The effect of maize silage type on the performances and methane emission of dairy cattle.

To examine whether type of maize silage is important for milk production performances, maize silage LG30224 (LG) was compared with Falkone (FA), the latter having a 4.0% points lower rumen NDF digestibility and 19 g/kg dry matter (DM) more starch. To bridge the lower energy content of FA, a third treatment was involved by adding maize meal (MM) in a ratio of 92/8 on DM (FA+MM). Maize and grass silage were fed ad libitum in a ratio of 65/35 on DM basis. Concentrates were supplemented individually to meet energy and protein requirements. The experiment was set up as a Latin square with three groups of nine Holstein cows during three periods of 3 weeks. In the last 2 weeks of each period, DM intake (DMI) and milk performances were measured. Each group included one cannulated cow to study effects on rumen fermentation. During the last 4 days of each period, two cows from each group were placed in gas exchange chambers to measure nutrient digestibility and methane production. Total DMI was higher (p < 0.05) for FA+MM (20.8 kg/day) than for FA (20.3 kg/day), while DMI for LG was intermediate (20.6 kg/day). Treatment did not affect milk production nor composition, whereas fat-protein-corrected milk was higher for LG (30.5 kg/day) and FA+MM (30.3 kg/day) than for FA (29.9 kg/day). The ration did not affect pH nor volatile fatty acid composition in the rumen. Further, total tract digestibility of OM, crude protein, NDF and starch did not differ among treatments. The ration with LG gave higher methane production per day and per kg NDF intake than both rations with FA, but the difference was not significant when expressed per kg DMI or FPCM. Thus, maize silage type is of little importance for milk production if energy and physical structure requirements are met.

HERBICIDE SENSITIVITY OF ECHINOCHLOA CRUS-GALLI POPULATIONS: A COMPARISON BETWEEN CROPPING SYSTEMS.

Echinochloa crus-galli populations exhibit high morphological variability and their response to herbicides varies from field to field. Differential response to herbicides could reflect differences in selection pressure, caused by years of cropping system related herbicide usage. This study investigates the relation between herbicide sensitivity of Echinochloa crus-galli populations and the cropping system to which they were subjected. The herbicide sensitivity of Echinochloa crus-galli was evaluated for populations collected on 18 fields, representing three cropping systems, namely (1) a long-term organic cropping system, (2) a conventional cropping system with corn in crop rotation or (3) a conventional cropping system with long-term monoculture of corn. Each cropping system was represented by 6 E. crus-galli populations. All fields were located on sandy soils. Dose-response pot experiments were conducted in the greenhouse to assess the effectiveness of three foliar-applied corn herbicides: nicosulfuron (ALS-inhibitor), cycloxydim (ACCase-inhibitor) and topramezone (HPPD-inhibitor), and two soil-applied corn herbicides: S-metolachlor and dimethenamid-P (both VLCFA-inhibitors). Foliar-applied herbicides were tested at a quarter, half and full recommended doses. Soil-applied herbicides were tested within a dose range of 0-22.5 g a.i. ha(-1) for S-metolachlor and 0-45 g a.i. ha(-1) for dimethenamid-P. Foliar-applied herbicides were applied at the three true leaves stage. Soil-applied herbicides were treated immediately after sowing the radicle-emerged seeds. All experiments were performed twice. The foliage dry weight per pot was determined four weeks after treatment. Plant responses to herbicides were expressed as biomass reduction (%, relative to the untreated control). Sensitivity to foliar-applied herbicides varied among cropping systems. Compared to populations from monoculture corn fields, populations originating from organic fields were significantly more sensitive to cycloxydim, topramezone and nicosulfuron (resp. 5.3%, 5.9% and 12.3%). Populations from the conventional crop rotation system showed intermediate sensitivity levels. Contrary to foliar-applied herbicides, the effectiveness of soil-applied herbicides was not affected by cropping system. Integrated weed management may be necessary to preserve herbicide efficacy on the long term.

MOLECULAR INSIGHTS ON THE FUNCTIONAL MICROBIAL COMMUNITY FROM ORGANIC AND MINERAL GROWING MEDIA AND ITS INTERACTION WITH AGROBACTERIUM RHIZOGENES.

Despite numerous preventative measures, the hairy roots syndrome is an increasing problem in greenhouse horticulture. A recent survey of 177 tomato, cucumber and eggplant growers in Flanders (Belgium) revealed an increase of this disease in the last two years, with about 26% of all the tomato crops showing the syndrome. In this study, we compared the physicochemical and microbial community characteristics of inorganic and organic growing media in relation to the presence of the causative agent of the hairy roots, the plant pathogen Agrobacterium rhizogenes. We aimed to identify how the microbial and environmental interactions influenced the development and spread of this disease in a soilless cultivation system. Multivariate statistical analysis performed to assess the characteristics of each growing media revealed key variables impacting the hosted microbial community. Thus, humidity, pH, potassium and conductivity were drivers of the differences among microbial community composition. High throughput sequencing analysis of the bacterial family abundance of the communities present in organic media indicated potential competitive interactions with A. rhizogenes. Based on our hypothesis that growing media hosted a particular microbiota with potential for modulating hairy roots, we determined how the environment in organic media is reshaped to avoid establishment of A. rhizogenes. Our methodology provides a comprehensive insight into the complex bacterial interactions in horticultural media, which may be potentially applied for the development of effective control strategies and decrease in economic losses.

Seed germination, seedling emergence, seed persistence and triflusulfuron-methyl sensitivity in Galinsoga parviflora and G. quadriradiata.

Galinsoga quadriradiota Ruiz and Pavon (hairy galinsoga) and Galinsogo parviflora Cav. (smaliflower galinsoga, gallant soldier) are very troublesome weeds in many vegetable row crops in Europe. In order to optimize further management strategies for Galinsoga control in-depth study of germination biology was performed. Germination experiments were conducted to evaluate the impact of light and alternating temperatures on germination of a large set of Galinsoga populations. Seedling emergence was investigated by burying seeds at different depths in a sand and sandy loam soil. Dormancy of fresh achenes harvested in autumn was evaluated by studying germination response in light at 25/20 degrees C with and without nitrate addition. Seed longevity was investigated in an accelerated ageing experiment by exposing seeds to 45 degrees C and 100% relative humidity. A dose-response pot experiment was conducted in the greenhouse to evaluate the effectiveness of triflusulfuron-methyl, applied at the one leaf pair stage, for controlling Belgian Galinsoga populations. Galinsoga seeds required light for germination; light dependency varied among populations. Seedling emergence decreased drastically with increasing burial depth. Maximum depth of emergence varied between 4 and 10mm depending on soil type and population. In a sandy soil, emergence percentages were higher and seedlings were able to emerge from greater depths than in a sandy loam soil. Freshly produced G. parviflora seeds showed a varying but high degree of primary dormancy and were less persistent than G. quadriradiata seeds which lack primary dormancy. Galinsoga parviflora populations were more sensitive to triflusulfuron-methyl than G. quadriradiata populations. The lack of primary dormancy, high seed persistence and lower herbicide sensitivity may explain the higher distribution and abundance of G. quadriradiata over G. parviflora populations in Belgium. Overall, features such as lack of primary dormancy of freshly harvested G. quadriradiata seeds and light dependency for germination may be used to optimize and develop Galinsoga management strategies.

The origin of metamitron resistant Chenopodium album populations in sugar beet.

Chenopodium album L. is a major weed in spring-planted crops in the temperate regions of the world. Since 2000, farmers have reported an unsatisfactory control of this weed in sugar beet fields in Belgium, France and The Netherlands. Frequently, the surviving C. album plants are resistant to metamitron, a key herbicide in this crop. Metamitron resistance in C. album is caused by a Ser264 to Gly mutation in the psbA gene on the chloroplast genome, which prevents binding of metamitron to its target site. This mutation causes also resistance to other herbicides with a similar mode of action, like metribuzin -applied in potato- and atrazine in particular. Atrazine has been applied very frequently in maize in the 1970s and the 1980s, but is now banned in Europe due to environmental reasons. The persistent use of atrazine in maize confronted Belgian and other European farmers in the early 1980s with atrazine resistant C. album with the same Ser264 to Gly mutation. The problems with atrazine resistant C. album disappeared when other herbicides were applied in maize. Unfortunately, this is not the case for metamitron resistant C. album in sugar beet, because no replacement herbicide is readily available. The history of atrazine use in maize brought up a question concerning the origin of the current metamitron resistant C. album populations. Have these populations been selected locally by regular use of metamitron in sugar beet or did the selection occur earlier by atrazine use when maize was grown in the same fields? This would have serious implications regarding the reversibility of herbicide resistance. Therefore, soil samples were collected on 16 fields with different histories: five fields with an organic management over 25 years, two fields with a history of atrazine resistant C. album, five fields with metamitron resistant C. album in sugar beet and four fields which were under permanent grassland for 10 years, preceded by a regular rotation in which sugar beet was a key crop. The seeds of C. album were extracted from the soil and germinated on a germination table. Germinated seeds were allowed to grow in a growth chamber. Metamitron resistance was determined by a chlorophyll fluorescence test and leaf material was sampled for AFLP-analysis. For all fields, estimations were made of the size of the seed bank (i.e. an indirect estimate of population size), the frequency of resistant plants and the genetic diversity of resistant and susceptible populations. The results indicate that herbicide-resistant C. album populations are persistent and maintain their adaptive capacity, challenging future management of metamitron resistant C. album.

Sensitivity of locally naturalized Panicum species to HPPD- and ALS-inhibiting herbicides in maize.

Until recently the Panicum species Panicum schinzii Hack. (Transvaal millet), Panicum dichotomiflorum Michx. (Fall panicum) and Panicum capillare L. (Witchgrass) were completely overlooked in Belgium. Since 1970, these species have gradually spread and are now locally naturalized and abundant in and along maize fields. One of the possible raisons for their expansion in maize fields might be a lower sensitivity to postemergence herbicides acting against panicoid grasses, in particular those inhibiting 4-hydroxyphenyl pyruvate dioxygenase (HPPD) and acetolactate synthase (ALS). A dose-response pot experiment was conducted in the greenhouse to evaluate the effectiveness of five HPPD-inhibiting herbicides (sulcotrione, mesotrione, isoxaflutole, topramezone, tembotrione) and two ALS-inhibiting herbicides (nicosulfuron, foramsulfuron) for controlling Belgian populations of P. schinzii, P. dichotomiflorum and P. capillare. Shortly after sowing, half of all pots were covered with a film of activated charcoal to evaluate foliar activity of the applied herbicides. In another dose-response pot experiment, sensitivity of five local P. dichotomiflorum populations to HPPD-inhibitors and nicosulfuron was investigated. Finally, the influence of leaf stage at time of herbicide application on efficacy of topramezone and nicosulfuron for Panicum control was evaluated. Large interspecific differences in sensitivity to HPPD-inhibiting herbicides were observed. Panicum schinzii was sensitive (i.e., required a dose lower than the maximum authorized field dose to achieve 90% reduction in biomass) to tembotrione but moderately sensitive (i.e. required maximum field dose) to topramezone and poorly sensitive (i.e. required three-fold higher dose than maximum field dose) to mesotrione and sulcotrione. However, P. dichotomiflorum, a species that morphologically closely resembles P. schinzii, was sensitive to mesotrione and topramezone but moderately sensitive to tembotrione. All Panicum species were sensitive to low doses of nicosulfuron and foramsulfuron. The relative contribution from soil activity to weed control resulting from postemergence applications was important for isoxaflutole, sulcotrione, tembotrione and mesotrione but not for topramezone, nicosulfuron and foramsulfuron. Naturalized Panicum dichotomiflorum populations exhibited differential herbicide sensitivity profiles. Panicum schinzii, P. capillare and P.dichotomiflorum showed a progressive decrease in sensitivity to topramezone and nicosulfuron during seedling development. A satisfactory postemergence control of Panicum species in the field will require appropriate choice of herbicide and dose, as well as a more timely application (i.e. before weeds reach the four leaves stage).

Local spread of metamitron resistant Chenopodium album L. patches.

Molecular markers can provide valuable information on the spread of resistant weed biotypes. In particular, tracing local spread of resistant weed patches will give details on the importance of seed migration with machinery, manure, wind or birds. This study investigated the local spread of metamitron resistant Chenopodium album L. patches in the southwest region of the province West-Flanders (Belgium). During the summer of 2009, leaf and seed samples were harvested in 27 patches, distributed over 10 sugar beet fields and 1 maize field. The fields were grouped in four local clusters. Each cluster corresponded with the farmer who cultivated these fields. A cleaved amplified polymorphic sequence (CAPS) procedure identified the Ser264 to Gly mutation in the D1 protein, endowing resistance to metamitron, a key herbicide applied in sugar beet. The majority of the sampled plants within a patch (97% on average) carried this mutation. Amplified fragment length polymorphism (AFLP) analysis was performed with 4 primer pairs and yielded 270 molecular markers, polymorphic for the whole dataset (303 samples). Analysis of molecular variance revealed that a significant part of the genetic variability was attributed to variation among the four farmer locations (12 %) and variation among Chenopodium album patches within the farmer locations (14%). In addition, Mantel tests revealed a positive correlation between genetic distances (linearised phipt between pairs of patches) and geographic distances (Mantel-coefficient significant at p = 0.002), suggesting isolation-by-distance. In one field, a decreased genetic diversity and strong genetic relationships between all the patches in this field supported the hypothesis of a recent introduction of resistant biotypes. Furthermore, genetic similarity between patches from different fields from the same farmer and from different farmers indicated that seed transport between neighbouring fields is likely to have an important impact on the spread of metamitron resistant biotypes.

Sensitivity of Echinochloa muricata and Echinochloa crus-galli to HPPD- and ALS-inhibiting herbicides in corn.

Until recently Echinochloa muricata var. microstachya Wiegand (rough barnyardgrass), an alien species native to North America, was completely overlooked in Belgium due to its close morphological resemblance to Echinochloa crus-galli (L.) P. Beauv. (barnyardgrass). E. muricata var. microstachya has gradually spread and is now locally naturalized and abundant in and along maize fields. One of the possible reasons for its expansion in maize fields, besides e.g. the lack of crop rotation, might be a lower sensitivity to postemergence herbicides acting against panicoid grasses, in particular 4-hydroxyphenyl pyruvate dioxygenase (HPPD)-inhibiting herbicides and acetolactate synthase (ALS) inhibiting herbicides. Dose-response pot experiments were conducted in the greenhouse to evaluate the effectiveness of four HPPD-inhibitor herbicides [topramezone (ARIETTA), mesotrione (CALLISTO), tembotrione (LAUDIS), sulcotrione (MIKADO) and the ALS-inhibitor herbicide nicosulfuron (KELVIN) for controlling local populations of E. crus-galli and E. muricata. Pots were planted with 25 seeds, thinned afterwards to 5 plants (one week after sowing) and irrigated by overhead sprinklers. Herbicides were applied at the 3-4 leaf stage (BBCH stage 13-14). Fresh biomass was harvested 28 d after treatment. In another dose-response pot experiment, the influence of leaf stage at time of herbicide application on efficacy of topramezone for (rough) barnyardgrass control was evaluated. Sensitivity to HPPD-inhibitor herbicides topramezone and sulcotrione was significantly lower for E. muricata populations than for E. crus-galli populations. However, nicosulfuron sensitivity of both species was similar. Compared to E. crus-galli, sensitivity of E. muricata to topramezone was more dependent on leaf stage. Due to the intragenus variability in sensitivity to HPPD-inhibitor herbicides, higher awareness is required for presence of E. muricata plants in maize fields in order to avoid insufficient "barnyardgrass" control.

Weed seed bank response to 12 years of different fertilization systems.

Fertilizer amendments can impact weed populations in a variety of ways. This study evaluated the effects of 12 year-long applications of different fertilization systems on size and composition of the weed seed bank in a conventionally managed maize monoculture field. Fertilization systems included all factorial combinations of two dairy cattle slurry rates, three vegetable, fruit and garden waste (VFG) compost rates, and three synthetic N fertilizer rates. Soil samples were taken in each subplot in May 2008 after sowing and prior to herbicide application. Residues recovered from soil samples were tested for weed seedling emergence to characterize soil seed banks. Total weed seed bank density was affected by mineral N fertilization but not by compost or animal slurry application. Weed seed bank composition was related to compost amendment and mineral N fertilization. Annual compost amendments reduced seed bank density of some persistent species (e.g., Chenopodium album and Solanum nigrum) irrespective of mineral N fertilization. Compost is a promising tool for incorporation into integrated weed control strategies aimed at reducing weed seed bank persistence.

Diseases on wheat and triticale under the growing conditions of Lubumbashi (Congo RD).

The food production in Katanga is inadequate and causes food insecurity for more than 400.000 people. Nowadays the Katanga province relies for more than 75 % on imported wheat and wheat flour from neighbouring countries. The absence of adapted germplasm is one of the mean reasons for the low production levels of small grains and as consequence the disinteresting of farmers for producing wheat. To select well adapted genotypes a screening test with wheat (T. aestivum) and triticale (x Triticosecale Wittm.) was establish during the rainy season of 2006-2007 at the farm Kasapa (25 km outside Lubumbashi). Glume blotch (S. nodorum teleomorph: Leptosphaeria nodorum) was the most dominant disease during the rainy season 2006 - 2007. Glume blotch could be detected on leaves and ears of wheat as well as of triticale. Fusarium head blight (Fusarium sp. teleomorph: Gibberella sp.) was also present but to a less extend. Rust or mildew fungus were not recorded on any genotype. The disease pressure made it possible to screen more disease tolerant genotypes of wheat and triticale. The differences were most clear for ear glume blotch but especially on triticale differences between FHB tolerant and susceptible genotypes could be made. For triticale and wheat respectively 25 and 32 % of the genotypes were put in the breeding pole to select new varieties.

Impact of field margin vegetation and herbage removal on ingrowing and anemochorous weeds.

This research studies the effect of different ways to establish and to maintain unfertilised field margins on the development of potential weed plants and seed dispersal into adjacent crops. Plant communities in field margins either developed spontaneously or were sown with different seed mixtures of grasses and forbs. Margins were mown twice a year and the cuttings were either removed or not. Three years after establishment, the importance of important weeds Elymus repens, Cirsium arvense and Urtica dioica was significantly higher in the unsown community or when cuttings were not removed after mowing. Seed dispersal from the margin into adjacent crops was important in the unsown community during the first year after establishment. Between 82% and 99% of the seeds were disseminated within a distance of 4 m from the margin strip. In order to minimize the dissemination of weed species and invasion by noxious vegetatively propagated weeds it is recommended to establish a field margin by sowing and to remove the cuttings after each mowing cut.

Biodiversity and agro-ecology in field margins.

This multidisciplinary study investigates agro-ecological functions (nature conservation, agriculture, environment) and implications of newly created, mown sown and unsown field margin strips installed on ex-arable land to increase biodiversity. From conservational concern, the development of species rich field margin strips was not strongly affected by the installed type of margin strip since species diversity converged over time, whether strips were sown or not. Convergence between unsown and sown margin strips occurred also in terms of species composition: unsown and sown strips became similar over time. Mowing without removal of cuttings significantly reduced species richness, yielded more grassy margin strips and delayed similarity in species composition between sown and unsown margin strips. Species richness on the longer term was not significantly affected by light regime nor by disturbance despite significant temporary effects shortly after the disturbance event. On the contrary vegetation composition in terms of importance of functional groups changed after disturbance: the share of spontaneous species within functional groups increased resulting in higher similarity between the sown and unsown vegetation. Furthermore risk of invasion was highest in the disturbed unsown community on the unshaded side of a tree lane. A positive effect of botanical diversity on insect number and diversity was found. However the effects of botanical diversity on insect number was mediated by light regime. At high light availability differences between plant communities were more pronounced compared to low light availablilty. The abundance of some insect families was dependent on the vegetation composition. Furthermore light availability significantly influenced insect diversity as well as the spatial distribution of families. From agricultural concern, installing margin strips by sowing a species mixture and a mowing regime with removal of cuttings are good practices to diminish the risk of species ingrowth into adjacent crops by creeping roots and rhizomes. Seed dispersal was only problematic one year after the installation of the field margin strips particularly nearby the unsown margin strip and wind-borne seeds were dispersed over limited distances, mainly within 4 m of field margins. Annual herbage yield was not affected by mowing management. DM yield of sown/unsown communities converged over time. Compared to herbage from an intensively managed fertilized grassland, field margin herbage revealed a low feeding value, owing to a low crude protein content, a low digestibility and a high crude fibre content. The unsown community had a higher forage quality than communities sown to bred commercially available grass varieties. Both digestibility and crude protein content decreased over time irrespective of plant community or location. Mid June cuts were more productive than mid September cuts but digestibility and crude protein content was lower. The use of herbage from field margins as hay for horses or as a component in farmland compost are good alternatives. A strong relation was found between the distribution of pest insects and their antagonist families along field margin strips indicating a status of biological equilibrium. From environmental concern, field margin strips buffered boundary vegetation and watercourses against cropped areas loaded with high levels of mineral nitrogen. Margin strips reduced the mineral nitrogen content of the soil in the margin and mineral nitrogen loss during wintermonths. Mineral nitrogen loss was not affected by field margin type but by distance from the field crop. A minimal width of 5 m is necessary to reach an optimal reduction in mineral soil N and N losses.

Molecular markers for cold tolerance and early vigour in maize (Zea mays L.).

Planting maize earlier than the current guidelines recommend, would give great contributions to ecological and sustainable agriculture. In order to plant maize earlier, maize varieties with good cold tolerance and strong early vigour are required. Therefore cold tolerance and early vigour should be important goals in modern maize breeding programmes. Both traits however have a complex, quantitative genetic background and are therefore not easily introduced into modern maize varieties. Marker assisted selection (MAS) can improve the efficiency of breeding activities. In this research project we aim to identify the molecular markers for cold tolerance and early vigour in one of our breeding populations through a QTL analysis. So far nine QTLs for cold tolerance and six QTLs for early vigour could be identified and there is even one QTL in common for the two traits under investigation. The analysis of more populations should reveal whether or not these QTLs might be useful in maize breeding programmes over the world.

Seed vigour in Iranian wheat seeds exposed to cold condition.

Cold stress occurring in the seedbed of winter wheat at the end of autumn results in reduced emergence, even of undeteriorated seed lots (which have not been subjected to a long period of storage and have not been kept in bad storage conditions). The purpose of the present study was to determine the ability of different wheat cultivars at emerging at low field temperatures and the usefulness of a number of laboratory tests in predicting relative emergence of undeteriorated seed lots of different wheat cultivars. Due to genotype variability there were different categories of vigour tested through field and laboratory tests. There were no significant correlations between laboratory tests and field emergence. Our results suggest that conventional vigour tests like standard germination and accelerated ageing do not have enough capacity for identifying genotype differences when emerging in cold conditions.