Oilseed Rape Production Research Articles

Recommended fertilization practices improve the environmental performance of biodiesel from winter oilseed rape in France

Current assessments of the environmental performance of biofuel chains are fraught by a large degree of variability and uncertainty arising from differences in life cycle inventory data for the feedstock production stage, notably crop yields and emissions of reactive nitrogen. This study sets out to improve the accuracy of these data by combining agro-ecosystem modelling and agronomic survey data, in the context of biodiesel production from winter oilseed rape in France. Crop yields and environmental emissions related to crop farming were simulated over the 2010–2030 time period in 8 administrative regions accounting for most of winter oilseed rape production, and the results were fed into a life cycle assessment (LCA) of biodiesel. The effects of changes in climate scenarios and the improvement of fertilization practices were also examined.Compared to the widely used methodology based on fixed emissions factors, ecosystem modelling led to 29–41% lower estimates for direct nitrous oxide (N2O) emissions, depending on climate scenarios, which emphasizes the importance of taking local factors into account. The life cycle GHG emissions of biodiesel from winter oilseed rape varied starkly across the studied regions, from 20.6 to 25.7 g CO2 eq MJ−1 and from 22.9 to 32.4 g CO2 eq MJ−1 depending on climate scenarios. Overall, biodiesel deployment would abate GHG emissions by 65–78% compared to fossil diesel, not accounting for land use changes effects. Improved fertilization practices mitigated the LCA impact indicators by 3–14%.

Influence of the Semi‐dwarf Growth Type on Seed Yield and Agronomic Parameters at Low and High Nitrogen Fertilization in Winter Oilseed Rape

In cereals like wheat (Triticum aestivum L.) or rice (Oryza sativa L.), a short‐straw ideotype is characteristic for all modern cultivars, mainly due to the use of genes affecting the dwarf genotype. In oilseed rape (Brassica napus L.), several dwarf mutants are known but so far not widely used. An interesting approach is the production of semi‐dwarf hybrids from dwarf and normal‐type parents, which might have an increased harvest index (HI) and a higher grain yield, especially when nitrogen (N) availability is restricted. To this point, no systematic comparison using a large number of semi‐dwarf and normal‐type hybrids has been published. A double haploid (DH) population was developed that was segregating for the bzh dwarf locus with 54 dwarf and 54 normal‐type lines. By crossing with a normal‐type tester, 108 testcrosses were produced with 54 hybrids each of semi‐dwarf and normal types. These were evaluated under high and zero N fertilization in five and seven environments, respectively, for yield and agronomic parameters. Quantitative trait loci (QTL) were estimated for yield‐relevant traits. Semi‐dwarf hybrids had a significantly higher yield compared with normal types in N‐deficient conditions (2.24 and 2.05 Mg ha−1). At an optimal N supply, no significant difference between growth types was found for seed yield. Oil content was slightly lower in semi‐dwarfs under both N treatments, whereas this was compensated by oil yield. All major QTL for plant height, straw yield, HI, and seed yield co‐segregated with the bzh dwarf locus on linkage group A06, indicating that the dwarf gene is not only reducing plant height but also causing increased HI and higher yield under N limitation for semi‐dwarf hybrids. We conclude that semi‐dwarf hybrids are of high interest for the N‐balanced oilseed rape production, especially when N is scarce.

Responses of plant development, biomass and seed production of direct sown oilseed rape (Brassica napus) to nitrogen application at different stages in Yangtze River Basin

Direct sown oilseed rape has been rapidly developed in recent years due to increasing shortage of labor force in the winter oilseed rape (Brassica napus L.) region of Yangtze River Basin. However, the appropriate nitrogen management of the crop has not yet been established, resulting in poor seed yield. Two experiments were conducted, including a pot trial to elucidate the N utilization in different growth periods under sufficient supplies of N and other nutrients, and a field experiment to study the effects of N application rates at different stages on plant development, biomass production, seed yield and N use efficiency of direct sown oilseed rape. The results showed that N applications at different stages extended the growth period of the crop. The vegetative growth was extended more than the reproductive growth by N applied at early stages. Nitrogen application promoted the plant growth center/s leading to high biomass accumulations in different periods. Higher pre-sowing N rates prolonged the fast biomass accumulation period and increased the fastest accumulation speed. The seed yield and NUE of the crop were improved by N applied prior to sowing and at the initiation of stem elongation. The results suggest that, relatively high N rate but not exceeding 135kgNha−1 applied at pre-sowing, 67.5–90kgNha−1 at the initiation of stem elongation, and appropriate rates depending on the seedling growth at 5-leaf stage were optimum N fertilizer strategies to achieve high production for the direct sown winter oilseed rape in Yangtze River Basin.

Quantification of Plasmodiophora brassicae Using a DNA-Based Soil Test Facilitates Sustainable Oilseed Rape Production.

Outbreaks of clubroot disease caused by the soil-borne obligate parasite Plasmodiophora brassicae are common in oilseed rape (OSR) in Sweden. A DNA-based soil testing service that identifies fields where P. brassicae poses a significant risk of clubroot infection is now commercially available. It was applied here in field surveys to monitor the prevalence of P. brassicae DNA in field soils intended for winter OSR production and winter OSR field experiments. In 2013 in Scania, prior to planting, P. brassicae DNA was detected in 60% of 45 fields on 10 of 18 farms. In 2014, P. brassicae DNA was detected in 44% of 59 fields in 14 of 36 farms, in the main winter OSR producing region in southern Sweden. P. brassicae was present indicative of a risk for >10% yield loss with susceptible cultivars (>1300 DNA copies g soil−1) in 47% and 44% of fields in 2013 and 2014 respectively. Furthermore, P. brassicae DNA was indicative of sites at risk of complete crop failure if susceptible cultivars were grown (>50 000 copies g−1 soil) in 14% and 8% of fields in 2013 and 2014, respectively. A survey of all fields at Lanna research station in western Sweden showed that P. brassicae was spread throughout the farm, as only three of the fields (20%) showed infection levels below the detection limit for P.brassicae DNA, while the level was >50,000 DNA copies g−1 soil in 20% of the fields. Soil-borne spread is of critical importance and soil scraped off footwear showed levels of up to 682 million spores g−1 soil. Soil testing is an important tool for determining the presence of P. brassicae and providing an indication of potential yield loss, e.g., in advisory work on planning for a sustainable OSR crop rotation. This soil test is gaining acceptance as a tool that increases the likelihood of success in precision agriculture and in applied research conducted in commercial oilseed fields and at research stations. The present application highlights the importance of prevention of disease spread by cleaning of farm equipment, footwear, etc.

Verticillium longisporum, the invisible threat to oilseed rape and other brassicaceous plant hosts.

The causal agents of Verticillium wilts are globally distributed pathogens that cause significant crop losses every year. Most Verticillium wilts are caused by V. dahliae, which is pathogenic on a broad range of plant hosts, whereas other pathogenic Verticillium species have more restricted host ranges. In contrast, V. longisporum appears to prefer brassicaceous plants and poses an increasing problem to oilseed rape production. Kingdom Fungi; Phylum Ascomycota; Class Sordariomycetes; Subclass Hypocreomycetida; Family Plectosphaerellaceae; genus Verticillium. Dark unilateral stripes appear on the stems of apparently healthy looking oilseed rape plants at the end of the growing season. Microsclerotia are subsequently formed in the stem cortex beneath the epidermis. Verticillium longisporum is the only non-haploid species in the Verticillium genus, as it is an amphidiploid hybrid that carries almost twice as much genetic material as the other Verticillium species as a result of interspecific hybridization. There is no effective fungicide treatment to control Verticillium diseases, and resistance breeding is the preferred strategy for disease management. However, only a few Verticillium wilt resistance genes have been identified, and monogenic resistance against V. longisporum has not yet been found. Quantitative resistance exists mainly in the Brassica C-genome of parental cabbage lines and may be introgressed in oilseed rape breeding lines. Oilseed rape colonized by V. longisporum does not develop wilting symptoms, and therefore the common name of Verticillium wilt is unsuitable for this crop. Therefore, we propose 'Verticillium stem striping' as the common name for Verticillium infections of oilseed rape.

Impacts of high intensity crop rotation and N management on oilseed rape productivity in Germany

A rotational field experiment was established in the year 2002 at the experimental farm Etzdorf in the Hercynian dry region of central Germany. Since 2005 field measured datasets were used to determine the effect of different preceding crop combinations and different nitrogen (N) fertilisation treatments on the seed yield, oil content, oil yield and N-use efficiency of oilseed rape (Brassica napus L.). The preceding crop combinations compared were winter wheat (Triticum aestivum L.)-winter wheat (WW), WW-oilseed rape (OSR), OSR-OSR and an OSR monoculture. In addition to the preceding crop combination, N fertiliser treatments with either 120 kg N ha–1 or 180 kg N ha–1 were established in the year 2013. Overall the results demonstrated that seed yield, oil yield and N-use efficiency all declined with an increased cropping intensity for the period 2005–2012. Higher N rates in the 2013–2014 seasons increased seed yield and oil yield when OSR followed WW-WW pre-crops. OSR monoculture had lowest yield independent of applied N. Seed yield declined from 4.61 t ha–1 (OSR following WW-WW) to 4.28 t ha–1 in the OSR monoculture with 120 kg N ha–1, and from 4.81 t ha–1 (following WW-WW) to 4.42 t ha–1 in the OSR monoculture with 180 kg N ha–1. Higher N rates generally reduced N-use efficiency, with highest N-efficiency for WW-WW-OSR (38.4 kg kg–1), and lowest for continuous OSR receiving 180 kg N ha–1 (24.5 kg kg–1). These results emphasise the importance of crop rotation to maintain seed yield and oil yield of oilseed rape, and to maximise the response to applied N. A reduced N rate increased N-use efficiency and reduced the risk of high N surpluses without a significant/equivalent decrease of the seed yield when the rotation was optimised.

Achievements in NS rapeseed hybrids breeding

The increased production of oilseed rape (Brassica napus L.) is evident on a global scale, but also in Serbia in the last decade. Rapeseed is used primarily for vegetable oil and processing industry, but also as a source of protein for animal feed and green manure. Following the cultivation of varieties, breeding and cultivation of hybrid rapeseed started in the 1990's, to take advantage of heterosis in F1 generation, while protecting the breeder's rights during seed commercialization. The breeding of hybrid oilseed rape requires high quality starting material (lines with good combining abilities) for introduction of male sterility. Ogura sterility system is primarily used at the Institute of Field and Vegetable Crops, Novi Sad, Serbia. To use this system, separate lines are modified with genes for cytoplasmic male sterility (cms female line - mother line) and restoration of fertility (Rf male lines - father line). In order to maintain the sterility of the mother line it is necessary to produce a maintainer line of cytoplasmic male sterility. Creation of these lines and hybrids at the Institute of Field and Vegetable Crops was successfully monitored with intense use of cytogenetic laboratory methods. The structure and vitality of pollen, including different phases during meiosis were checked so that cms stability was confirmed during the introduction of these genes into different lines. Rapeseed breeding program in Serbia resulted in numerous varieties through collaboration of researchers engaged in breeding and genetics of this plant species. So far, in addition to 12 varieties of winter rapeseed and two varieties of spring rapeseed, a new hybrid of winter rapeseed NS Ras was registered in Serbia. NS Ras is an early-maturing hybrid characterized by high seed yield and oil content. Average yield of NS Ras for two seasons and three sites was 4256 kg ha-1 of seed and 1704 kg ha-1 of oil. Three promising winter rapeseed hybrids are in the process of registration in the Republic of Serbia and one in the EU. While addressing many challenges in breeding, especially resistance to biotic and abiotic stress, in addition to classical breeding, it is necessary to apply the cytogenetic and molecular analysis to increase the efficiency of producing competitive rapeseed genotypes.

Factors of the Development of Oilseed Rape Production in Poland on the Background of the World

Factors of the Development of Oilseed Rape Production in Poland on the Background of the World

Determinants of nectar production in oilseed rape

With the aim of contributing to the development of models forecasting the melliferous characteristics and the potential honey yield of oilseed rape, we analyzed data on the temporal pattern of number of oilseed rape flowers, nectar secretion, sugar concentration, and weight of bee hives in relation to meteorological parameters, across three seasons of oilseed rape production in Denmark. The analyses showed that the time of flowering of oilseed rape is governed by degree days, while the number of flowers at the onset of flowering is determined by the preceding climatic conditions, with long frost-free periods in the beginning of a year (January–March) leading to the setting of more flowers. On the other hand, the decrease in the number of open oilseed rape flowers during the flowering period seems to be governed exclusively by inherent characteristics of oilseed rape. A late flowering in 2013 was associated with significantly reduced quality of the nectar in terms of both volume and sugar concentration, and our results suggest that the oilseed rape in this year did not contribute notably to bee colony development. In years in which the oilseed rape flowered around the normal time (beginning of May), the amount of secreted sugar decreased over the flowering period, being governed by inherent oilseed rape characteristics modified by climatic factors preceding the onset of flowering, as well as climatic conditions during flowering. The exploitation of oilseed rape nectar by bee colonies was found to be influenced by the amount of secreted sugar, as well as by the temperature conditions and the strength of the colony during flowering. Our results will assist beekeepers in predicting nectar production and sugar yield in oilseed rape and the ability of bees to exploit the sugar.

Use of formulated Trichoderma sp. Tri-1 in combination with reduced rates of chemical pesticide for control of Sclerotinia sclerotiorium on oilseed rape

Sustainable strategies for control of Sclerotinia sclerotiorum on oilseed rape are needed. Here we tested combinations of Trichoderma sp. Tri-1, formulated with oilseed rape seedcake and straw, with reduced application rates of the recommended chemical pesticide carbendazim for control of this pathogen on oilseed rape. The treatment containing the recommended rate of carbendazim provided the greatest reduction in disease when compared with treatments containing individual applications of lower rates of this pesticide or the formulated Tri-1 treatment in all field experiments. Treatments containing formulated Tri-1 combined with carbendazim applied at 50% or 75% the recommended rate reduced incidence of disease to levels statistically similar to the treatment containing carbendazim applied at the recommended rate in two field experiments conducted at the Wuxue County field site where a rice-oilseed rape rotation was used. The treatment containing formulated Tri-1 combined with carbendazim applied at 75% the recommended rate reduced incidence of disease to levels statistically similar to the treatment containing carbendazim applied at the recommended rate in two field experiments conducted at the Wuhan field site where a soybean-oilseed rape rotation was used. Experiments reported here using two oilseed rape production rotations indicate that integration of a biologically based control tactic, such as formulated Tri-1, into a disease management strategy can increase oilseed rape production sustainability through reduction in the use of chemical pesticides.

Complementary diversity for nitrogen uptake and utilisation efficiency reveals broad potential for increased sustainability of oilseed rape production

Nitrogen use efficiency (NUE) has become a major global megatrend for sustainable agricultural production, particularly in association with the reduced release of nitrogen-derived greenhouse gases from soils and nitrate contamination of waterways. Oilseed rape (Brassica napus L.), the second most important oilseed crop worldwide, requires relatively high N fertilisation but releases an N balance surplus after harvest. The use of genetic variation to breed more efficient varieties is a promising option to improve agricultural sustainability. We assessed 30 diverse winter oilseed rape accessions at contrasting nitrogen fertilisation levels for 33 physiological traits associated with N uptake and utilisation efficiency. Relationships among traits across the diversity panel were used to identify key complementary factors contributing to overall NUE. Trait correlations revealed considerable variation for NUE parameters, including positive effects of early flowering and high leaf N concentration on enhanced N utilisation under low N input. Furthermore, seed yield per se was found to be more important than the seed N concentration for simultaneously achieving both high N utilisation and reduced N balance surplus. Independent inheritance of N uptake and N utilisation traits suggests potential for further improvement of NUE in oilseed rape by targeted combination of contributing factors in new, high-yielding varieties.

FACTORS OF DEVELOPMENT OF HOLDINGS ENGAGED IN OILSEED RAPE PRODUCTION IN THE OPINION OF THEIR OWNERS

The aim of the study was to investigate and evaluate the development factors of farms engaged in oilseed rape production. The study used primary data from studies conducted its own in 2014 on a group of 73 households selected in a targeted manner. The study divided community because of the surface rape for the following groups: up to 10 hectares (20 households), 11-20 hectares (20 households), 21-30 hectares (13 households), 31-40 hectares (9 farms) and the area. 40 hectares (11 households). The study used survey method using a questionnaire interview. The research shows that in the development of farms engaged in the growing of rape the important meaning have EU policies for biofuels and the possibility of the use of funds under the RDP. The research shows that the most important opportunity are low-interest loans and funds from the EU. Among the barriers to farmers in the largest number of cases is a high demand for land and a small supply of land, which is strongly linked with the cultivation of oilseed rape.

BnSGS3 Has Differential Effects on the Accumulation of CMV, ORMV and TuMV in Oilseed Rape.

Virus diseases greatly affect oilseed rape (Brassica napus) production. Investigating antiviral genes may lead to the development of disease-resistant varieties of oilseed rape. In this study, we examined the effects of the suppressor of gene silencing 3 in Brassica napus (BnSGS3, a putative antiviral gene) with different genus viruses by constructing BnSGS3-overexpressing (BnSGS3-Ov) and BnSGS3-silenced (BnSGS3-Si) oilseed rape (cv. Zhongshuang No. 6) plants. These three viruses are Oilseed rape mosaic virus (ORMV), Turnip mosaic virus (TuMV) and Cucumber mosaic virus (CMV). The native BnSGS3 expressed in all examined tissues with the highest expression in siliques. All three viruses induced BnSGS3 expression, but ORMV induced a dramatic increase in the BnSGS3-Ov plants, followed by TuMV and CMV. Upon inoculation with three different viruses, transcript abundance of BnSGS3 gene follows: BnSGS3-Ov > non-transgenic plants > BnSGS3-Si. The accumulation quantities of ORMV and TuMV exhibited a similar trend. However, CMV accumulation showed an opposite trend where virus accumulations were negatively correlated with BnSGS3 expression. The results suggest that BnSGS3 selectively inhibits CMV accumulation but promotes ORMV and TuMV accumulation. BnSGS3 should be used in different ways (up- and down-regulation) for breeding virus-resistant oilseed rape varieties.

Physiological and molecular analyses of black and yellow seeded Brassica napus regulated by 5-aminolivulinic acid under chromium stress

Brassica napus L. is a promising oilseed crop among the oil producing species. So, it is prime concern to screen the metal tolerant genotypes in order to increase the oilseed rape production through the utilization of pollutant soil regimes. Nowadays, use of plant growth regulators against abiotic stress is one of the major objectives of researchers. In this study, an attempt was carried out to analyze the pivotal role of exogenously applied 5-amenolevulinic acid (ALA) on alleviating chromium (Cr)-toxicity in black and yellow seeded B. napus. Plants of two cultivars (ZS 758 – a black seed type, and Zheda 622 – a yellow seed type) were treated with 400 μM Cr with or without 15 and 30 mg/L ALA. Results showed that exogenously applied ALA improved the plant growth and increased ALA contents; however, it decreased the Cr concentration in B. napus leaves under Cr-toxicity. Moreover, exogenous ALA reduced oxidative stress by up-regulating antioxidant enzyme activities and their related gene expression. Further, results suggested that stress responsive protein's transcript level such as HSP90-1 and MT-1 were increased under Cr stress alone in both cultivars. Exogenously applied ALA further enhanced the expression rate in both genotypes and obviously results were found in favor of cultivar ZS 758. The ultrastructural changes were observed more obvious in yellow seeded than black seeded cultivar; however, exogenously applied ALA helped the plants to recover their cell turgidity under Cr stress. The present study describes a detailed molecular mechanism how ALA regulates the plant growth by improving antioxidant machinery and related transcript levels, cellular modification as well as stress related genes expression under Cr-toxicity.

Crop modelling based analysis of site-specific production limitations of winter oilseed rape in northern Germany

Winter oilseed rape production is typically characterised by low nitrogen (N) use efficiency. Defining site-specific fertiliser strategies based on field trials and crop modelling may help to improve the ecological efficiency of this crop. However, no model has been evaluated for winter oilseed rape that simulates the growth of the plant as limited by the interaction of water and N. In this study, the APSIM canola model which was originally developed for the temperate regions of Australia, was adapted for conditions in Germany and tested against measured data (total biomass, grain yield, leaf area index, N-uptake and soil mineral N) at three sites near Göttingen (northern Germany). In the second part of the study, the evaluated model was used in a simulation experiment to explore site-specific climate and soil related production limitations to match fertiliser rates to yield targets. Historical weather data from four sites across northern Germany and a fertile loamy soil with different rooting depths, implicating different plant available water capacities, were used. Model results showed large differences in yield (up to 1000kgha−1) and N-balance (>30kgha−1) for 200kg N-fertiliser rate ha−1 between restricted (50cm) and unrestricted rooting depths. Simulated yields for such high N-fertiliser rate were lower for sites with continental climate than for sites close to the coast, reflecting different rainfall patterns. Results indicate that water supply plays a critical role when maintaining high N use efficiency and reaching simultaneously grain yields of 4000kgha−1.

Estimating nutrient requirements for winter oilseed rape based on QUEFTS analysis

SUMMARYEstimating crop nutrient requirements for winter oilseed rape (Brassica napus L.) is a crucial step in optimizing fertilization to enhance seed yield and improve fertilizer use efficiency. In the present paper, a database composed of 1035 on-farm observations collected from 2005 to 2010 across the major winter oilseed rape production regions in China was used to evaluate internal nutrient efficiencies (kg seed per kg nutrient in plant dry matter); then the Quantitative Evaluation of the Fertility of Tropical Soils (QUEFTS) model for winter oilseed rape was developed to describe the nutrient uptake-yield relationship of oilseed rape over a wide range of environmental conditions and predict the nutrient requirements for a target yield. After excluding observations with low harvest index values, <0·20, and excluding 0·025 of the highest and lowest internal nutrient efficiencies, the minimum and maximum internal nutrient efficiencies were estimated as 13·1 and 31·6 kg seed/kg nitrogen (N), 68·9 and 200·3 kg seed/kg phosphorus (P) and 8·9 and 31·1 kg seed/kg potassium (K), respectively. On the basis of the data settings, the balanced N, P and K uptake at different yield potential levels was calculated using a linear–parabolic–plateau curve with the QUEFTS model. Crop nutrient requirements increased linearly until the yield reached approximately 0·60–0·70 of the potential yield, and 46·0 kg N, 8·0 kg P and 57·1 kg K were found to be needed to produce 1000 kg of seed. The corresponding internal nutrient efficiencies were 21·8, 125·1 and 17·5 kg seed/kg N, P and K, respectively. However, when the target yields approached the yield potential, a decrease in internal nutrient efficiencies was detected in the model. The predicted nutrient requirement values simulated by the QUEFTS model compared well with observed values across a range of conditions. To conclude, the QUEFTS model was shown to be a practical and robust tool for assessing the crop nutrient requirements of winter oilseed rape.

On-farm trials of optimal fertilizer recommendations for the maintenance of high seed yields in winter oilseed rape (Brassica napus L.) production

Mineral fertilizer plays an important role in the maintenance of high rapeseed yields during oilseed rape (Brassica napus L.) production. On-farm experiments at 60 sites throughout the Yangtze River Basin in China were conducted for 2 years to evaluate the effects of the recommended fertilization rates (180 kg N ha−1, 90 kg P2O5 ha−1, and 120 kg K2O ha−1) on the rapeseed yield, and three indices of soil nutrient supply were adopted to estimate the yield responses to fertilizer recommendation. The results showed that the average contributions of nitrogen (N), phosphorus (P) and potassium (K) fertilizer to seed yield were 40.4, 23.1 and 11.5%, respectively. Compared with the farmers’ fertilization practices (FFP), the recommended fertilization significantly enhanced the seed yield by 29.1% on average. The relationships between plant-available soil nutrient supply, seed yields of the nutrient omission treatments and the yield responses to fertilization were significant, rather than the results of soil testing. With plant-available soil nutrient supplies and seed yields increasing, the yield responses and fertilizer use efficiencies decreased. When the seed yields of no-N and no-P treatments were less than 2000 kg ha−1 and 1500 kg ha−1, the recommended fertilizer rate was beneficial for achieving high seed yield and high efficiency. As defined in our study, the recommended fertilization rates could be used as the regional mean optimal rates (RMOR) of fertilization for winter oilseed rape in the Yangtze River Basin. Partial adjustments according to crop nutrient uptakes and seed yields of the nutrient omission treatments will be feasible for the sites where they were nonresponsive to RMOR.

Arable Crop Disease Control, Environmental Change and Food Security

Crop diseases cause yield losses, yet crop productivity needs to increase by > 70% over the next 35 years to accommodate population growth and changing dietary preferences1. Crop plants and pathogens interact in response to changes in environmental conditions. Recent predictions made by combining climate model data with an oilseed rape growth model and a phoma stem canker model suggest that yield will increase in the UK, especially in Scotland, whereas potential losses from phoma stem canker will be greatest in southern England2. Oilseed rape production in China is threatened by the possible arrival of Leptosphaeria maculans, a more virulent causal agent of phoma stem canker than the existing species Leptosphaeria biglobosa3. A strong correlation found between sulphur dioxide concentration and the ratio of Phaeosphaeria nodorum to Zymoseptoria graminicola in archived wheat samples at Rothamsted Research (1844 to date) suggests that subtle environmental changes can also cause changes in pathogen populations4. Ensuring future food security under environmental change is challenging and will require increased understanding of in planta disease processes. Effector-triggered defence (ETD) operates against extracellular fungal pathogens by R gene-encoded cell surface receptor-like proteins that trigger cell death only after a period of endophytic pathogen growth5. An example of this is resistance in oilseed rape against Pyrenopeziza brassicae that operates by preventing asexual sporulation. Exploiting such understanding and developing strategies to control biotic stressors are important to ensure adequate food supply for the future6.

Exploring Climatic Impact on Oilseed Rape Yield in Switzerland

Climate plays an important role in agriculture. Crops are submitted to various stresses such as water stress, heat stress, frost, that may decrease yield or quality. The aim of this work was to determine the most important climatic limiting factors of oilseed rape yield in Switzerland.The approach consisted in determining, based on a literature review, several climate indices known to affect different phases of oilseed rape growth. Four phases were calculated dynamically based on Habekotté (1997) phenology model. For each phase, response functions to climatic indices were pre-defined based on literature- and expert-knowledge and automatically refined based on observed data. A different weight was attributed to each phase in order to account for compensating effects over the development cycle. The approach was applied for oilseed rape (Brassica napus L.) production in Switzerland. Comparison with independent yield data showed a good agreement of estimated crop-specific climatic suitability with scaled yields.The chosen indices were maximum temperature, minimum temperature, photothermal quotient, length of the phase and water availability. The calculation of phase weight showed that the flowering phase was the most sensitive to climatic stresses, followed by seed filling (anthesis to maturity phase). Analysis of climatic limitations on two locations in Switzerland showed that a low radiation, resulting in low photothermal quotient was the most important limiting factor for both phases, with more impact during flowering. Within Switzerland, greater differences appeared among years than among locations.Further possible applications of this work could be either to map best climatic areas for oilseed rape growth, or even to adapt variety choice to regional climatic limitations.

Genetic diversity and differentiation of Leptosphaeria biglobosa on oilseed rape in China

Phoma stem canker (blackleg), caused by the fungi Leptosphaeria maculans and L. biglobosa, is the most devastating disease in oilseed rape (canola) production worldwide. In this study, 84 Leptosphaeria isolates were collected in China from rapeseed (Brassica napus) plants with blackleg symptoms and identified using multiplex PCR and rDNA-ITS sequence analysis. Results showed that all these isolates are L. biglobosa and no L. maculans was detected. A total of 99 isolates was analyzed, including 15 other L. biglobosa isolates from the UK, Canada and Poland using rDNA-ITS sequences, and all isolates were found to belong to the L. biglobosa 'brassicae' subclade. The genetic variation of these 99 isolates was tested using ISSR (inter simple sequence repeats) markers using 24 polymorphic primers pairs that generated 241 bands by ISSR-PCR amplification. A dendrogram based on weighted pair group mean analysis of these bands revealed that L. biglobosa isolates from China clustered into different groups from those obtained from Canada and Europe. Furthermore, Chinese isolates from seven provinces, except those from Jiangsu, could be placed within the same cluster, based on geographical location. Nei’s gene diversity ranged from 0.25 in Jiangsu to 0.11 in Sichuan, and Shannon’s information index from 0.16 to 0.37. Genetic identity ranged from 0.784 to 0.834 when isolates from China were compared with those from Canada and the UK, respectively. Analysis of gene flow among populations (Nm) indicated that almost no gene exchange has occurred between L. biglobosa in China and the populations of the fungus from the UK or Canada.