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8 result(s) for "Bazot, Mathieu"
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Characterization of the pollen beetle, Brassicogethes aeneus, dispersal from woodlands to winter oilseed rape fields
Many crop pests rely on resources out of crop fields; understanding how they colonize the fields is an important factor to develop integrated pest management. In particular, the time of crop colonization and damage severity might be determined by pest movements between fields and non-crop areas. Notably, the pollen beetle, Brassicogethes aeneus, previously named Meligethes aeneus, one of the most important pests of winter oilseed rape, overwinters in woodlands. As a result, its abundance increases in oilseed rape fields near wooded areas. Here, we assessed the spatio-temporal patterns of the dispersal from woodlands to oilseed rape fields in diversified landscapes of a same region. We observed on four dates the abundance of pollen beetles in 24 fields spread in the Eure department, France. We modeled the abundance as a result of the dispersal from the neighboring woodlands. We compared the modalities of dispersal corresponding to different hypotheses on the dispersal origin, kernel shape and sources of variability. Within oilseed rape the distance to the edges of woodlands is not the main determinant of pollen beetle abundance. On the contrary, the variability of the abundance between fields is largely explained by the dispersal from neighboring woodlands but there is considerable variability between dates, sites and, to a lesser extent, between fields. The two dispersal kernels received similar support from the data and lead to similar conclusions. The mean dispersal distance is 1.2 km but seems to increase from a few hundred meters the first week to more than two kilometers the fourth, allowing the pollen beetles to reach more distant OSR fields. These results suggest that early varieties away from woodlands and late varieties close to the woodlands may limit attacks at the time when oilseed rape is the most sensitive.
Crop Management Affects the Performance of a Winter Pea–Wheat Intercrop
Cereal–legume intercropping systems may show improved agronomic and environmental performance over sole crops depending on the intercrop management. This study aimed at investigating the effect of sowing and fertilizer management on the performance of a winter pea (Pisum sativum L.)–wheat (Triticum aestivum L.) intercrop. A 2‐yr experiment was performed in Grignon, France. Intercrop management strategies varied in sowing proportion relative to the sowing density of sole crops (50:50, 66:33, and 50:70 for pea and wheat, respectively) and N fertilization (without N fertilization, conventionally fertilized, and overfertilized at different dates). Conventionally managed sole wheat and sole pea were used as controls. The total grain yield, wheat yield proportion at harvest, yield components, N efficiency, grain protein concentration, residual soil mineral N after harvest, and land equivalent ratios (LER) were compared. The fertilized 50:50 intercrop was a good compromise between production (yields and wheat protein concentration), N efficiency, and limited residual soil N. The unfertilized 50:50 intercrop had the lowest grain yields and wheat protein concentration. An early overfertilization increased the proportion of wheat yield at harvest, whereas a late overfertilization increased the wheat grain protein concentration. Increasing the proportion of pea at sowing was a good way to produce more pea yield. Increasing the sown wheat proportion with N fertilization led to a higher proportion of wheat yield at harvest but did not improve the wheat grain protein concentration. These results indicate that agronomic management markedly impacts intercrop performance, and management practices can be adjusted to meet farmers’ production targets. Sowing rate and N fertilization impacts the agronomic performances of a pea–wheat intercrop. Intercrop management has to be adapted to the farmer's production targets. Conventionally managed intercrop is a compromise between production and environmental impacts. Overfertilization may increase wheat production and protein concentration. Producing more pea implies increasing pea proportion at sowing and decreasing N fertilization.
Analysis of young Miscanthus × giganteus yield variability: a survey of farmers’ fields in east central France
Miscanthus × giganteus is often regarded as one of the most promising crops to produce bioenergy because it is renowned for its high biomass yields, combined with low input requirements. However, its productivity has been mainly studied in experimental conditions. Our study aimed at characterizing and explaining young M. giganteus yield variability on a farmers’ field network located in the supply area of a cooperative society in east central France. It included the first three growth years of the crop. We defined and calculated a set of indicators of limiting factors that could be involved in yield variations and used the mixed‐model method to identify those explaining most of the yield variation. Commercial yields averaged 8.1 and 12.8 t DM ha−1 for the second and third growth year, respectively. However, these mean results concealed a high variability, ranging from 3 to 19 t DM ha−1. Commercial yields, measured on whole fields, were on average 20% lower than plot yields, measured on a small area (two plots of 25 m2). Yields were found to be much more related to shoot density than to shoot mass, and particularly to the shoot density established at the end of the planting year. We highlighted that planting success was decisive and was built during the whole plantation year. Fields with the lowest yields also had the highest weed cover, which was influenced by the distance between the field and the farmhouse, the preceding crop and the soil type. Our findings show that growing young M. giganteus on farmers’ fields involves limiting factors different from those commonly reported in the literature for experimental conditions and they could be useful to assess the economic and environmental impacts of growing M. giganteus on farmers’ fields. They could also stimulate the discussion about growing bioenergy crops on marginal lands.
Analysis of young Miscanthus giganteu s yield variability: a survey of farmers' fields in east central France
Miscanthus giganteus is often regarded as one of the most promising crops to produce bioenergy because it is renowned for its high biomass yields, combined with low input requirements. However, its productivity has been mainly studied in experimental conditions. Our study aimed at characterizing and explaining young M. giganteus yield variability on a farmers' field network located in the supply area of a cooperative society in east central France. It included the first three growth years of the crop. We defined and calculated a set of indicators of limiting factors that could be involved in yield variations and used the mixed-model method to identify those explaining most of the yield variation. Commercial yields averaged 8.1 and 12.8 t DM ha super(-1) for the second and third growth year, respectively. However, these mean results concealed a high variability, ranging from 3 to 19 t DM ha super(-1) . Commercial yields, measured on whole fields, were on average 20% lower than plot yields, measured on a small area (two plots of 25 m super(2)). Yields were found to be much more related to shoot density than to shoot mass, and particularly to the shoot density established at the end of the planting year. We highlighted that planting success was decisive and was built during the whole plantation year. Fields with the lowest yields also had the highest weed cover, which was influenced by the distance between the field and the farmhouse, the preceding crop and the soil type. Our findings show that growing young M. giganteus on farmers' fields involves limiting factors different from those commonly reported in the literature for experimental conditions and they could be useful to assess the economic and environmental impacts of growing M. giganteus on farmers' fields. They could also stimulate the discussion about growing bioenergy crops on marginal lands.
Assessing nitrate leaching during the three‐first years of Miscanthus × giganteus from on‐farm measurements and modeling
Miscanthus × giganteus is often regarded as one of the most promising crops to produce sustainable bioenergy. This perennial crop, renowned for its high productivity associated with low input requirements, in particular regarding fertilizers, is thought to have low environmental impacts, but few data are available to confirm this. Our study aimed at assessing nitrate leaching from Miscanthus × giganteus crops in farmers' fields, thus including a wide range of soil and cropping system conditions. We focused on the first years of growth after planting as experimental studies have suggested that Miscanthus × giganteus, once established, results in low nitrate leaching. We combined on‐farm measurements and modeling to estimate drainage, leached nitrogen, and nitrate concentration in drainage water in 38 fields located in Center‐East France during two winters (November 2010 to March 2011, November 2011 to March 2012). Nitrate leaching and nitrate concentration in drainage water were on average very low. Nitrate leaching averaged 6 kg N ha−1 whereas nitrate concentration averaged 12 mg l−1. These low values are attributable to the low estimates of drainage water (mean = 166 mm) but also to the low soil mineral nitrogen contents measured at the beginning of winter (mean = 37 kg N ha−1). Our results were, however, very variable, mainly due to the crop age: nitrate leaching and nitrate concentration were critically higher during the winter following the first growth year of Miscanthus × giganteus, reflecting the low development of the crop. This variability was also explained by the range of soil and cropping conditions explored in the on‐farm design: shallow and/or sandy soils as well as fields where establishment failed had a higher risk of nitrate leaching.
Assessing nitrate leaching during the three-first years of Miscanthus giganteu s from on-farm measurements and modeling
Miscanthus giganteus is often regarded as one of the most promising crops to produce sustainable bioenergy. This perennial crop, renowned for its high productivity associated with low input requirements, in particular regarding fertilizers, is thought to have low environmental impacts, but few data are available to confirm this. Our study aimed at assessing nitrate leaching from Miscanthus giganteu s crops in farmers' fields, thus including a wide range of soil and cropping system conditions. We focused on the first years of growth after planting as experimental studies have suggested that Miscanthus giganteu s, once established, results in low nitrate leaching. We combined on-farm measurements and modeling to estimate drainage, leached nitrogen, and nitrate concentration in drainage water in 38 fields located in Center-East France during two winters (November 2010 to March 2011, November 2011 to March 2012). Nitrate leaching and nitrate concentration in drainage water were on average very low. Nitrate leaching averaged 6 kg N ha super(-1) whereas nitrate concentration averaged 12 mg l super(-1). These low values are attributable to the low estimates of drainage water (mean = 166 mm) but also to the low soil mineral nitrogen contents measured at the beginning of winter (mean = 37 kg N ha super(-1)). Our results were, however, very variable, mainly due to the crop age: nitrate leaching and nitrate concentration were critically higher during the winter following the first growth year of Miscanthus giganteu s, reflecting the low development of the crop. This variability was also explained by the range of soil and cropping conditions explored in the on-farm design: shallow and/or sandy soils as well as fields where establishment failed had a higher risk of nitrate leaching.
Assessing nitrate leaching during the three-first years of Miscanthus 3 giganteus from on-farm measurements and modeling
Miscanthus × giganteus is often regarded as one of the most promising crops to produce sustainable bioenergy. This perennial crop, renowned for its high productivity associated with low input requirements, in particular regarding fertilizers, is thought to have low environmental impacts, but few data are available to confirm this. Our study aimed at assessing nitrate leaching from Miscanthus × giganteus crops in farmers' fields, thus including a wide range of soil and cropping system conditions. We focused on the first years of growth after planting as experimental studies have suggested that Miscanthus × giganteus, once established, results in low nitrate leaching. We combined on-farm measurements and modeling to estimate drainage, leached nitrogen, and nitrate concentration in drainage water in 38 fields located in Center-East France during two winters (November 2010 to March 2011, November 2011 to March 2012). Nitrate leaching and nitrate concentration in drainage water were on average very low. Nitrate leaching averaged 6 kg N ha−1 whereas nitrate concentration averaged 12 mg l−1. These low values are attributable to the low estimates of drainage water (mean = 166 mm) but also to the low soil mineral nitrogen contents measured at the beginning of winter (mean = 37 kg N ha−1). Our results were, however, very variable, mainly due to the crop age: nitrate leaching and nitrate concentration were critically higher during the winter following the first growth year of Miscanthus × giganteus, reflecting the low development of the crop. This variability was also explained by the range of soil and cropping conditions explored in the on-farm design: shallow and/or sandy soils as well as fields where establishment failed had a higher risk of nitrate leaching.
A Hot Saturn Orbiting An Oscillating Late Subgiant Discovered by TESS
We present the discovery of TOI-197.01, the first transiting planet identified by the Transiting Exoplanet Survey Satellite (TESS) for which asteroseismology of the host star is possible. TOI-197 (HIP116158) is a bright (V=8.2 mag), spectroscopically classified subgiant which oscillates with an average frequency of about 430 muHz and displays a clear signature of mixed modes. The oscillation amplitude confirms that the redder TESS bandpass compared to Kepler has a small effect on the oscillations, supporting the expected yield of thousands of solar-like oscillators with TESS 2-minute cadence observations. Asteroseismic modeling yields a robust determination of the host star radius (2.943+/-0.064 Rsun), mass (1.212 +/- 0.074 Msun) and age (4.9+/-1.1 Gyr), and demonstrates that it has just started ascending the red-giant branch. Combining asteroseismology with transit modeling and radial-velocity observations, we show that the planet is a \"hot Saturn\" (9.17+/-0.33 Rearth) with an orbital period of ~14.3 days, irradiance of 343+/-24 Fearth, moderate mass (60.5 +/- 5.7 Mearth) and density (0.431+/-0.062 gcc). The properties of TOI-197.01 show that the host-star metallicity - planet mass correlation found in sub-Saturns (4-8 Rearth) does not extend to larger radii, indicating that planets in the transition between sub-Saturns and Jupiters follow a relatively narrow range of densities. With a density measured to ~15%, TOI-197.01 is one of the best characterized Saturn-sized planets to date, augmenting the small number of known transiting planets around evolved stars and demonstrating the power of TESS to characterize exoplanets and their host stars using asteroseismology.