Agrocampus Ouest

About: Agrocampus Ouest is a education organization based out in Rennes, France. It is known for research contribution in the topics: Population & Soil water. The organization has 2160 authors who have published 3219 publications receiving 75606 citations. The organization is also known as: Institut supérieur des sciences agronomiques, agroalimentaires, horticoles et du paysage & Higher Institute for agricultural sciences, food industry, horticulture and landscape management.

Indicators of earthworm bioturbation to improve visual assessment of soil structure

Abstract: Earthworm bioturbation, a biological process that strongly influences soil structure dynamics, is attracting more interest with the development of no-tillage farming. However, while methods for Visual Soil Structure Assessment (VSSA) are of great use to agronomists working to improve crop management and preserve soil structure, few methods have indicators that consider earthworm biostructures. One reason is that VSSA methods were initially created for conventional tillage systems, where tillage and compaction are the main drivers of soil structure over time, while bioturbation is a secondary driver. However, bioturbation is now recognised as an important process for soil functioning under no-tillage and reduced tillage systems. Among biostructures, the presence of burrows is one frequently-used indicator, but casts are rarely studied in the field, except in the “Soil-Structure Patterns” method (SSP), which provides a typology of soil structure that includes earthworm features. However the SSP typology appears complex (11 patterns), and implementing the method is time consuming. To improve VSSA methods, we identified patterns to define new indicators of earthworm bioturbation. We first assessed whether the patterns identified were useful for highlighting the real impact of bioturbation on the distribution of soil structures and the impact of tillage on earthworm activity. We then applied the pattern descriptions to the “profil cultural” method, which provides a detailed assessment of soil structure in the soil profile. This study was performed at two experimental sites in France experiencing different types of soil impacts (i.e. tillage, compaction). Identifying patterns in soil morphological units helped us to define four types of bioturbation: (1) type 0: no visible bioturbation; (2) type 1: presence of burrows; (3) type 2: presence of a few fresh cast aggregates; and (4) type 3: high presence of casts in different welded states. This new typology seemed relevant and complementary to typical indicators. When applied to the “profil cultural” method, these bioturbation indicators can improve the assessment of the soil structure usually provided by VSSA methods and provide more accurate information to agronomists and farmers about soil functioning, including biological activities.

Effect of biofuel co-products in pig diets on the excretory patterns of N and C and on the subsequent ammonia and methane emissions from pig effluent.

Abstract: This study was conducted to investigate the effects of incorporation into pig diets of 20% of different co-products from the biofuel industries, which are rich in fibre, on animal growth performance, on nitrogen (N) and carbon (C) excretions, and on the subsequent ammonia volatilisation and methane production during the storage of slurry. Five experimental diets mainly based on wheat and soyabean meal were formulated: two control diets, a control high-protein (CHP) diet with 17.5% of crude protein (CP) and a control low-protein (CLP) diet with 14.0% of CP and three experimental diets with 20% of (i) dried distiller’s grain with solubles (DDGS), (ii) sugar beet pulp (SBP) or (iii) fatty rapeseed meal (FRM). The animals used (20 castrated males) were housed individually in metabolism cages and fed one of the five diets (i.e. four pigs per diet). Urine and faeces were collected separately from each pig in order to measure nutrient digestibility and the excretory patterns of N and C. For each diet, ammonia volatilisation was measured from samples of slurry subsequently produced, over a 16-day storage period in a laboratory pilot scale system. The ultimate methane potential (B0, expressed in litres CH4/kg organic matter (OM)) was measured from the same slurry, for each diet, in anaerobic storage conditions over 100 days. The addition of sources of fibres to the diet decreased (P < 0.05) the animal growth performance by 13% and increased (P < 0.05) the amount of faeces excreted by 100%, whereas the amount of urine was not affected. For the high-fibre diets, there was a shift of N partitioning from urine to faeces, resulting in a much higher faecal N excretion (10 v. 5 g N/pig per day). Concurrently, the fibre enrichment in diets significantly increased (P < 0.05) the C content of the faeces by 68%. Ammonia emission from slurry was significantly reduced (P < 0.05) by 19% to 33% for the high-fibre diets, compared to the CHP diet. Ammonia emission was also reduced (P < 0.05) by 33% for the CLP compared to the CHP diet. B0 values ranged from 428 to 484 l CH4/kg OM. When these are expressed per pig and per day, the B0 from slurry was, on average, 70 l for the two control diets, and 121, 91 and 130 l for the slurry originating from the DDGS, SBP and FRM diets, respectively.

Camalexin contributes to the partial resistance of Arabidopsis thaliana to the biotrophic soilborne protist Plasmodiophora brassicae

Abstract: Camalexin has been reported to play defensive functions against several pathogens in Arabidopsis. In this study, we investigated the possible role of camalexin accumulation in two Arabidopsis genotypes with different levels of basal resistance to the compatible eH strain of the clubroot agent Plasmodiophora brassicae. Camalexin biosynthesis was induced in infected roots of both Col-0 (susceptible) and Bur-0 (partially resistant) accessions during the secondary phase of infection. However, the level of accumulation was four-to-seven times higher in Bur-0 than Col-0. This was associated with the enhanced transcription of a set of camalexin biosynthetic P450 genes in Bur-0: CYP71A13, CYP71A12, and CYP79B2. This induction correlated with slower P. brassicae growth in Bur-0 compared to Col-0, thus suggesting a relationship between the levels of camalexin biosynthesis and the different levels of resistance. Clubroot-triggered biosynthesis of camalexin may also participate in basal defense in Col-0, as gall symptoms and pathogen development were enhanced in the pad3 mutant (Col-0 genetic background), which is defective in camalexin biosynthesis. Clubroot and camalexin responses were then studied in Heterogeneous Inbred Families (HIF) lines derived from a cross between Bur-0 and Col-0. The Bur/Col allelic substitution in the region of the previously identified clubroot resistance QTL PbAt5.2 (Chromosome 5) was associated with both the enhanced clubroot-triggered induction of camalexin biosynthesis and the reduced P. brassicae development. Altogether, our results suggest that high levels of clubroot-triggered camalexin biosynthesis play a role in the quantitative control of partial resistance of Arabidopsis to clubroot.