Jonas Aper

Absorption, translocation and metabolism of metamitron in Chenopodium album

BACKGROUND In recent years, common lambsquarters (Chenopodium album L.) populations from sugar beet fields in different European countries have responded as resistant to the as-triazinone metamitron. The populations have been found to have the same D1 point mutation as known for atrazine-resistant biotypes (Ser264 to Gly). However, pot experiments revealed that metamitron resistance is not as clear-cut as observed with triazine resistance in the past. The objectives of this study were to clarify the absorption, translocation and metabolic fate of metamitron in C. album. RESULTS Root absorption and foliar absorption experiments showed minor differences in absorption, translocation and metabolism of metamitron between the susceptible and resistant C. album populations. A rapid metabolism in the C. album populations was observed when metamitron was absorbed by the roots. The primary products of metamitron metabolism were identified as deamino-metamitron and metamitron-N-glucoside. PABA, known to inhibit the deamination of metribuzin, did not alter the metabolism of metamitron, and nor did the cytochrome P450 inhibitor PBO. However, inhibition of metamitron metabolism in the presence of the cytochrome P450 inhibitor ABT was demonstrated. CONCLUSION Metamitron metabolism in C. album may act as a basic tolerance mechanism, which can be important in circumstances favouring this degradation pathway.

What Global and/or European Agriculture Will Need from Grasslands and Grassland Breeding over the Next 10–15 Years for a Sustainable Agriculture

The paper analyses actual trends in (European) ruminant agriculture and grassland based production systems. Consequences of reduced and/or zero grazing for grass breeding and grassland management are discussed. The impacts on eco-efficiency, recycling of minerals and ecosystem services are highlighted as well as the role of ley-arable farming. Special emphasis is on the potential use of tall fescue as a component of mixtures or as an interspecific cross. In grazed grassland, the role of white clover, the disease resistance and the nitrogen use efficiency of the grasses and the significance of biodiversity are considered. Based on an article published by Parsons et al. (2011) some reflections on the way ahead in grass and forage breeding are presented.

Drought Stress-Induced Changes in Gas Exchange, Chl a Fluorescence Parameters and Yield in Lolium, Festuca and Festulolium

Changes in yield and physiological processes in drought stress (40 % field water capacity) and well-watered conditions (70 % field water capacity) in forage grasses were investigated. Nine varieties from five species (Lolium perenne, Lolium multiflorum, Festuca pratensis, Festuca arundinacea and Festulolium braunii) were examined in a pot experiment in a greenhouse in 2013–2014 in Poland. The aim of the study was to assess the effects of water deficit on different forage grasses. All measured physiological parameters were affected by drought stress in the different cuts. Intensity of photosynthesis, transpiration rate and dry matter yield were significantly lower in drought stress than under well-watered conditions in all varieties. The differences in chlorophyll fluorescence (the Fv/Fm ratio, an estimation of the PSII phytochemical efficiency) were less pronounced, although most of varieties showed a minor but significant decrease of the Fv/Fm ratio under drought stress.

Report of the Breeding Debate

Based on a questionnaire with 11 questions, 5 breeding institutes and 4 breeding companies defined their 2035 horizon for grass and forage crops breeding. Visions and opinions differed a lot regarding targeted species, breeding goals, importance of plant physiology, breeding techniques, testing environments, the use of molecular tools and the influence of regulations and sustainability drivers. The report can be considered as a joint reference document for future debates.