Österreichisches Projekt Grundlagen zur Züchtung, Vermehrung und Sorten-/Saatgutprüfung für den Biolandbau: Ergebnisübersicht

In the Austrian research project “Basic principles for breeding, multiplication and variety testing for organic agriculture” (from 2004 until 2008) novel methods for the assessment of the suitability of seed and cultivars for organic farming were developed and evaluated by an interdisciplinary co-operation of researchers, breeders and variety testers. Organic farming requires specific combinations of crop plant characters, especially seed health and resistance against seed-borne diseases. Another crucial feature is the competitive ability against weeds. Early development was found to significantly increase the competitiveness of different crop plants. Genotypic variation in characters necessary for an efficient utilisation of below-ground resources was also investigated, e.g. interrelations between root development and drought stress tolerance and between mycorrhiza formation and nutrient use efficiency. Based on the results obtained in various cultivar trials, it can be concluded that genotypes suitable for organic growing conditions may be pre-selected from early breeding material of conventional breeding programmes. The selected breeding material must subsequently be rigorously tested on organically managed fields starting from the first yield trials at the latest. The project results were communicated to farmers and advisors during field days and excursions. They will be applied in the breeding of new cultivars

Activation of Methanogenesis in Arid Biological Soil Crusts Despite the Presence of Oxygen

Methanogenesis is traditionally thought to occur only in highly reduced, anoxic environments. Wetland and rice field soils are well known sources for atmospheric methane, while aerated soils are considered sinks. Although methanogens have been detected in low numbers in some aerated, and even in desert soils, it remains unclear whether they are active under natural oxic conditions, such as in biological soil crusts (BSCs) of arid regions. To answer this question we carried out a factorial experiment using microcosms under simulated natural conditions. The BSC on top of an arid soil was incubated under moist conditions in all possible combinations of flooding and drainage, light and dark, air and nitrogen headspace. In the light, oxygen was produced by photosynthesis. Methane production was detected in all microcosms, but rates were much lower when oxygen was present. In addition, the δ13C of the methane differed between the oxic/oxygenic and anoxic microcosms. While under anoxic conditions methane was mainly produced from acetate, it was almost entirely produced from H2/CO2 under oxic/oxygenic conditions. Only two genera of methanogens were identified in the BSC-Methanosarcina and Methanocella; their abundance and activity in transcribing the mcrA gene (coding for methyl-CoM reductase) was higher under anoxic than oxic/oxygenic conditions, respectively. Both methanogens also actively transcribed the oxygen detoxifying gene catalase. Since methanotrophs were not detectable in the BSC, all the methane produced was released into the atmosphere. Our findings point to a formerly unknown participation of desert soils in the global methane cycle

Gerste und Rizinus in Papyri aus Princeton

Auf allen Seiten vollständiger Papyrus; unten ein ca. 2,5 cm breiter Freiraum, zwei senkrechte Falten, am linken Rand eine Kollesis. Schrift parallel zu den Fasern, schwarze Tinte. Die Versoseite ist unbeschrieben

Ein neuer Zeuge der "Vatermördergeschichte"

Pergament, Kodexblatt, das oben und rechts noch zum Teil den ursprünglichen Randerhalten hat, sonst abgebrochen, löchrig und verzogen ist. Der Text wurde von J. Diethart als neuer Beleg der "Vatermördergeschichte" identifiziert, die durch die Editionen von H. Harrauer und P. J. Sijpesteijn in MPER XV 117-132 (vgl. dazu auch J. Kramer, ZPE 63 [1986] 246 ff.) bekannt geworden ist, [...

Bemerkungen zu Papyri III

Bemerkungen zu Papyri III <Korr. Tyche 28-34&gt

Bemerkungen zu Papyri VII ( 130-147)

Bemerkungen zu Papyri VII (<Korr. Tyche> 130-147

Bemerkungen zu Papyri VI ( 76-119)

Bemerkungen zu Papyri VI (<Korr. Tyche> 76-119

Bemerkungen zu Papyri VIII ( 148-205)

Bemerkungen zu Papyri VIII (<Korr. Tyche> 148-205