Winter Oilseed Rape Crops Research Articles

Tillage Practices Effect on Root Distribution and Variation of Soil CO2 Emission under Different Cropping Strategies

Conservation soil management strategies, particularly no-tillage and cropping strategies, have become an effective and widely adopted practice that has a direct influence on root parameters and mitigation of greenhouse gasses. However, the effect of different tillage and cropping strategies on root growth in field conditions is rarely studied. The study aimed to quantify and characterise the relationship between root network development and CO2 emission and how these parameters are affected by different cropping and tillage strategies. Five different crop rotations were tested, with or without the inclusion of catch crops (CC), by growing them in the soil where different tillage practices were applied. Selected cropping strategies differed among themselves in terms of the frequency of CC grown per rotation. The data revealed that in NT treatments, the CO2 emission (both autotrophic and heterotrophic simultaneously) was 25% higher than in CT. The cropping strategies were identified as an important factor influencing CO2 emissions. An increase in CO2 emission varied between 30 and 35% depending on the share of legume and CC inclusion. The frequency of CC grown per rotation has had an effect on the rate of CO2 emission. The cropping strategy when CC was grown every year showed the lowest amount of CO2 (by 26%), while in other cropping strategies, when CC was grown once or twice per rotation, significantly higher CO2 emissions were observed. Root growth and their development were significantly affected (p < 0.05) by soil depth and cropping strategies concerning root length and root volume changes. The inclusion of CC into the rotations led towards a decrease in root volume (by 21%). Root length (R2 = 0.45; p < 0.05) and root volume (R2 = 0.82; p < 0.05) had a significant impact on soil CO2 emissions. The results collected from 2021 to 2023 experiments indicated that cropping strategies and CC management areas are important tools not only for the improvement of root parameters but also for understanding how they affect CO2 emissions. The main message for stakeholders is that the cropping strategies diversification with the inclusion of CC every year in a winter oil-seed rape, spring wheat and pea crop rotation (R/W/P + CC) had demonstrated the possibilities to reduce CO2 emission and improve the root network parameters as compared to the monoculture strategy.

Greenhouse Gas Emissions and Crop Yields From Winter Oilseed Rape Cropping Systems are Unaffected by Management Practices

Winter oilseed rape is traditionally established via plough-based soil cultivation and conventional sowing methods. Whilst there is potential to adopt lower cost, and less intensive establishment systems, the impact of these on greenhouse gas emissions have not been evaluated. To address this, field experiments were conducted in 2014/2015 and 2015/2016 to investigate the effects of 1) crop establishment method and 2) sowing method on soil greenhouse gas emissions from a winter oilseed rape crop grown in Ireland. Soil carbon dioxide, nitrous oxide and methane emission measurements were carried out using the static chamber method. Yield (t seed ha−1) and the yield-scaled global warming potential (kg CO2-eq. kg−1 seed) were also determined for each management practice. During crop establishment, conventional tillage induced an initially rapid loss of carbon dioxide (2.34 g C m−2 hr−1) compared to strip tillage (0.94 g C m−2 hr−1) or minimum tillage (0.16 g C m−2 hr−1) (p < 0.05), although this decreased to background values within a few hours. In the crop establishment trial, the cumulative greenhouse gas emissions were, apart from methane, unaffected by tillage management when sown at a conventional (125 mm) or wide (600 mm) row spacing. In the sowing method trial, cumulative carbon dioxide emissions were also 21% higher when plants were sown at 10 seeds m−2 compared to 60 seeds m−2 (p < 0.05). Row spacing width (125 and 750 mm) and variety (conventional and semi-dwarf) were found to have little effect on greenhouse gas emissions and differences in seed yield between the sowing treatments were small. Overall, management practices had no consistent effect on soil greenhouse gas emissions and modifications in seed yield per plant countered differences in planting density.

Influence of Soil-Borne Inoculum of Plasmodiophora brassicae Measured by qPCR on Disease Severity of Clubroot-Resistant Cultivars of Winter Oilseed Rape (Brassica napus L.).

Use of resistant cultivars is considered the most effective tool in managing clubroot. Three clubroot-resistant commercial winter oilseed rape (OSR) cultivars and a susceptible ‘Cultivar mix’ were evaluated for disease severity index (DSI) and yield performance in field soils, selected for varying abundance of natural inoculum of Plasmodiophora brassicae. Seven field trials were carried out during 2017–2019 in winter OSR crops, and comparative bioassays were performed in a growth chamber. Substantial variation in clubroot infection between years was observed in the field trials. For Cultivar mix, a negative correlation (y = −252.3ln(x) + 58,897.6) was found between inoculum density and seed yield in five trials, whereas no correlation was found for the resistant cultivars. In bioassays, Cultivar mix exhibited a significantly high correlation between DSIb and number of gene copies g−1 soil (R2 = 0.72). For resistant cvs., Mentor and Alister, correlation was R2 = 0.45 and 0.58, respectively, indicating that resistance was under pressure. In field trials, DSIf of the resistant cultivars was lower (<27). The recommendation is thus to use clubroot-resistant cultivars of OSR as part of Integrated Pest Management in situations where abundance of P. brassicae DNA exceeds 1300 gene copies g−1 soil.

MULTISPECTRAL SHEET DIAGNOSTICS OF TECHNOLOGICAL STRESSES ON WINTER RAPES CROPS

Technological stresses are an urgent challenge for winter crops and in particular rapeseed in industrialproduction and in the mass use of agrochemicals and plant protection products. Effective resuscitationmeasures are possible only in the initial stages of the growing season and require reliable and accessibleinformation about the condition of crops. The purpose of the work is to develop an index based on the resultsof analysis of multispectral images with high spatial resolution, obtained by UAVs for the identificationof technological stresses. During field research on October 30, 2019, it was found that in the affected areas,the plants have an abnormal color of the two lower leaves, namely yellow and red. To identify affectedplants, it was proposed to use an image of the object based on the ratio of several channels simultaneously, which allow to distinguish between affected and healthy plants, soil and leaves of abnormal color. Itis proposed to use the RRL (rape red leaf) indices, which are an indicator of the technological nature ofstress, namely RRLgr, designed exclusively for the optical range and the RRLm index (green — G, red — R,border red — Re and near infrared — NIR). Such indices are convenient for monitoring the condition ofrapeseed crops and automated data processing. It was found that when monitoring rapeseed crops in thegrowing season of 6–8 leaves affected by technological stress, using Slantrange 3p height of 100 m, for the indices RRLgr and RRLm is characterized by abnormal leaf color, which was recorded in 1.5 and 2.1%of the total area of plants on the site, respectively. The use of multispectral analysis makes it possible todifferentiate the identification of technological stresses with different manifestations of impression. Ata standard flight altitude for Slantrange 3p of 100 m with the fixation of anomalous color in 1.5% of thetotal area of winter oilseed rape plants is the basis for the organization of additional ground inspection ofthe identified areas of winter oilseed rape crops.

Selectivity and efficacy of herbicide GF-3488, containing synthetic auxins halauxifen-methyl and clopyralid, in winter oilseed rape crops in Ukraine

Halauxifen-methyl is a new synthetic auxin, which in combination with another auxin-like herbicide clopyralid is the active ingredient of complex herbicide GF-3488, that is used for dicotyledonous weeds control in winter oilseed rape crops. The reason of this study was a necessity to test crop selectivity and efficacy of GF-3488 to control dicotyledonous weeds in winter oilseed rape crops in Ukraine and also the possibility of GF-3488 application in the tank mixture with graminicide or/and insecticide to control monocotyledonous weeds and insects. A randomized block experiment was conducted in 2015—2017 in 4 locations. It was found that under spring applying, the GF-3488 is not inferior to another widely used herbicide Galera Super on selectivity to the crop. Herbicide GF-3488 at the rate 1.0 l/ha was significantly better than Galera Super at the rate 0.3 l/ha in controlling of annual dicotyledonous weeds Papaver rhoeas L., Galium aparine L., Consolida regalis S.F. Gray and was effective to control of certain types of cruciferous weeds, which are resistant to Galera Super. Adding graminicide Fusilade Forte and insecticide Nurelle D did not affect the GF-3488 selectivity to the crop and had no negative impact on dicotyledonous weeds control. Efficacy of monocotyledonous weeds control by graminicide did not change in the mixture with GF-3488. It was concluded that herbicide GF-3488 is effective on winter oilseed rape against dicotyledonous weed species. Therefore for the simultaneous control of dicotyledonous and monocotyledonous weeds in winter oilseed rape in the spring after the renewal of the crop vegetation herbicide GF-3488 is advisable to be used in a tank mixture with graminicides, and for simultaneous protection against weeds and pests it can be mixed with insecticides.

The incidence of turnip yellows virus in oilseed rape crops (Brassica napusL.) in three different regions of England over three consecutive growing seasons and the relationship with the abundance of flyingMyzus persicae

AbstractTurnip yellows virus (TuYV) is the most important virus infecting oilseed rape in the United Kingdom. The incidence and spatial distribution of TuYV in winter oilseed rape (WOSR) crops in three regions of England were determined over three growing seasons. Leaf samples were collected from three fields in each region, in autumn (November–December) and spring (April) of the three crop seasons and tested for virus presence by enzyme‐linked immunosorbent assay. Infection was detected in all fields except one. Higher TuYV incidences were recorded in 2007–2008 (≤89%) and 2009–2010 (≤100%) crop seasons than in 2008–2009 (≤24%). Highest incidences were recorded in Lincolnshire (≤100%), followed by Warwickshire (≤88%), with lowest incidences in Yorkshire (1–74%). There was a significant increase in incidence detected between autumn and spring sampling in eight fields, a significant decrease in one field and no significant change in 18 fields. Rothamsted Insect Survey suction trap data for the aphidMyzus persicaein Lincolnshire, Warwickshire and Yorkshire revealed two peaks of flight activity in most years (2007–2009). The second peak (September–November) coincided with emergence of WOSR. The highest cumulative (August–November) trap catches in the three regions during the three crop seasons occurred in Lincolnshire and the lowest in Yorkshire; catches in autumn 2009 were highest and lowest in autumn 2008. Regression analysis revealed a highly significant association between the cumulative numbers ofM. persicaecaught in the suction traps closest to the crops between August and November each year and the incidence of TuYV detected in the WOSR crops in the autumn of each year. Results are discussed in the light of factors affecting the spread of TuYV and future possibilities for control.

Genetic diversity and virulence of Xanthomonas campestris pv. campestris isolates from Brassica napus and six Brassica oleracea crops in Serbia

The present study provides insight into the diversity of 147 Xanthomonas campestris pv. campestris (Xcc) isolates obtained from six Brassica oleracea vegetable crops (broccoli, cabbage, cauliflower, collard greens, kale, kohlrabi) and the winter oilseed rape crop Brassica napus, collected from different regions in Serbia in 2014. The XCF/XCR pathovar‐specific primer set was used for fast preliminary identification. In repetitive sequence‐based PCR (BOX, ERIC and REP) of all isolates, a higher level of genetic diversity was found in winter oilseed rape isolates compared to isolates from the other hosts. ERIC and REP‐PCR showed the highest heterogeneity, with 10 and nine banding patterns, respectively. The REP‐PCR results showed the highest correlation (70%) with those obtained with multilocus sequence analysis (MLSA), performed with 10 housekeeping genes (fusA, gap‐1, gltA, gyrB1, lacF, lepA, rpoD, dnaK, fyuA and gyrB2). Three distinct phylogenetic groups of winter oilseed rape isolates were detected using MLSA. Two genes, gltA and rpoD, showed the greatest ability to identify and discriminate winter oilseed rape Xcc isolates from isolates of the other six hosts. The lepA gene exhibited specific three‐nucleotide changes in sequences of some of the isolates. Results of virulence testing of 18 representative isolates showed statistically significant host–pathogen specialization for Xcc isolates from winter oilseed rape, cauliflower, kale and kohlrabi. In conclusion, oilseed rape isolates are more genetically diverse and show greater specialization to their host in comparison to the rest of the tested isolates from other brassica hosts.

Rainfall interception by winter rapeseed in Brandenburg (Germany) under various nitrogen fertilization treatments

Oilseed rape (Brassica napus L.) is the major oil crop in Europe and Germany but its hydrological functioning is poorly understood. Studies on the interception processes in oilseed rape have been lacking until the present. The interception of rainfall by oilseed rape is expected to vary in response to substantial changes in canopy structure throughout the cropping cycle and fertilization treatment. To determine evaporation of intercepted water, field measurements of a winter oilseed rape crop were conducted for different stages of development and five treatments of fertilization (0, 60, 120, 180 and 240 kg N/ha). Precipitation (P) and throughfall (TF) were measured hourly, along with vegetation structure measurements of the leaf area index (LAI). A range of 0–21% for the percentage of stemflow (SF) of P was estimated from soil moisture measurements. For the vegetation period from March to June the cumulative P of 112 mm was converted into 49 mm TF (44%). The inferred evaporation of intercepted water (I) was 63 mm (56%). There was a gradual and clear increase in I from 45% to 67%, reflecting the increasing fertilization treatments. Hence, less soil water was available with increasing amounts of fertilization, since the water fraction evaporating from the canopy increases. Plant architecture, LAI and meteorological conditions during the cropping cycle appeared to be the main factors determining I. For irrigation planning and water use, studies of the evaporation of intercepted water must be considered.

The impact of non-chemical weed control methods on the disease occurrence in the organically grown winter oilseed rape crop

The impact of non-chemical weed control methods on the disease occurrence in the organically grown winter oilseed rape crop

Evaluation of hybrid and population cultivars on standard and high-input technology in winter oilseed rape

ABSTRACTThe problem raised here is the intensification of technology in field crops of winter oilseed rape. Is there a justification for this by explaining what relationship between the yield and individual yielding traits are formed in hybrid and population cultivars. During years 2012–2015 field studies to evaluate five hybrid and five population cultivars response on the standard and high-input technology in winter oilseed rape production have been executed in Poland. High-input technology included: double foliar application (in autumn, and in spring) of micro-nutrients, additional top fertilisation of 40 kg N per ha in spring, double application of the amino-acid bio-stimulators, and additional growth regulator. According to the principle component analysis made for both technologies it was found that hybrids and population cultivars displayed varied response which is explained here on the basis of morphological, growth, and yield elements. The high-input technology improved the yield responded elements e.g. number of siliques and number of seeds per silique as well as winter hardiness. This impact was more evident for population cultivars than for hybrids. We state that high-input technology, as the proposal in this paper, that provided 9.6% increase in seed yield, is biologically justified for winter oilseed rape crop and can be recommended in North and central European countries.

The impact of non-chemical weed control methods and biopreparations on winter oilseed rape preparation for over-wintering and productivity

The current study was aimed to establish the impact of non-chemical weed control methods (thermal, mechanical andsmothering) and biopreparations on winter oilseed rape (Brassica napus L.) preparation for over-wintering and productivity under the conditions of the organic farming system. During the 2014–2016 period, a field experiment was conducted at the Experimental Station of Aleksandras Stulginskis University on Calc(ar)i-Endohypogleyic Luvisol (LVg-n-w-cc). The field experiment treatments were the following: Factor A – non-chemical weed control methods: 1) thermal (water steam), 2) mechanical (inter-row loosening), 3) smothering (self-regulation, sowing with narrow inter-rows); Factor B – application of biopreparations: 1) without application, 2) with application. During the period of autumn vegetation, in the smothering method plots, where the winter oilseed rape crop density was 1.5–2.4 times lower than that in the plots of thermal and mechanical weed control methods, the significantly highest aboveground mass of plant, number of leaves per plant, diameter of root collar, root area, total root length, root biomass of plant and leaf area of plant were determined, and in 2015 the highest chlorophyll index was measured in the leaves. In 2014 the application of biopreprations in the smothering method plots significantly increased the aboveground mass of plant (41.3%), the total root length (33.2%) and the root biomass of plant (28.0%). In 2004 the diameter of winter oilseed rape root collar depended on the leaf area of plant (r = 0.83, P &lt; 0.05) and the root area of plant (r = 0.86, P &lt; 0.05), and in 2015 it depended on the leaf area of plant (r = 0.89, P &lt; 0.05), the root area (r = 0.99, P &lt; 0.01), the total root length (r = 0.98, P &lt; 0.01) and the root biomass of plant (r = 0.99, P &lt; 0.01). Positive, strong and very strong, and statistically significant relationships were established between the leaf area of oilseed rape and the root area, the total root length and the root biomass of plant. In the spring of 2015, during the renewed oilseed rape vegetation stage, the highest crop density (98.0 units m–2) and over-wintering (96.0%) were obtained in the plots of the mechanical weed control method in combination with biopreparations. In the spring of 2016, different nonchemical weed control methods and biopreparations did not have any significant effect on the oilseed rape over-wintering and the crop density. In 2015, different non-chemical weed control methods did not have any significant influence on oilseed rape biometric parameters before harvesting. In 2016, in the smothering method plots a significantly lower mass of oilseed rape and the number of branches per plant were formed compared to those of other used treatments. The highest number of pods per plant was determined in the smothering method plots in combination with biopreparations. In 2015 biopreprations in the smothering method plots significantly increased the 1 000 seed mass, and in 2016 they increased the number of pods per plant, respectively 7.2 and 35.6%. In the droughty year of 2015, the significantly highest winter oilseed rape seed yield was recorded in the plots of the mechanical weed control method, and in the moist year of 2016, the highest yield was in the smothering method plots with biopreparations. In 2015 biopreprations significantly increased the oilseed rape seed yield in the plots of thermal and mechanical weed control methods, and in 2016 they increased the yield in the smothering method plots, respectively 43.4, 25.1 and 51.5%. In 2015 the winter oilseed rape seed yield depended on the crop density (r = 0.86, P &lt; 0.05) and the plant height (r = 0.94, P &lt; 0.01), and in 2016 it depended on the number of pods per plant (r = 0.98, P &lt; 0.01) and the plant height (r = 0.85, P &lt; 0.05).

Spatial distribution of cabbage root maggot (Delia radicum) and clubroot (Plasmodiophora brassicae) in winter oilseed rape crops in the Czech Republic

The amount and spatial distribution of plants afflicted with cabbage root maggot (Delia radicum; CRM) and clubroot (Plasmodiophora brassicae) in winter oilseed rape crops were assessed in the Olomouc region (Northern Moravia, Czech Republic) over the course of 2012–2014. A total of 16 commercial rape fields were included in the assessments. Plants with tumours showed a significantly lower (P &amp;lt; 0.001) level of infestation induced by CRM (24% of plants infested) compared to plants without tumours (37% of plants infested). According to a generalised linear mixed model, plants with thicker hypocotyls are predisposed to significantly higher levels (P &amp;lt; 0.001) of root surface damage induced by CRM. The correlation analysis indicates rather weak or intermediate levels of correlation between the two variables (hypocotyls thickness × root surface damage induced by CRM). Both CRM and clubroot symptomatic plants showed a significant tendency for aggregation in rape crops, but not in all cases. Distributions of CRM and clubroot symptomatic plants were either significantly spatially dissociated or not associated in crops. Ovipositing D. radicum females showed some tendency to avoid zones with higher number of plants infected by P. brassicae. Distributions of CRM and hypocotyl thickness levels were significantly spatially associated in crops in several cases.

Spatio-temporal Distributions and Associations of Cabbage Stem Weevil (Ceutorhynchus Pallidactylus Marsham, 1802) and Pollen Beetle (Brassicogethes Aeneus Fabricius, 1775) in winter oilseed rape

From 2013 to 2015 the within-field spatio-temporal distributions and interactions between Ceutorhynchus pallidactylus and Brassicogethes aeneus in winter oilseed rape crops were assessed using SADIE analysis (Spatial Analysis by Distance IndicEs) and Quick association analysis. A significant tendency for aggregation was recorded in C. pallidactylus males in the crop in both 2013 and 2015. Females showed a high tendency towards aggregation only in 2013. Both sexes were significantly associated in crops in 2013 and 2015. B. aeneus adults showed a high tendency towards aggregation in all three years. From the three seasons the cumulative distributions (based on the sums of insect catches in traps for the individual dates) of males and females of C. pallidactylus were significantly associated with the cumulative distribution of B. aeneus adults only in 2013. Contrary to this, an almost significant dissociation between cumulative distributions of C. pallidactylus males and B. aeneus adults was recorded in 2014.

Undersowing winter oilseed rape with frost-sensitive legume living mulches to improve weed control

Living mulches are generally seen as a possible way to decrease the reliance on pesticides. We investigated the effect of a frost-sensitive legume living mulch on weed control during the autumn and cash crop performance, in winter oilseed rape crops. A field trial was carried out over two years, comparing seven legume species—fenugreek, spring faba bean, grass pea, lentil, field pea, berseem clover and spring common vetch—and three legume mixtures, as living mulches, in crops with two levels of soil mineral nitrogen content before sowing. The presence of the legume living mulch decreased weed abundance before winter. Field pea, berseem clover, common vetch and the common vetch/faba bean/berseem clover mixture were particularly effective, regardless of the growing conditions, decreasing weed abundance by 20–75% with respect to that in the crop grown alone, in the absence of herbicide application. Weed abundance before winter was negatively correlated with total intercrop biomass, and this relationship was dependent on the legume species considered and soil mineral nitrogen content. As with other legume intercrops, the level of soil mineral nitrogen had a strong influence on intercrop structure, modifying the proportion of legume biomass produced. The legume/oilseed rape biomass ratio was also found to be a useful indicator in all growing conditions: the higher the ratio, the more efficient the weed control. However, a high ratio was associated with a higher risk of competition with the cash crop. The choice of the most appropriate legume living mulch is therefore a compromise between the anticipated ecosystem services and the potential disservices provided by the legume mulch. The introduction of a legume living mulch did not entirely prevent weed growth, but was clearly a relevant agroecological solution for decreasing herbicide, while increasing the sustainability and diversity of weed-control strategies in cropping systems.

The potential of decision support systems to improve risk assessment for pollen beetle management in winter oilseed rape.

BACKGROUNDThe reliance on and extensive use of pyrethroid insecticides have led to pyrethroid resistance in pollen beetle (Meligethes aeneus). Widespread adoption of best practice in pollen beetle management is therefore needed. Decision support systems (DSSs) that identify the risk period(s) for pest migration can help to target monitoring and control efforts, but they must be accurate and labour efficient to gain the support of growers. Weather data and the phenology of pollen beetles in 44 winter oilseed rape crops across England over 4 years were used to compare the performance of two risk management tools: the DSS proPlant expert, which predicts migration risk according to a phenological model and local weather data, and ‘rule‐based advice’, which depends on crop growth stage and a temperature threshold.RESULTSBoth risk management tools were effective in prompting monitoring that would detect breaches of various control thresholds. However, the DSS more accurately predicted migration start and advised significantly fewer days of migration risk, consultation days and monitoring than did rule‐based advice.CONCLUSIONThe proPlant expert DSS reliably models pollen beetle phenology. Use of such a DSS can focus monitoring effort to when it is most needed, facilitate the practical use of thresholds and help to prevent unnecessary insecticide applications and the development of insecticide resistance. © 2015 Rothamsted Research Ltd. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Weed flora shifts and specialisation in winter oilseed rape in France

SummaryTemporally repeated data sets can provide useful information about the management practices governing changes in the arable weed flora. This study aimed (i) to investigate changes in the most common weed species in winter oilseed rape crops in France between the 1970s and the 2000s and (ii) to pinpoint the main plant biological traits and associated management practices underlying the development of a specific weed flora in this crop. We compared two large‐scale surveys covering France in the 1970s and the 2000s, the later survey including several floristic samplings, on two dates, and both herbicide‐free control and treated plots. This last survey aimed to identify the species best able to maintain high densities over a growing season of oilseed rape. Since the 1970s, the frequency of two‐thirds (69%) of the 26 most common species has changed, spectacularly in some cases, with several species once considered rare becoming very common (e.g. Geranium dissectum) and, conversely, some formerly common species becoming rarer (e.g. Stellaria media). Our results indicated a general strong increase in specialist weeds of oilseed rape. Weed species success was favoured by tolerance to oilseed rape herbicides and germination synchronous with the crop. The proportion of specialist oilseed rape weed species tended to increase with herbicide treatment intensity and to decrease with increases in the proportion of spring‐sown crops in the rotation. Changes to the rotation may therefore constitute an additional or alternative means of controlling some weeds well adapted to oilseed rape crops.

An updated model for nitrate uptake modelling in plants. I. Functional component: cross-combination of flow-force interpretation of nitrate uptake isotherms, and environmental and in planta regulation of nitrate influx.

In spite of major breakthroughs in the last three decades in the identification of root nitrate uptake transporters in plants and the associated regulation of nitrate transport activities, a simplified and operational modelling approach for nitrate uptake is still lacking. This is due mainly to the difficulty in linking the various regulations of nitrate transport that act at different levels of time and on different spatial scales. A cross-combination of a Flow-Force approach applied to nitrate influx isotherms and experimentally determined environmental and in planta regulation is used to model nitrate in oilseed rape, Brassica napus. In contrast to 'Enzyme-Substrate' interpretations, a Flow-Force modelling approach considers the root as a single catalytic structure and does not infer hypothetical cellular processes among nitrate transporter activities across cellular layers in the mature roots. In addition, this approach accounts for the driving force on ion transport based on the gradient of electrochemical potential, which is more appropriate from a thermodynamic viewpoint. Use of a Flow-Force formalism on nitrate influx isotherms leads to the development of a new conceptual mechanistic basis to model more accurately N uptake by a winter oilseed rape crop under field conditions during the whole growth cycle. This forms the functional component of a proposed new structure-function mechanistic model of N uptake.

Detection and quantification of airborne inoculum of Pyrenopeziza brassicae in Polish and UK winter oilseed rape crops by real-time PCR assays

Following a sudden outbreak of light leaf spot disease in Polish winter oilseed rape crops at the beginning of the last decade, volumetric spore traps installed around the country were used for the detection of ascospores, which constitute the primary inoculum of Pyrenopeziza brassicae, the causal organism. In 2004–2008, weather conditions that were adverse to the development of the pathogen appeared to have hindered the macroscopic signs of light leaf spot disease symptoms on oilseed rape, even in Pomerania, a region in north Poland, which cultivates the crop intensively and is favourable for the disease. Recently, however, the development of β-tubulin-based primers and dual labelled fluorescent probes has enabled the detection of minute quantities of P. brassicae DNA that correlated highly and positively with low abundance of inoculum of the pathogen in air samples. Depending on the season, the Spearman's correlation rank between spore abundance obtained by light microscopy and P. brassicae DNA yield determined by quantitative polymerase chain reaction (qPCR) on extracts from spore sampler tapes varied from 0.256 to 0.562. These primers and probe also detected P. brassicae in DNA extracted from tapes of spore traps operated in the autumn of 2006 and 2007 within field sown winter oilseed rape crops in Harpenden, southern UK.

Application of a robust experimental method to study soil warming effects on oilseed rape

Climate change is expected to cause a mean annual temperature increase in Germany of up to 4°C by 2100. Hence, field manipulation experiments for the assessment of the impact of global warming on agricultural production are needed to supplement existing modeling approaches. Here, we present a soil warming facility adapted for field crops, enabling common agronomic practices, including soil tillage, to be carried out while simulating natural warming scenarios. The experimental setup consists of buried heating cables and a fully computerized temperature control and data logging system. Treatments reflected medium- (up to 2050) and long-term (up to 2100) climate warming scenarios compared to the unheated (ambient) control. In a year-round experiment, there were no technical problems and the programmed temperature offset was kept stable at two levels, +1.6°C (±0.17°C) or +3.2°C (±0.27°C) above ambient throughout the experiment. We assessed warming effects on the plot microclimate as well as on biological parameters in a winter oilseed rape crop (Brassica napus L.). Growth stages were advanced in October and April, and plant length before flowering was significantly higher in the warmest treatment compared to the unheated control plots. Overall, our method proved stable and reliable under field conditions enabling common agronomic practices to be carried out while observing the effects of increased soil temperatures.

SIPPOM-WOSR: A Simulator for Integrated Pathogen POpulation Management of phoma stem canker on Winter OilSeed Rape: I. Description of the model

To durably control phoma stem canker ( Leptosphaeria maculans/ Leptosphaeria biglobosa) in oilseed rape by preserving the efficacy of specific resistances, the design of cropping systems is required, combining different aspects of crop management over time and at the regional scale. Modelling is a practical means to do so. To this end, the structure of SIPPOM, a Simulator for Integrated Pathogen POpulation Management, is presented. By linking epidemiological, population and crop model approaches, it simulates both the quantitative evolution (size) and qualitative evolution (genetic structure) of L. maculans population under the influence of various cropping systems. It involves five sub-models: (i) primary inoculum production; (ii) ascospore dispersal; (iii) crop development; (iv) plant infection, disease severity, and yield loss; and (v) changes in the genetic structure of pathogen populations over time. The input variables are weather data, soil characteristics, the description of cropping systems (crop sequence and winter oilseed rape crop management, including cultivars, sowing, fungicide, and tillage) and their spatial distribution (the model is spatially explicit), plus the initial size and genetic structure of pathogen populations. The genetic evolutionary forces taken into account are migration, selection, and recombination. The model simulates disease severity and the genetic structure of the pathogen population, in addition to the attainable yield less yield loss caused by the disease. The economic and environmental performances of the simulated strategies are computed using technical operation costs, crop prices, and yields. The underlying hypotheses are discussed in light of advantages and possible improvements of the model. Possible uses of SIPPOM are proposed with respect to the design of collective strategies for the durable control of phoma stem canker on winter oilseed rape at a regional scale.