significación de 0,05 de probabilidad. Los resultados indicaron que el tamaño y no el peso de las semillas de tomate, diferenciaron calidad entre lotes en las diversas variedades. La prueba de germinación tuvo una baja sensibilidad para discriminar lotes, además de una escasa correlación con las características físicas de las semillas, cuando hubo asociación, la relación fue débil y negativa. La prueba de vigor de envejecimiento acelerado diferenció lotes y presentó escasa asociación con las características físicas de las semillas. El número de semillas germinadas en la prueba de envejecimiento acelerado se explicó por el efecto del tamaño de las semillas, mientras que las fracciones de descarte se asociaron con el peso de las mismas. La prueba de vigor de plantas útiles al trasplante no discriminó entre lotes. Tuvo una asociación débil con el peso y tamaño de las semillas. El modelo asociado a esta relación explicó con un alto coeficiente de determinación que el peso de la semilla influyó sobre la emergencia temprana, mientras que la relación fue menor y negativa con plantas de mayor desarrollo. La prueba de vigor de plántulas emergidas discriminó lotes de semillas con plántulas de 3 a 5 días después de siembra. Hubo escasa y débil asociación entre esta prueba y las características de peso y tamaño las semillas. El modelo de predicción de plántulas emergidas fue particular en cada temporada, cuando hubo un coeficiente de determinación alto influyó negativamente el peso o tamaño de la semilla. Entre las pruebas de calidad fisiológica evaluadas en semillas de tomate hubo escasas correlaciones significativas. Entre germinación y vigor las correlaciones significativas fueron débiles y sólo se encontraron en algunas temporadas de evaluación. Entre las pruebas de vigor no hubo asociación. En las pruebas de vigor de plantas útiles al trasplante y de plántulas emergidas, los cotiledones alcanzaron el mayor porcentaje de materia seca y se correlacionaron fuertemente con la materia seca total. En la prueba de plántulas emergidas la materia seca de las radículas diferenció parcialmente lotes de semillas al igual que la longitud total y de las radículas. La longitud de la radícula se correlacionó fuertemente con la longitud total de plántulas. ABSTRACT Seed selection for olericultural species is mainly carried out considering weight and size with similar criteria to those applied in cereals and legumes where size and physiological quality are favorably associated. However, information about several species is limited and contradictory regarding the above, leading to the present research. In tomato (Solanum lycopersicum L.) seeds, the effect of weight and size on the physiological quality expressed as germination and vigor was determined. In addition, results of quality evaluation tests were correlated and variables of growth and development were described. Batches of hybrid seeds from four seasons were used. These seeds were produced in a mild warm climate with winter rainfalls and long dry season (32º 54’ and 34° 21´South Latitude). Seed weight and size were determined, additionally internal characteristics such as embryo area and weight as well as endosperm area were evaluated in two seasons. The quality of seeds was established using the germination test and, depending on the year of the study, vigor was measured through accelerated aging tests for plants useful for transplanting and emerged seedlings. Using imaging analysis and X rays, data regarding external and internal size of seeds and seedlings were obtained. Batches were compared through ANOVA and means using Tukey’s test; the association between both variables was determined with Pearson correlations, whereas variables of seed weight and size and their relation to quality tests were analyzed through multiple regressions. A significance level of 0.05 probability was used. Results showed that the size (but not the weight) of tomatoes differentiates quality between batches from several seasons. The germination test was not sensitive enough to discriminate batches in addition to having a limited correlation with the characteristics of seeds, when they were associated, the relation was weak and unfavorable. Vigor test for accelerated aging made the difference between batches and presented low association with physical characteristics of the seeds. The number of germinated seeds in the accelerated aging test was explained by the effect of the seed size, whereas cull fractions were associated with their weight. The vigor test of plants useful for transplanting did not discriminate between batches. The association with seed weight and size was weak. The model associated to this relation explained, with a high coefficient determination, that the seed weight had influence on early emergence, whereas the relation was minor and unfavorable with more developed plants. Vigor test of emerged seedlings discriminated batches of seeds with seedlings of 3 to 5 days after sowing. There was a limited and weak association between this test and the characteristics of seed weight and size. The prediction model for seedlings emerged was particular in each season, when the determination coefficient was high, seed weight and size influenced negatively. Among the physiological quality tests evaluated in tomato seeds, significant correlations were negligible. Between germination and vigor, significant correlations were poor, being only found in some evaluation seasons. There was no association in the vigor tests. In vigor tests for plants useful for transplanting and emerged seedlings, cotyledons reached the highest percentage of dry matter and were strongly correlated with total dry matter. In the test of emerged seedlings, dry matter of radicles partially differentiated batches of seeds as well as total length and radicles. Radicle length was strongly correlated with total seedlings length.

Arabidopsis thaliana DOF6 negatively affects germination in non-after ripened seeds and interacts with TCP14

Seed dormancy prevents seeds from germinating under environmental conditions unfavourable for plant growth and development and constitutes an evolutionary advantage. Dry storage, also known as after-ripening, gradually decreases seed dormancy by mechanisms not well understood. An Arabidopsis thaliana DOF transcription factor gene (DOF6) affecting seed germination has been characterized. The transcript levels of this gene accumulate in dry seeds and decay gradually during after-ripening and also upon seed imbibition. While constitutive over-expression of DOF6 produced aberrant growth and sterility in the plant, its over-expression induced upon seed imbibition triggered delayed germination, abscisic acid (ABA)-hypersensitive phenotypes and increased expression of the ABA biosynthetic gene ABA1 and ABA-related stress genes. Wild-type germination and gene expression were gradually restored during seed after-ripening, despite of DOF6-induced over-expression. DOF6 was found to interact in a yeast two-hybrid system andin planta with TCP14, a previously described positive regulator of seed germination. The expression of ABA1 and ABA-related stress genes was also enhanced in tcp14 knock-out mutants. Taken together, these results indicate that DOF6 negatively affects seed germination and opposes TCP14 function in the regulation of a specific set of ABA-related genes

The relevance of seed size in modulating leaf physiology and early plant performance in two tree species

he size of seeds and the microsite of seed dispersal may affect the early establishment of seedlings through different physiological processes. Here, we examined the effects of seed size and light availability on seedling growth and survival, and whether such effects were mediated by water use efficiency. Acorns of Quercus petraea and the more drought-tolerant Quercus pyrenaica were sowed within and around a tree canopy gap in a sub-Mediterranean forest stand. We monitored seedling emergence and measured predawn leaf water potential (Ψpd), leaf nitrogen per unit area (Na), leaf mass per area, leaf carbon isotope composition (δ13C) and plant growth at the end of the first summer. Survival was measured on the next year. Path analysis revealed a consistent pattern in both species of higher δ13C as Ψpd decreased and higher δ13C as seedlings emerged later in the season, indicating an increase in 13C as the growing season is shorter and drier. There was a direct positive effect of seed size on δ13C in Q. petraea that was absent in Q. pyrenaica. Leaf δ13C had no effect on growth but the probability of surviving until the second year was higher for those seedlings of Q. pyrenaica that had lower δ13C on the first year. In conclusion, leaf δ13C is affected by seed size, seedling emergence time and the availability of light and water, however, leaf δ13C is irrelevant for first year growth, which is directly dependent on the amount of seed reserves.

Two Novel Methods For The Determination Of The Number Of Components In Independent Components Analysis Models

Independent Components Analysis is a Blind Source Separation method that aims to find the pure source signals mixed together in unknown proportions in the observed signals under study. It does this by searching for factors which are mutually statistically independent. It can thus be classified among the latent-variable based methods. Like other methods based on latent variables, a careful investigation has to be carried out to find out which factors are significant and which are not. Therefore, it is important to dispose of a validation procedure to decide on the optimal number of independent components to include in the final model. This can be made complicated by the fact that two consecutive models may differ in the order and signs of similarly-indexed ICs. As well, the structure of the extracted sources can change as a function of the number of factors calculated. Two methods for determining the optimal number of ICs are proposed in this article and applied to simulated and real datasets to demonstrate their performance.

Isozyme systems as markers of genetic deterioration in stored seeds of Brassicaceae species

The main objective of this study was to determine if isozyme systems can be used as markers of genetic deterioration in Brassicaceae seed accessions under different storage conditions. Seed samples of Brassica oleracea, Cardaria draba, Erysimum cheiri, Iberis sempervirens and Rapistrum rugosum were stored for periods of 9 to 30 years at -10°C and 3-4% seed moisture content (long-term or LT conditions) and at 5°C and uncontrolled relative humidity (RH) (short-term or ST conditions). Starch Gel Electrophoresis (SGE) was used to analyse six enzyme systems oriented to determine the genetic deterioration of the accessions studied. The results obtained show that long-term storage conditions (LT) were extremely effective in maintaining the viability of seeds of the five Brassicaceae species studied. The final germination percentages reached by seeds from LT samples ranged from 75 to 100%, while the germination percentages of ST samples (except for B. oleracea) were very low (from 0 to 10%). Similar conclusions were obtained studying the integrity of electrophoretic bands for several isozymes. Two enzyme systems were of special interest: malate dehydrogenase and alcohol dehydrogenase.

Authentication in mobile devices through hand gesture recognition

This article proposes an innovative biometric technique based on the idea of authenticating a person on a mobile device by gesture recognition. To accomplish this aim, a user is prompted to be recognized by a gesture he/she performs moving his/her hand while holding a mobile device with an accelerometer embedded. As users are not able to repeat a gesture exactly in the air, an algorithm based on sequence alignment is developed to correct slight differences between repetitions of the same gesture. The robustness of this biometric technique has been studied within 2 different tests analyzing a database of 100 users with real falsifications. Equal Error Rates of 2.01 and 4.82% have been obtained in a zero-effort and an active impostor attack, respectively. A permanence evaluation is also presented from the analysis of the repetition of the gestures of 25 users in 10 sessions over a month. Furthermore, two different gesture databases have been developed: one made up of 100 genuine identifying 3-D hand gestures and 3 impostors trying to falsify each of them and another with 25 volunteers repeating their identifying 3- D hand gesture in 10 sessions over a month. These databases are the most extensive in published studies, to the best of our knowledge.

Electron temperature versus laser intensity times wavelength squared: a comparison of theory and experiments

The peak temperature in the corona of plasma ejected by a laser-irradiated slab is discussed in terms of a one-electron-temperature model. Both heat-flux saturation and pulse rise-time effects are considered;the intensity in the rising half of the pulse is approximated by a linear function of time, I(t) = Iot/r. The temperature is found to be proportional to (IQX2)273 and a function of I0X4/r. Above a certain value of I0X4/T, the plasma presents two characteristic temperatures (at saturation and at the critical surface) which can be identified with experimentally observed cold- and hot-electron temperatures. The results are compared with extensive experimental data available for both nd and CO2 lasers, I0(W'cnf2) X2 (/um) starting around 1012. The agreement is good if substantial flux inhibition is assumed (flux-limit factor f = 0.03), and fails for I0X2 above 1O1S. Results for both ablation pressure and mass ablation rate are also given.

Self-consistent resonance absorption with two layer profile steepening

Resonance absorption of p-polarized light, incident at angle 6 on a flowing, stratified plasma, is analyzed; profile steepening within (i) a layer around the turning point, and (ii) a thinner,embedded sublayer at the critical surface is taken into account self-consistently. The entire steepened region is taken as collisionless and isothermal. The structure of the main layer shows a variety of regimes, depending on how the flow crosses a sonic point. The structure of the sublayer is also determined; it is entirely subsonic (with no wave breaking) for a well-defined,broad parameter range. Density changes across both layer and sublayer, and fractional absorption, are given in terms of [(wavelength)2 Xintensity/temperature], and (temperature/mec2). The flow outside the double structure is also analyzed for particular conditions.

Wavelength monitoring with semiconductor laser amplifiers

The semiconductor laser diodes that are typically used in applications of optical communications, when working as amplifiers, present under certain conditions optical bistability, which is characterized by abruptly switching between two different output states and an associated hysteresis cycle. This bistable behavior is strongly dependent on the frequency detuning between the frequency of the external optical signal that is injected into the semiconductor laser amplifier and its own emission frequency. This means that small changes in the wavelength of an optical signal applied to a laser amplifier causes relevant changes in the characteristics of its transfer function in terms of the power requirements to achieve bistability and the width of the hysteresis. This strong dependence in the working characteristics of semiconductor laser amplifiers on frequency detuning suggest the use of this kind of devices in optical sensing applications for optical communications, such as the detection of shifts in the emission wavelength of a laser, or detect possible interference between adjacent channels in DWDM (Dense Wavelength Division Multiplexing) optical communication networks

Usability analysis of authentication techniques

This document will be divided into two main parts. The first one will be the classification of the authentication techniques. We will search the main electronic databases for papers related to authentication techniques. We will then summarize the related papers and show what classifications they use for the authentication techniques. After all of the documents have been read and summarized we will analyse them and group the authentication techniques into the classifications found. For the second part of the document we will focus on the study of usability attributes in the authentication techniques. This to know how authentications techniques compare to one another based on their usability attributes. We will search the main electronic databases for papers related to the usability attributes of authentication techniques based on the usability definition of ISO/IEC 25010 (SQuaRE) and its attributes. We will then summarize the related papers and show what authentication methods they describe and which usability attributes they measure. After all of the documents have been read and summarized we will analyse them depending on their usability attribute. At the end we will elaborate those results to show which authentication techniques have better usability in terms of a specific usability attribute. This will help practitioners who are interested in using authentication methods but want or need to focus on a specific usability attribute. They will be able to use this as a guide to help them chose the best option that fits their purpose.

Biometric authentication of users through iris by using key binding and similarity preserving hash functions = Autenticación biométrica de usuarios a través del iris mediante la ocultación de claves y funciones resumen que preservan la similitud

El extraordinario auge de las nuevas tecnologías de la información, el desarrollo de la Internet de las Cosas, el comercio electrónico, las redes sociales, la telefonía móvil y la computación y almacenamiento en la nube, han proporcionado grandes beneficios en todos los ámbitos de la sociedad. Junto a éstos, se presentan nuevos retos para la protección y privacidad de la información y su contenido, como la suplantación de personalidad y la pérdida de la confidencialidad e integridad de los documentos o las comunicaciones electrónicas. Este hecho puede verse agravado por la falta de una frontera clara que delimite el mundo personal del mundo laboral en cuanto al acceso de la información. En todos estos campos de la actividad personal y laboral, la Criptografía ha jugado un papel fundamental aportando las herramientas necesarias para garantizar la confidencialidad, integridad y disponibilidad tanto de la privacidad de los datos personales como de la información. Por otro lado, la Biometría ha propuesto y ofrecido diferentes técnicas con el fin de garantizar la autentificación de individuos a través del uso de determinadas características personales como las huellas dáctilares, el iris, la geometría de la mano, la voz, la forma de caminar, etc. Cada una de estas dos ciencias, Criptografía y Biometría, aportan soluciones a campos específicos de la protección de datos y autentificación de usuarios, que se verían enormemente potenciados si determinadas características de ambas ciencias se unieran con vistas a objetivos comunes. Por ello es imperativo intensificar la investigación en estos ámbitos combinando los algoritmos y primitivas matemáticas de la Criptografía con la Biometría para dar respuesta a la demanda creciente de nuevas soluciones más técnicas, seguras y fáciles de usar que potencien de modo simultáneo la protección de datos y la identificacíón de usuarios. En esta combinación el concepto de biometría cancelable ha supuesto una piedra angular en el proceso de autentificación e identificación de usuarios al proporcionar propiedades de revocación y cancelación a los ragos biométricos. La contribución de esta tesis se basa en el principal aspecto de la Biometría, es decir, la autentificación segura y eficiente de usuarios a través de sus rasgos biométricos, utilizando tres aproximaciones distintas: 1. Diseño de un esquema criptobiométrico borroso que implemente los principios de la biometría cancelable para identificar usuarios lidiando con los problemas acaecidos de la variabilidad intra e inter-usuarios. 2. Diseño de una nueva función hash que preserva la similitud (SPHF por sus siglas en inglés). Actualmente estas funciones se usan en el campo del análisis forense digital con el objetivo de buscar similitudes en el contenido de archivos distintos pero similares de modo que se pueda precisar hasta qué punto estos archivos pudieran ser considerados iguales. La función definida en este trabajo de investigación, además de mejorar los resultados de las principales funciones desarrolladas hasta el momento, intenta extender su uso a la comparación entre patrones de iris. 3. Desarrollando un nuevo mecanismo de comparación de patrones de iris que considera tales patrones como si fueran señales para compararlos posteriormente utilizando la transformada de Walsh-Hadarmard. Los resultados obtenidos son excelentes teniendo en cuenta los requerimientos de seguridad y privacidad mencionados anteriormente. Cada uno de los tres esquemas diseñados han sido implementados para poder realizar experimentos y probar su eficacia operativa en escenarios que simulan situaciones reales: El esquema criptobiométrico borroso y la función SPHF han sido implementados en lenguaje Java mientras que el proceso basado en la transformada de Walsh-Hadamard en Matlab. En los experimentos se ha utilizado una base de datos de imágenes de iris (CASIA) para simular una población de usuarios del sistema. En el caso particular de la función de SPHF, además se han realizado experimentos para comprobar su utilidad en el campo de análisis forense comparando archivos e imágenes con contenido similar y distinto. En este sentido, para cada uno de los esquemas se han calculado los ratios de falso negativo y falso positivo. ABSTRACT The extraordinary increase of new information technologies, the development of Internet of Things, the electronic commerce, the social networks, mobile or smart telephony and cloud computing and storage, have provided great benefits in all areas of society. Besides this fact, there are new challenges for the protection and privacy of information and its content, such as the loss of confidentiality and integrity of electronic documents and communications. This is exarcebated by the lack of a clear boundary between the personal world and the business world as their differences are becoming narrower. In both worlds, i.e the personal and the business one, Cryptography has played a key role by providing the necessary tools to ensure the confidentiality, integrity and availability both of the privacy of the personal data and information. On the other hand, Biometrics has offered and proposed different techniques with the aim to assure the authentication of individuals through their biometric traits, such as fingerprints, iris, hand geometry, voice, gait, etc. Each of these sciences, Cryptography and Biometrics, provides tools to specific problems of the data protection and user authentication, which would be widely strengthen if determined characteristics of both sciences would be combined in order to achieve common objectives. Therefore, it is imperative to intensify the research in this area by combining the basics mathematical algorithms and primitives of Cryptography with Biometrics to meet the growing demand for more secure and usability techniques which would improve the data protection and the user authentication. In this combination, the use of cancelable biometrics makes a cornerstone in the user authentication and identification process since it provides revocable or cancelation properties to the biometric traits. The contributions in this thesis involve the main aspect of Biometrics, i.e. the secure and efficient authentication of users through their biometric templates, considered from three different approaches. The first one is designing a fuzzy crypto-biometric scheme using the cancelable biometric principles to take advantage of the fuzziness of the biometric templates at the same time that it deals with the intra- and inter-user variability among users without compromising the biometric templates extracted from the legitimate users. The second one is designing a new Similarity Preserving Hash Function (SPHF), currently widely used in the Digital Forensics field to find similarities among different files to calculate their similarity level. The function designed in this research work, besides the fact of improving the results of the two main functions of this field currently in place, it tries to expand its use to the iris template comparison. Finally, the last approach of this thesis is developing a new mechanism of handling the iris templates, considering them as signals, to use the Walsh-Hadamard transform (complemented with three other algorithms) to compare them. The results obtained are excellent taking into account the security and privacy requirements mentioned previously. Every one of the three schemes designed have been implemented to test their operational efficacy in situations that simulate real scenarios: The fuzzy crypto-biometric scheme and the SPHF have been implemented in Java language, while the process based on the Walsh-Hadamard transform in Matlab. The experiments have been performed using a database of iris templates (CASIA-IrisV2) to simulate a user population. The case of the new SPHF designed is special since previous to be applied i to the Biometrics field, it has been also tested to determine its applicability in the Digital Forensic field comparing similar and dissimilar files and images. The ratios of efficiency and effectiveness regarding user authentication, i.e. False Non Match and False Match Rate, for the schemes designed have been calculated with different parameters and cases to analyse their behaviour.

Seed germination characteristics of Phillyrea angustifolia L. and P. latifolia L. (Oleaceae), two Mediterranean shrub species having lignified endocarp

The aim of this study was to determine the germination characteristics of Phillyrea angustifolia L. and P. latifolia L. seeds in order to develop an optimized propagation protocol for Phillyrea species. Seeds of P. angustifolia and P. latifolia were collected from wild plants growing in Cáceres province (CW Spain) and Andalucía (S Spain), respectively. Percentage of water uptake for P. latifolia seeds was calculated. Seeds with and without endocarp were germinated at different constant and alternating temperatures. Seeds without endocarp were soaked in distilled water or gibberellic acid, and then set to germinate. Seeds with endocarp of both species were stratified at 5 ºC for 30 or 90 days and then the endocarp was completely removed from the seeds before they were sowed. Chemical scarification with sulfuric acid and mechanical scarification were tested on P. angustifolia seeds with endocarp. Phillyrea endocarp was permeable to water, since Phillyrea seeds with endocarp imbibed water, but water uptake was faster when the endocarp was removed. Moreover, the encodarp could interfere mechanically in the emergence of the radicle, since seed germination of Phillyrea species was promoted by the complete removal of the lignified endocarp surrounding each seed. Optimal germination temperature for both species was 15 ºC, and lower temperatures produced secondary dormancy. Soaking in distilled water or gibberellic acid did not significantly enhance seed germination. Cold stratification and chemical scarification treatments were detrimental for seed germination. Keywords cold stratification, Phillyrea species, treatments before sowing, seed germination, seed scarification, lignified endocarp.