Wheat lines exhibiting variation in tolerance of Septoria tritici blotch differentiated by grain source limitation

Septoria tritici blotch (STB) is the most damaging disease of wheat crops in Europe. Because of the partial nature of genotypic resistance or the increasing resistance against fungicides, the tolerance, i.e. maintaining yield in the presence of expressed disease, is a relevant alternative. Tolerance is generally estimated through the yield loss per unit of source reduction, contrasts of tolerance between genotypes have been observed previously suggesting that either increasing the source availability or improving the use of stored assimilate could improve tolerance. This paper aims at developing a source/sink approach to understand the tolerance mechanism and identifying potential traits to increase tolerance of STB. A field experiment was designed to explore the relation between tolerance of STB and source/sink balance. Based on six wheat genotypes contrasting for tolerance exposed to natural STB epidemics, late nitrogen fertilization and a 50% spikelet removal were applied to change the source/sink balance. The tolerance of genotypes was quantitatively estimated over three additional field experiments. We found that STB tolerance was correlated with traits of healthy crops (high individual grain weight and high green leaf lamina area as the proportion of leaf 3). The spikelet removal revealed a highly variable degree of source limitation for grain filling amongst the six genotypes. Thus, we proposed an easily calculated index that highly correlated positively with the labor intensive estimation of STB tolerance. Finally, potential yield and tolerance were not correlated, which suggests that breeding for yield performance and tolerance could be possible

New SHRIMP U-Pb zircon ages from the Hartswater group, South Africa: Implications for correlations of the Neoarchean Ventersdorp Supergroup on the Kaapvaal craton and with the Fortescue Group on the Pilbara craton

The Neoarchean Hartswater Group of the western Kaapvaal craton is a bimodal volcanic and sedimentary cratonic cover succession traditionally correlated with the Platberg Group of the ~2.71. Ga Ventersdorp Supergroup, South Africa. Correlation between exposures of the Platberg Group equivalents across the Kaapvaal craton is complicated, because they were deposited within isolated grabens, they display lateral facies changes over short distances, and they are extensively covered by calcrete and sand. Such correlation is important, since these units constitute one of the oldest unconformity-bounded sequences originally compared with sequences from the Pilbara craton (northwestern Australia) for reconstructing the ancient continent " Vaalbara" . Present age constraints, however, imply a ~50 million year discrepancy in the shared geological histories of the cratons. Here we report SHRIMP U-Pb zircon ages from a prominent pyroclastic surge and ash fall deposit in the lower Hartswater Group (2733.4. ±. 3.4. Ma) and from variable quartz-feldspar porphyry in the upper Hartswater Group (2724.3. ±. 5.8. Ma). The new constraints significantly improve correlations of the Platberg Group equivalents on the western Kaapvaal craton, and present a clear solution to the apparent enigma in cross-craton correlation. The data cast doubt on the 2714. Ma age for the Klipriviersberg Group of the east central Kaapvaal craton, and strengthen lithostratigraphic correlations with units from the Pilbara craton (i.e., the Hardey Sandstone, the Bamboo Creek and Spinaway porphyries, the Kylena Basalt, and in part the Tumbiana Formation). When our ages are placed within paleogeographic context a systematic picture of a shared long-lived extensional event emerges

Stratigraphy, depositional setting, and shrimp u-pb geochronology of the banded iron formation–bearing bailadila group in the bacheli iron ore mining district, bastar craton, india

The Bailadila Group of the Bastar Craton, India, is host to a 200-m-thick banded iron formation (BIF). We document the lithostratigraphic context for the BIF, informally referred to as the Bose iron formation, and provide radiometric constraints for its depositional age. Field evidence illustrates that the BIF was deposited on an inner-shelf succession with a quartz arenite that grades upward into the BIF through storm-dominated offshore shelf deposits. The quartz arenite to BIF transition records a relative sea level rise from transgressive to highstand systems tract when the BIFs were deposited in a starved outer continental shelf. U-Pb SHRIMP analyses of zircons from the basement of the Bailadila Group yielded mostly highly discordant U-Pb SHRIMP ages. However, the ages fall on well-defined discordia lines from which concordia intercept ages could be determined. These ages, in combination with the ages of a few zircons that are less than 6% discordant, indicate that the granitoid basement crystallized at 3500–3550 Ma. The maximum depositional age of the Bailadila Group is constrained from the weighted mean Pb/ Pb SHRIMP age of 2725 5 57 Ma from detrital zircons from the basal arenites. A well-constrained weighted mean Pb/ Pb SHRIMP age of 2733 5 53 Ma for zircons from a unit that unconformably overlies the Bailadila Group is within error of that age. Stratigraphic relationships suggest that the Bailadila succession is unconformably overlain by the ~2.5 Ga Kotri and Dongargarh Supergroups. The depositional age of the Bailadila Group is well constrained between ~2.7 and 2.5 Ga. In contrast to most other Archean Algoma-type iron formations of peninsular India, which are closely related to volcanic rocks in greenstone belts, the Bose iron formation is associated with siliciclastic shelf succession. It thus is considered a Superior-type iron formation that represents the oldest known one of its kind in India.This work is an outcome of a collaborative researchproject funded by the Department of Science andTechnology (DST) in India and the Department ofScience and Innovation (DSI), as well as the Na-tional Research Foundation (NRF) in South Africa

Differentiell lobformning för tvådimensionella antennuppställningar i ett LTE-FDD-system

Basstationer med flera antenner kan aktivt styra signalenergi mot en mottagare med hjälp av lobformning, vilket ger högre datatakt och lägre strömförbrukning än med en enda antenn. Lobformning kräver dock att kanalen skattas till varje antenn och i ett FDD-system måste denna skattning återkopplas till basstationen från mottagaren, vilket innebär en opraktiskt stor overhead, speciellt när loberna blir smalare. Differentiell lobformning är en robust teknik som med begränsad overhead möjliggör smala och välriktade lober genom differentiella justeringar av lobformen. Med hjälp av två förkodade referenssignaler från basstationen skattar mottagaren kanalen och rapporterar iterativt hur lobformningen ska förbättras så att SINR hos den mottagna signalen ökar. Den här uppsatsen utvecklar en algoritm som utökar differentiell lobformning till användandet av tvådimensionella antennuppställningar, vilket möjliggör justering av lobformen i två dimensioner och därmed potentiellt sett ökar mottagen signalstyrka. Algoritmen alternerar mellan att differentiellt justera lobformen horisontellt och vertikalt, utan ökad overhead. Algoritmen har testats för olika antennuppställningar i ett stadsscenario och ett landsbygdsscenario med horisontell användarfördelning, vilken dock har visat sig vara en begränsande faktor för att påvisa de potentiella vinster som differentiell lobformning i två dimensioner för med sig. Resultatet visar att det är viktigare att kunna erhålla en smal lob i den dimension där det finns många användare, i detta fall den horisontella dimensionen, än i den ortogonala dimensionen.Base stations with multiple antenna elements can actively direct signal energy towards a user by means of beam-forming, which results in higher data rates and lower energy consumption compared to a single antenna element. However, beam-forming requires channel state estimates to each antenna element and in an FDD system, these estimates must be fed back to the base station from the user. This feedback infer an inconvenient amount of overhead, especially as the beam gets narrow. Differential beam-forming is a robust technique that, through differential adjustments to the beam shape, allows for narrow and well-directed beams at a low overhead cost. By means of two precoded reference signals from the base station, the user estimates the channel and iteratively reports how the beam-forming should be improved in order to increase the SINR of the sent signal. This thesis develops an algorithm that extends differential beam-forming to the usage of two-dimensional antenna arrays, which allows for adjustments of the beam in two dimensions. Thereby, the received signal strength is potentially increased. The algorithm alternates between differential adjustments to the beam horizontally and vertically, without increased overhead. The algorithm is simulated with different array sizes using an urban and a rural scenario with a horizontal user distribution. However, the biased user distribution has proven to constitute a limiting factor in order to demonstrate the potential benefits of differential beam-forming in two dimensions. The result shows that it is more important to obtain a narrow beam in the dimension where many users are located, in this case the horizontal dimension, than in the orthogonal dimension