Obtention de plantes dihaploïdes de rosier (Rosa x hybrida, cv « Sonia ») après parthénogenèse induite par l’emploi de pollen irradié et culture in vitro de graines immatures

International audience’Sonia’ var rose ovules produced plants through in vitro culture after being pollinated with irradiated (gamma rays) pollen. A 500-Gy minimum dose was sufficient to inactivate pollen and induce in situ parthenogenesis; in vitro culture was necessary for embryo rescue. The dihaploid plants originated from small embryos which occupied only a part of the carpel cavity; they were clearly distinguished from tetraploid plants by miniaturization of all organs. The dihaploid plants were observed under glass-house conditions until flowering presented a normal gynoecium. They produced a small amount of pollen of reduced but regular size; growth and development were faster than the tetraploid controls in summer.Des ovules de rosier, variété « Sonia », cultivés in vitro après pollinisation avec du pollen irradié aux rayons gamma ont évolué en plantes entières. Le pollen inactivé efficace pour induire une parthénogenèse in situ doit subir une dose minimale de 500 Gy et la culture in vitro paraît indispensable pour assurer la survie des embryons. Les plantes dihaploïdes proviennent de petits embryons n’occupant qu’une partie de la cavité carpellaire, elles se distinguent nettement des tétraploïdes par une miniaturisation de tous les organes. Les plantes dihaploïdes observées en serre jusqu’à leur floraison présentent un gynécée normal, elles ne produisent que très peu de pollen d’un diamètre réduit mais régulier. La croissance et le développement de ces plantes sont plus rapides en été que ceux de plantes tétraploïdes témoins

Dihaploid plants of roses (Rosa x hybrida, cv 'Sonia') obtained by parthenogenesis induced using irradiated pollen and in vitro culture of immature seeds

'Sonia' var rose ovules produced plants through in vitro culture after being pollinated with irradiated (gamma rays) pollen. A 500-Gy minimum dose was sufficient to inactivate pollen and induce in situ parthenogenesis; in vitro culture was necessary for embryo rescue. The dihaploid plants originated from small embryos which occupied only a part of the carpel cavity; they were clearly distinguished from tetraploid plants by miniaturization of all organs. The dihaploid plants were observed under glass-house conditions until flowering presented a normal gynoecium. They produced a small amount of pollen of reduced but regular size; growth and development were faster than the tetraploid controls in summer.Obtention de plantes dihaploïdes de rosier (Rosa x hybrida, cv « Sonia ») après parthénogenèse induite par l'emploi de pollen irradié et culture in vitro de graines immatures. Des ovules de rosier, variété « Sonia », cultivés in vitro après pollinisation avec du pollen irradié aux rayons gamma ont évolué en plantes entières. Le pollen inactivé efficace pour induire une parthénogenèse in situ doit subir une dose minimale de 500 Gy et la culture in vitro paraît indispensable pour assurer la survie des embryons. Les plantes dihaploïdes proviennent de petits embryons n'occupant qu'une partie de la cavité carpellaire, elles se distinguent nettement des tétraploïdes par une miniaturisation de tous les organes. Les plantes dihaploïdes observées en serre jusqu'à leur floraison présentent un gynécée normal, elles ne produisent que très peu de pollen d'un diamètre réduit mais régulier. La croissance et le développement de ces plantes sont plus rapides en été que ceux de plantes tétraploïdes témoins

Dihaploid plants of roses (Rosa x hybrida, cv Sonia) obtained by parthenogenesis induced using irradiated pollen and in vitro culture of immature seeds

’Sonia’ var rose ovules produced plants through in vitro culture after being pollinated with irradiated (gamma rays) pollen. A 500-Gy minimum dose was sufficient to inactivate pollen and induce in situ parthenogenesis; in vitro culture was necessary for embryo rescue. The dihaploid plants originated from small embryos which occupied only a part of the carpel cavity; they were clearly distinguished from tetraploid plants by miniaturization of all organs. The dihaploid plants were observed under glass-house conditions until flowering presented a normal gynoecium. They produced a small amount of pollen of reduced but regular size; growth and development were faster than the tetraploid controls in summer.Des ovules de rosier, variété « Sonia », cultivés in vitro après pollinisation avec du pollen irradié aux rayons gamma ont évolué en plantes entières. Le pollen inactivé efficace pour induire une parthénogenèse in situ doit subir une dose minimale de 500 Gy et la culture in vitro paraît indispensable pour assurer la survie des embryons. Les plantes dihaploïdes proviennent de petits embryons n’occupant qu’une partie de la cavité carpellaire, elles se distinguent nettement des tétraploïdes par une miniaturisation de tous les organes. Les plantes dihaploïdes observées en serre jusqu’à leur floraison présentent un gynécée normal, elles ne produisent que très peu de pollen d’un diamètre réduit mais régulier. La croissance et le développement de ces plantes sont plus rapides en été que ceux de plantes tétraploïdes témoins

New self-switching mechanisms for active bidirectional switches

The self-switching principle is a synthesis of synchronous type switching and switch inner protection mechanisms. Both switch ON and switch OFF are performed on the base of current and voltage measurement across the switch. Applied to an active bidirectional device, it may give complete autonomy to the switch. On the basis of those principles, the synthesis of an autonomous bidirectional free-wheeling path for an AC/AC buck converter is implemented with active switches. This paper introduces the current/ voltage state representation in order to illustrate the experimental switching mechanisms. As a further application, the automatic triac is synthesized for a bipolar AC/DC half-bridge converter

Étude du comportement de différents génotypes de rosiers de serre (Rosa hybrida) propagés par bouturage. I. Bouturage et culture de «miniplants» en serre.*

L'application d'une technique de bouturage rapide de rosiers de serre en conditions contrôlées d'environnement et avec des boutures calibrées, permet d'obtenir à toute époque de l'année des clones de «miniplants» en pots, cultivables ensuite en serres ou en chambres climatisées. La variation des caractéristiques morphologiques et physiologiques observées sur une collection variétale lors du bouturage et de la première floraison des miniplants en serre, et les relations existant entre caractéristiques des miniplants et d'une culture adulte sont présentées. Pour obtenir des lots homogènes de boutures puis de miniplants, il faut disposer en même temps d'un nombre suffisant de tiges florifères au même stade de maturité, ce qui limite l'emploi d'une telle technique dans un processus de sélection. Par contre, les observations et notations de caractéristiques importantes sont aisées. La culture de séries successives de miniplants permet, sur des espaces réduits, une approche relativement simple du développement des variétés de roses.Study of the behaviour of different genotypes of greenhouse rose trees (Rosa hybrida) propagated by cuttage. I. Cutting and growing of miniplants in greenhouses. A simple technique of cuttage of greenhouse roses allows year-round preparation of small "miniplant" clones for pot cultivation in greenhouses or climatic rooms (figs 1, 2). Some physiological traits of cuttings and miniplants can vary owing to their position on the mother stem (table I) and to environmental conditions during the cuttage period (table II). In order to reduce the causes of variation, cuttage was carried out in a controlled environment, with standardized size and node level cuttings. Morphological and physiological traits observed in an assortment of genotypes during rooting (table III), and the miniplant crop period in the greenhouse (table IV, V), and the relations between data collected on miniplants and on an adult crop (table VI) are presented. In order to obtain homogeneous batches of cuttings and subsequently of miniplants, a sufficient number of floral stems at the same stage of maturity and available at the same time is required. This prerequisite constitutes a limitation of the technique as a tool in breeding processes. On the other hand, observation and determination of important characteristics do not present problems. With successive crops of miniplants on limited cultivation surfaces it is possible to study in a simple manner the development of rose varieties

SUPERCAPACITORS FOR PEAK-POWER DEMAND IN FUEL-CELL-DRIVEN CARS

A downscaled drive train with a 6.5 kW fuel cell and a 10 kW supercapacitor module was realized and tested. The voltage levels and the energy flow between fuel cell and supercapacitor were controlled by an electronic unit. The combined fuel-cell/supercapacitor drive train was tested with a modified New European Driving Cycle (NEDC). The 60 V, 60 F supercapacitor module consisted of 2 x 24 capacitors in series having a capacitance of 800 F each. The capacitors had a max. specific energy of 2.75 Wh/kg and a max. specific power of 6.5 kW/kg. An active electronic unit managed voltage balancing among the 24 capacitors in series. The capacitor module had a max. total energy of 30 Wh and a total max. power of 45 kW and could deliver 10 kW over a period of 6 seconds. It was demonstrated that a supercapacitor is an energy storage device that can be used efficiently in vehicle applications for recuperating braking energy and boosting peak power

Hy.Power—A technology platform combining a fuel cell system and a supercapacitor

In the attempts to attain greater efficiency of mobility, based in the long-term on renewable energy sources, the efficiency of energy conversion in the vehicle remains an important issue. Polymer electrolyte membrane fuel cell technology has the potential to improve the efficiency of the powertrain for passenger vehicles above the level of present internal combustion engine solutions in relevant operation areas. Several questions need still to be solved to verify this potential superiority under the conditions of daily vehicle operation. Therefore, new materials have to be developed for improved component performance at lower cost and for more complicated environmental conditions. The effect of these specifications on the efficiency potential of the fuel cell system is open to debate. Another target is the performance of advanced powertrains based on internal combustion engines, which are in competition with the fuel cell system