Effects of water management and cultivar on carbon dynamics, plant productivity and biomass allocation in European rice systems

Water saving techniques, such as alternate wetting and drying (AWD), are becoming a necessity in modern rice farming because of climate changemitigation and growing water use scarcity. Reducing water can vastly reduce methane (CH4) emissions; however, this net climate benefit may be offset by enhanced carbon dioxide (CO2) emissions from soil. The main aims of this study were: to determine the effects of AWD on yield and ecosystem C dynamics, and to establish the underlyingmechanistic basis for observed trends in net ecosystem C gain or loss in an Italian rice paddy. We investigated the effects of conventional water management (i.e. conventionally flooded paddy; CF) and AWD on biomass accumulation (aboveground, belowground, grain), key ecosystem C fluxes (net ecosystem exchange (NEE), net primary productivity (NPP), gross primary productivity (GPP), ecosystem respiration (ER), autotrophic respiration (RA), heterotrophic respiration (RH)), and soil organic matter (SOM) decay for four common commercial European rice cultivars. The most significant finding was that neither treatment nor cultivar affected NEE, GPP, ER or SOM decomposition. RA was the dominant contributor to ER for both CF and AWD treatments. Cultivar and treatment affected the total biomass of the rice plants; specifically, with greater root production in CF compared to AWD. Importantly, therewas no effect of treatment on the overallyield for any cultivar. Possibly, the wetting-drying cycles may have been insufficient to allow substantial soil C metabolism or there was a lack of labile substrate in the soil. These results imply that AWD systems may not be at risk of enhancing soil C loss,making it a viable solution for climate change mitigation and water conservation. Althoughmore studies are needed, the initial outlook for AWDin Europe is positive;with no net loss of soil C from SOM decomposition, whilst also maintaining yield

Effects of the application of a moderate alternate wetting and drying technique on the performance of different European varieties in Northern Italy rice system

Alternate wetting and drying (AWD) technique has been developed and evaluated on rice (Oryza sativa) systems in several countries worldwide for increasing water use efficiency and reducing negative effects of permanent flooding, like the increase in methane emissions and arsenic availability in soil. In this study, a paddy field experiment was carried out for two years to evaluate the application in Northern Italy rice area of a moderate AWD, i.e. only implemented during the vegetative phase of the crop and ponded water maintained thereafter, compared with Continuous Flooding (CF) system. The adaptability of 12 European commercial rice cultivars to AWD was investigated in terms of crop phenology, morphological traits, root production, nitrogen (N) uptake, yield, milled rice yield and microelement concentration in grains. Results showed substantial (40.7 %) water saving probably favoured by the presence of a shallow water table. In these pedoclimatic conditions, very limited effects of a mild AWD on crop status and final productivity were recorded and the commercial cultivars did not display significant different adaptabilities to the water stress. Moreover, AWD decreased arsenic (As) concentration in grain but increased grain Cadmium (Cd) being the degree of such a response dependent upon the variety, suggesting that the genotype plays an important role in this aspect of adaptation to AWD

Plasma jet experiments using LULI 2000 laser facility

International audienceWe present experiments performed with the LULI2000 nanosecond laser facility. We generated plasma jets by using specific designed target. The main measured quantities related to the jet such as its propagation velocity, temperature and emissive radius evolution are presented. We also performed analytical work, which explains the jet evolution in some cases

Supersonic-jet experiments using a high-energy laser

International audienceIn this Letter, laboratory astrophysical jet experiments performed with the LULI2000 laser facility are presented. High speed plasma jets (150km·s-1) are generated using foam-filled cone targets. Accurate experimental characterization of the plasma jet is performed by measuring its time evolution and exploring various target parameters. Key jet parameters such as propagation and radial velocities, temperature, and density are obtained. For the first time, the required dimensionless quantities are experimentally determined on a single-shot basis. Although the jets evolve in vacuum, most of the scaling parameters are relevant to astrophysical conditions

Supersonic-jet experiments using a high-energy laser

In this Letter, laboratory astrophysical jet experiments performed with the LULI2000 laser facility are presented. High speed plasma jets (150 km.s(-1)) are generated using foam-filled cone targets. Accurate experimental characterization of the plasma jet is performed by measuring its time evolution and exploring various target parameters. Key jet parameters such as propagation and radial velocities, temperature, and density are obtained. For the first time, the required dimensionless quantities are experimentally determined on a single-shot basis. Although the jets evolve in vacuum, most of the scaling parameters are relevant to astrophysical conditions.</p

Radiative Shocks And Plasma Jets As Laboratory Astrophysics Experiments

International audienceDedicated laboratory astrophysics experiments have been developed at LULI in the last few years. First, a high velocity (70 km/s) radiative shock has been generated in a xenon filled gas cell. We observed a clear radiative precursor, measure the shock temperature time evolution in the xenon. Results show the importance of 2D radiative losses. Second, we developed specific targets designs in order to generate high Mach number plasma jets. The two schemes tested are presented and discussed

Radiative Shocks And Plasma Jets As Laboratory Astrophysics Experiments

International audienceDedicated laboratory astrophysics experiments have been developed at LULI in the last few years. First, a high velocity (70 km/s) radiative shock has been generated in a xenon filled gas cell. We observed a clear radiative precursor, measure the shock temperature time evolution in the xenon. Results show the importance of 2D radiative losses. Second, we developed specific targets designs in order to generate high Mach number plasma jets. The two schemes tested are presented and discussed