Yield Of Winter Oilseed Rape Research Articles

Envirotyping within a multi-environment trial allowed identifying genetic determinants of winter oilseed rape yield stability

Key messageA comprehensive environmental characterization allowed identifying stable and interactive QTL for seed yield: QA09 and QC09a were detected across environments; whereas QA07a was specifically detected on the most stressed environments.A main challenge for rapeseed consists in maintaining seed yield while adapting to climate changes and contributing to environmental-friendly cropping systems. Breeding for cultivar adaptation is one of the keys to meet this challenge. Therefore, we propose to identify the genetic determinant of seed yield stability for winter oilseed rape using GWAS coupled with a multi-environmental trial and to interpret them in the light of environmental characteristics. Due to a comprehensive characterization of a multi-environmental trial using 79 indicators, four contrasting envirotypes were defined and used to identify interactive and stable seed yield QTL. A total of four QTLs were detected, among which, QA09 and QC09a, were stable (detected at the multi-environmental trial scale or for different envirotypes and environments); and one, QA07a, was specifically detected into the most stressed envirotype. The analysis of the molecular diversity at QA07a showed a lack of genetic diversity within modern lines compared to older cultivars bred before the selection for low glucosinolate content. The results were discussed in comparison with other studies and methods as well as in the context of breeding programs.

A synthesis‐analysis of winter oilseed rape yield response to planting density under intensive cropping system in Yangtze River Basin

AbstractOptimal yield is dependent on the collocations between plant population and individual growth. High plant population for direct‐sown winter oilseed rape would be a common method to achieve high yield under intensive cropping systems. We investigated the oilseed rape (Brassica napus L.) yield response to planting density while considering the productivity environment, nitrogen (N) fertilizer, and sowing date. A synthesis‐analysis was conducted by collecting the density–yield data in the field experiments of oilseed rape from 2000 to 2019 in China. The population yield response to different planting density levels could be described by a quadratic model, with a threshold value of 45–60 plants m−2. High planting density had no remarkable influence on the attainable population yield due to the decreasing individual potential yield. The population yield increment capacity by the increasing planting density was higher in medium yield environment (i.e., average yield at 1500–2500 kg ha−1). The planting density presented a remarkable effect on population yield after the N limitation was relieved. Increasing planting density at 104 plants per hectare was equivalent to applying 1.17 kg N fertilizer on population yield, ranging from 0.42 to 4.76 kg under different yield environment levels. Yield loss caused by unsuitable sowing date (especially for the late sowing) could be compensated by increasing planting density. Planting density played a crucial role in adapting other management practices. Optimizing the allocation of plant population and individual growth, and establishing target plant phenotype under high planting density would help achieve high population yield.

Yield of Winter Oilseed Rape (Brassica napus L. var. napus) in a Short-Term Monoculture and the Macronutrient Accumulation in Relation to the Dose and Method of Sulphur Application

The objective of this study was to assess the yield efficiency of sulphur-enhanced fertilisers, depending on the dose and application method, in a short-lived (three-year) monoculture of winter oilseed rape under the climate and soil conditions of south-eastern Poland. The experiment was carried out between 2010 and 2013 on winter oilseed rape (Brassica napus L. var. napus) of the Orlando variety, fertilised with different sulphur doses—0, 20, 40 or 60 kg S ha−1 applied in different method—soil application sowing, foliar application in the spring, and soil application sowing + foliar application in the spring (combined application). Following the harvest, seed and straw yields and the content of macroelements (N, S, P, K, Ca and Mg) in the seed and straw samples were determined. The harvest indices were also established for each of these elements. The impact of sulphur on winter oilseed rape yield depended significantly on both the dose and the application method. Even at the lowest dose (20 kg·ha−1), sulphur materially increased seed yield, regardless of the application method. With autumn soil application and foliar application, differences between the lowest dose and the higher doses (40 and 60 kg·ha−1) were not significant. However, with combined application, the highest dose (60 kg·ha−1) significantly increased yield compared to the lower doses. In general, all the fertilisation approaches significantly increased the N, P, K, Ca and Mg contents compared to the control sample, but the differences between them were not substantial. Each of the sulphur application approaches decreased the harvest index for sulphur. The foliar application of each of the doses decreased the harvest indices for N, P, K and Ca. The soil application of 20 kg·ha−1, and the mixed application of 40 and 60 kg·ha−1, all increased the harvest indices for P, K and Ca.

Impact of different tillage on soil physical properties, CO2 emissions and winter oilseed rape yield

The investigation presents data on winter rape agrocenosis productivity, soil physical properties, and CO2 metabolism intensity using different tillages. The object of the research is the winter rape (Brassica napus L.) crop using different tillages. The aim of the study was to determine and compare the effects of different tillages and direct sowing on winter oilseed rape, soil physical properties and CO2 emissions. Methods of analysis. The studies have been carried out in accordance with established procedures. The methods used to apply the Stationary Single Factor Field Experiment were installed at the Vytautas Magnus University Experimental Station in 1988. The study factor is tillage systems: normal deep pruning at a depth of 23–25 cm in autumn (DP), control; shallow pruning at a depth of 12 to 15 cm in autumn (SP); deep loosening at a depth of 8 to 10 cm in autumn (DL); shallow loosening 13–25 cm (SL); direct seeding with cultivation up to 5 cm (NT). Results. For a long time, direct seeding into the stubble (with cultivation up to 5 cm) increases the resistance of the soil shear. During the whole investigation period, a lower CO2 concentration was observed in shallow loosening and direct seeding fields. Simplified tillages did not have a significant impact on the yields of winter rape.

Farmers’ perspectives of future management of winter oilseed rape (Brassica napus L.): A case study from north-eastern Germany

Recent analysis of European on-farm data revealed yield instability for winter oilseed rape (WOSR). To better facilitate farmers, the main participants in agriculture, it is of vital importance to interpret how the fluctuation in crop yields and other potential factors may influence farmers’ perspectives and decision-making in the future. However, few studies have explored this aspect.This research aims to focus on farmers′ concerns and anticipated behaviour adjustments for future WOSR production. By using a case study in north-eastern Germany, an online farmer survey was developed to explore the situation regarding past and future production and management of European WOSR.One of the most interesting findings is that the farmer participants anticipated to grow a smaller share of WOSR in the future with a one-year longer rotation gap. Crop yields was suggested to be a major factor influencing this decision change.Farmers are concerned about the future infestation risks of insect pests and fungal diseases in WOSR, thus they expressed potential related adjustments in crop varieties (Turnip yellows virus and clubroot resistant cultivars) and management strategies (e.g., increase insecticide use, adjust rotation rotations). Their behaviours were also highly influenced by the regulation changes at European and national levels, especially regarding glyphosate and fertilizer restrictions. Potential future weather extremes caused by climate changes are also of concerns to farmers.This study helps provide indications for future WOSR production in Europe. However, the findings about farmers’ behavioural inclinations due to WOSR yield instability, regulation adjustments and environmental changes may also be useful for other regions globally that have similar conditions.

Model sensitivity of simulated yield of winter oilseed rape to climate change scenarios in Europe

Winter oilseed rape (WOSR) is Europe’s prime oilseed crop and is grown for biofuel and edible oil production. To investigate the effects of climate change on the yield of winter oilseed rape, two crop models (HERMES and HUME-OSR) were used. This study investigated the sensitivity of crop model parameters (as a proxy of plant traits) under climate change. For both models, a global sensitivity analysis was performed under current temperatures, an increase of 2 and 4 °C, in combination with −50 %, −25 %, current, +25 % and +50 % precipitation change, resulting in 15 combinations. The analysis was done for six different sites in Europe located in Germany, France, and the Czech Republic. The two models differ in model formalism; however, results show that the most sensitive parameters of WOSR for both models are associated with drought, both under current climatic conditions, and under changing temperatures and precipitation regimes. The sensitivity analysis shows that the most sensitive parameters for WOSR yield under climate change relate to plant traits affecting the growth of the vegetative phase.

The Effect of Meat and Bone Meal (MBM) on the Seed Yield and Quality of Winter Oilseed Rape

The aim of a two-year field experiment conducted in north-eastern (NE) Poland was to evaluate the effect of meat and bone meal (MBM) applied without or with mineral nitrogen (N) on seed yield, thousand seed weight (TSW), protein yield, fat yield, fatty acid profile and glucosinolate (GLS) concentrations in winter oilseed rape. Five treatments were compared: MBM applied at 1.0, 1.5, 2.0 Mg ha−1, inorganic NPK, and a zero-N check. The first two MBM plots and the NPK plots received supplemental inorganic N to provide a total of 158 kg N ha−1. The yields of winter oilseed rape were highest in the treatment with mineral (NPK) fertilization. All plots receiving MBM yielded equally to each other but greater than the unfertilized check. Winter oilseed rape accumulated significantly more protein in seeds in the NPK treatment than in the 1.5 Mg ha−1 MBM + 40 kg N ha−1 treatment. The crude fat content of seeds was significantly higher in the 1.5 Mg MBM ha−1 + 40 kg N ha−1 treatment, compared with the NPK treatment and the 1.0 Mg MBM ha−1 + 79 kg N ha−1 treatment. Oleic, linoleic, and α-linolenic acids accounted for nearly 90% of total fatty acids in rapeseed oil, and the average ratio of linoleic acid to α-linolenic acid was 1.81:1. Fertilization had a minor influence on the proportions of fatty acids, which were considerably affected by adverse weather conditions.

Analysis of Changes in Soil Organic Carbon, Energy Consumption and Environmental Impact Using Bio-Products in the Production of Winter Wheat and Oilseed Rape

Agricultural management, environmentally friendly technologies, chemical, organic and bio-based substances used, as well as meteorological factors, have a significant impact on the fluctuations of soil organic carbon (SOC). The aim of this research was to analyze the effect of different biopreparations on the changes of SOC content and the winter wheat and winter oilseed rape yields by assessing the energy consumption efficiency and the environmental impacts. The experimental research was conducted from 2017 to 2019 in three different treatments, in two of which were used either a molasses and magnesium sulphate based-biopreparation (T1) or a bacteria-based biopreparation (T2), while treatment T3 was applied as a control where no biopreparations were used. The dynamics of SOC content were analyzed at two depths: 0–10 and 10–20 cm. For the analysis of energy efficiency indicators and environmental impacts, the greenhouse gas (GHG) and energy consumption conversion equivalents were used. A summary of the results showed that both types of biopreparations had a positive effect on the changes of SOC content, which was especially evident in the deeper layers at 10–20 cm depth, where, irrespective of the crop type, a more significant increase of the SOC content was observed every year of the experiment compared to the control treatment. Biopreparations had a significant effect in increasing the winter wheat and winter oilseed rape yield. The best energy efficiency ratio was observed in winter wheat (4.84) and winter oilseed rape (5.11) in treatment T1. The results of the environmental impact assessment showed that the lowest GHG emissions were recorded in the winter wheat production in treatment T1 at 108.7–149.1 kg CO2eq Mg−1, while the highest were observed in oilseed rape production in the control treatment T3 at 343.4 kg CO2eq Mg−1.

Responses of Yield Fluctuation of Winter Oilseed Rape to Climate Anomalies in South China at Provincial Scale

The regional differences for responses of winter oilseed rape yield to climate changes was not reported in China, and the statistical climate–yield relationships at the provincial scale in south China should be a valuable attempt. With using provincial data of climate variables and oilseed rape yields during 1978–2016, the main findings were as follows: (1) based on 14 provincial climate-induced yield index (CIYI) series for oilseed rape yield, south China could be divided into five sub-regions with different temporal variations in CIYI by using principal component analysis, and they were Yangtze River delta (Region I), central south China (Region II), southwest China (Region III), southernmost China (Region IV) and southeastern coast (Region V), respectively; (2) the correlation and regression analysis between CIYI and monthly climate variables indicated that the precipitation of April, average potential evapotranspiration of November, average potential evapotranspiration of October, average mean temperature of May, and average potential evapotranspiration of September were the key climate variables (KCV) affecting yield in Region I, II, III, IV and V, respectively; (4) among the five sub-regions, the impacts of KCV changes on yields in southwest China were more notable, and the increasing trend of average potential evapotranspiration of November caused the decrease of yield by 2.08% in 1990s and 4.24% after 2000, respectively. These results could be employed as references for the assessment and mitigation of agro-meteorological disasters in south China.

Impact of winter oilseed rape nutritional status during vegetative growth on yield

The nutritional status of winter oilseed rape (WOSR) during its vegetative period is crucial for plant growth and can be used for the seed yield prediction. This hypothesis was verified based on the data from long-term field experiments. The experiment consisted of four potassium (K) treatments based on the progressive K supply potential to plants from soil and fertilizer and two magnesium treatments (–Mg, +Mg) conducted in 2013–2015. The content of nutrients (N<sub>tot</sub>, P, K, Mg, Ca, Fe, Mn, Zn, Cu) was determined at the rosette stage (BBCH 30) for leaves and separately for leaves and stems in the late stage of inflorescence growth (BBCH 57–59). The low K content appeared as the key limiting nutrient in WOSR plants in the rosette stage due to the insufficient soil fertility level, depended even more on weather conditions. This negative K nutritional trait persisted through the whole vegetative WOSR growth. Its detection was possible, because stems were included in the diagnostic procedure. The most reliable prognosis of WOSR yield was conducted based on the nutritional status of stems in the late stage of the inflorescence development.

Soil Extracellular Enzyme Activities and Uptake of N by Oilseed Rape Depending on Fertilization and Seaweed Biostimulant Application

The present study has aimed at enhancing the insufficient knowledge of functional soil enzymes properties influenced by inorganic fertilization and biostimulant application to increase the uptake of nitrogen affecting the winter oilseed rape yield. Field experiments were conducted in Poland (53° N, 18° E) in Alfisol (USDA). In this experiment, the NPK rates applied were as follows: high 180 N, 70 P and 160 K 132 N (kg ha−1) or low 144 N, 35 P and 66 K (kg ha−1); fertilization with elemental S 36 or 0 (kg ha−1); and the seaweed biostimulant Kelpak was applied or there was no such treatment. Due to low NPK fertilization rates, the activity of dehydrogenases, peroxidases, and catalase increased in subsistent generative development stages from flowering to ripening. At the ripening stage, the activity of these enzymes, as well as nitroreductase activity, were inhibited by high NPK fertilizer rates. The seaweed biostimulant application and S fertilization increased N accumulation in plants of oilseed rape in generative development, by 16% and 13%, respectively, as compared with the lack of these treatments. The application of S increased the uptake of nitrogen in shoots and in whole oilseed rape plants only after application of higher rates of NPK.

Yield instability of winter oilseed rape modulated by early winter temperature

Yield stability is a major problem in oilseed rape with inter-annual variation accounting for between 30–50% of the crop value among the major global rapeseed producers. The United Kingdom has persistent problems with yield instability, but the underlying causes remain unclear. We tested whether temperature plays a role in UK winter oilseed rape (WOSR) yield variation through analysis of aggregated country-wide on-farm yield data and in annual Recommended List variety trial data run by the UK Agriculture and Horticulture Development Board (AHDB). Our analyses of the two independent datasets both show that mean temperature in early winter is strongly and uniquely linked to variation in WOSR yield, with a rise in mean temperature of 1 °C associated with an average reduction of 113 (+−21) kg ha−1 in yield. We propose that understanding the mechanism by which early winter chilling affects WOSR yield will enable the breeding of varieties with a more stable and resilient yield in Western Europe as climatic variation increases.

Quantifying the effect of temporal variability of agro-meteorological disasters on winter oilseed rape yield: a case study in Jiangsu province, southeast China.

To address the increasing hazards of climate change to winter oilseed rape production in Jiangsu province, southeast China, a total of 12 agro-meteorological disaster indices (MDI) during 1961-2012 was applied to quantify the disaster impacts of spring precipitation extremes, autumn droughts, winter freezing injuries, and spring chilling injuries. The main findings were as follows: (1) due to the obvious north-south gradient of MDI, this province was classified as four climactic sub-regions: north, central-north, central-south, and south Jiangsu, respectively; (2) in central-north, central-south, and south Jiangsu, the maximum length of dry spell during autumn (DI3), the maximum duration of consecutive rainfalls during spring (PI3), and number of rainy days during spring (PI1) were selected as the leading MDI affecting oilseed rape yield, respectively; (3) each 1d of DI3, PI3, and PI1 increase would result in yield losses of 0.7%, 3.6%, and 1.7% in central-north, central-south, and south Jiangsu, respectively; (4) compared to the weak changes in spring rainfall and autumn drought, the significant weakening of winter-spring cold extremes across Jiangsu had more notable yield increasing effects, especially the strong decrease of freezing events during winter had increased yield by up to 1.4-3.0%.

Influence of crop management on formation of yield components of winter oilseed rape

The habitus of oilseed rape and its yield component values can be strongly affected by the structure of its stand. Field experiments took place in Central Bohemia in years 2013–2015 aiming at determining the influence of row-spacing (12.5, 25, 35 and 45 cm) on the yield components. Chosen parameters (the number of plants per unit area, the number of pods per plant, the number of seeds per pod and yield) were evaluated at the monitored stands (30 seeds/m<sup>2</sup> sowing rate, cv. DK Exquisite). The study confirmed the statistical significance of the influence of row-spacing on some winter oilseed rape yield components. Widening of the row-spacing has led to a decrease in the number of pods per plant and the number of plants per unit area and an increase in the number of seeds per pod parameter. 1000 seed weight was not affected. This study did not confirm a positive effect of sowing oilseed rape in rows wider than 12.5 cm. Therefore, such an agronomical decision cannot be recommended as a way to achieve higher seed yield.

Evaluating agroclimatic constraints and yield gaps for winter oilseed rape (Brassica napus L.) \u2013 A case study

Evaluating the effects of agroclimatic constraints on winter oilseed rape (WOSR) yield can facilitate the development of agricultural mitigation and adaptation strategies. In this study, we investigated the relationship between the WOSR yield and agroclimatic factors using the yield data collected from Agricultural Yearbook and field experimental sites, and the climate dataset from the meteorological stations in Hubei province, China. Five agroclimatic indicators during WOSR growth, such as ≥0 °C accumulated temperature (AT-0), overwintering days (OWD), precipitation (P), precipitation at an earlier stage (EP) and sunshine hours (S), were extracted from twelve agroclimatic indices. The attainable yield for the five yield-limiting factors ranged from 2638 kg ha−1 (EP) to 3089 kg ha−1 (AT-0). Farmers (Yfarm) and local agronomists (Yexp) have achieved 63% and 86% of the attainable yield (Yatt), respectively. The contribution of optimum fertilization to narrow the yield gap (NYexp) was 52% for the factor P, which was remarkably lower than the mean value (63%). Overall, the precipitation was the crucial yield-limiting agroclimatic factor, and restricted the effect of optimizing fertilization. The integrated data suggest that agricultural strategies of mitigation and adaptation to climatic variability based on different agroclimatic factors are essential for improving the crop yield.

Sowing Date and Rate Effect on Winter Oilseed Rape (Brassica napus L.) Yield Components’ Formation

Abstract Crop yield per area is the product of plant density and productivity of an individual plant. Plant density and the time of winter oilseed rape sowing influences yield components (parameters of individual plant productivity), such as pod number per plant, seed number per pod, plant productivity, seed weight, and plant branching. The aim of this three-year (2008–2010) study was to investigate winter oilseed rape yield components depending on sowing date (five sowing dates) and sowing rate (four sowing rates for each variety) as initial cause of plant density at harvest for two type winter oilseed rape varieties (open pollinated ‘Californium’ and hybrid ‘Excalibur’). Field trials were carried out at the Research and Study Farm “Vecauce” of the Latvia University of Agriculture. Winter oilseed rape yield components (pod number per plant and seed number per pod, plant productivity (seed number per plant and plant productivity in g) as well as the number of primary branches per plant) were affected (p < 0.05) by sowing date and rate for both varieties. In general, no significant effect of sowing rate on 1000-seed weight was observed (p > 0.05), but sowing date influenced this component significantly (p < 0.05). A yield compensation mechanism was demonstrated by significant (p < 0.05) negative correlations between plant density at harvest and parameters of individual plant productivity.

Comparison of regression techniques to predict response of oilseed rape yield to variation in climatic conditions in Denmark

Abstract Statistical regression models represent alternatives to process-based dynamic models for predicting the response of crop yields to variation in climatic conditions. Regression models can be used to quantify the effect of change in temperature and precipitation on yields. However, it is difficult to identify the most relevant input variables that should be included in regression models due to the high number of candidate variables and to their correlations. This paper compares several regression techniques for modeling response of winter oilseed rape yield to a high number of correlated input variables. Several statistical regression methods were fitted to a dataset including 689 observations of winter oilseed rape yield from replicated field experiments conducted in 239 sites in Denmark, covering nearly all regions of the country from 1992 to 2013. Regression methods were compared by cross-validation. The regression methods leading to the most accurate yield predictions were Lasso and Elastic Net, and the least accurate methods were ordinary least squares and stepwise regression. Partial least squares and ridge regression methods gave intermediate results. The estimated relative yield change for a +1°C temperature increase during flowering was estimated to range between 0 and +6 %, depending on choice of regression method. Precipitation was found to have an adverse effect on yield during autumn and winter. It was estimated that an increase in precipitation of +1 mm/day would result in a relative yield change ranging from 0 to −4 %. Soil type was also important for crop yields with lower yields on sandy soils compared to loamy soils. Later sowing was found to result in increased crop yield. The estimated effect of climate on yield was highly sensitive to the chosen regression method. Regression models showing similar performance led in some cases to different conclusions with respect to effect of temperature and precipitation. Hence, it is recommended to apply an ensemble of regression models, in order to account for the sensitivity of the data driven models for projecting crop yield under climate change.

Analysis of yield and plant traits of oilseed rape (Brassica napus L.) cultivated in temperate region in light of the possibilities of sowing in arid areas

This work is a review of selected literature on the species of <em>Brassica</em> with the greatest economic significance. Oilseed rape (<em>Brassica napus</em> ssp. <em>oleifera</em>) currently ranks third worldwide among oilseed crops used for oil production and is the most important in the temperate zone. The manifold uses of rape include not only human consumption of oil, but also the use of post-extraction meal to feed livestock as well as industrial applications as a source of bioenergy or cellulose. The improvement in the economic position of rape among crop plants is also due to the doubling of its yield between 1970 and 2009; the average annual increase in seed yield worldwide was 27 kg ha<sup>−1</sup> yr<sup>−1</sup>. The yield level in Europe exceeds the average yields achieved in the world, particularly in Asia. Recently, the cultivation of oilseed rape was started on a relatively large acreage in Iran where the yield amounted 2.1 t ha<sup>−1</sup>, exceeding the yields of China and India. In Poland, the acreage of oilseed rape cultivation between 1965 and 2013 increased 3–4 times, and during this period the annual increase in seed yield was 29 kg ha<sup>−1</sup> yr<sup>−1</sup>. Under the field conditions of the temperate climate zone, winter oilseed rape yield is mainly determined by agro-climatic conditions during the growing period, the level of nitrogen fertilization, and the production potential of varieties, which is currently highest in hybrids. There is a noticeable tendency of hybrids towards formation of more siliques by individual oilseed plants. Different production categories of plants appear in a rape crop. Semi-dwarf varieties of winter rapeseed are distinguished by greater silique density, particularly on the main shoot. Moreover, these hybrids are characterized by faster growth of the root system, which enables them to take up nitrogen from the soil more efficiently.

Yield and mineral composition of seeds of leguminous plants and grain of spring wheat as well as their residual effect on the yield and chemical composition of winter oilseed rape seeds

A controlled field experiment was carried out in 2011-2014 in order to determine yields and chemical composition of selected genotypes of leguminous plants and spring wheat, as well as their value as a preceding crop (crop volume, mineral composition of seeds) for winter oilseed rape grown in Northern Poland. Chemical analysis of the content of macronutrients and micronutrients in seeds and grain was conducted using standard methods after mineralisation in H2SO4 with H2O2 as an oxidant (macronutrients), or in a mixture of the acids HNO3+HCl+HClO4 (micronutrients). It was proven that among the examined species and seasonal types of legumes, the highest total seed and protein yield volume was obtained from both field bean forms, traditional and determinate one. The lowest yield was achieved from blue lupine. The yield of winter wheat grain oscillated around 5.6 t ha-1. Blue lupine seeds were characterised by the highest total protein content. Seeds of both field bean forms were distinguished by the highest content of potassium, phosphorus, copper and zinc, while blue lupine seeds had the highest content of calcium, magnesium and manganese. The research showed a clear tendency towards a higher winter oilseed rape yield in a field after determinate field bean and seed pea. Spring wheat proved to be the worst previous crop for winter oilseed rape. The tendency for greater accumulation of nitrogen, phosphorus, calcium, copper, iron and zinc in winter oilseed rape seeds was observed in a field after determinate field bean. The lowest content of macronutrients and micronutrients was characteristic for seeds of winter oilseed rape grown after spring wheat. Winter oilseed rape seeds in a field after determinate field bean and blue lupine were rich in prof. dr hab. Gabriel Fordonski, Chair of Entomology, Phytopathology and Molecular Diagnostics, University of Warmia and Mazury in Olsztyn, Pl. Łodzki 5,10-727 Olsztyn, Poland, e-mail: gabriel.fordonski@uwm.edu.pl * This study was supported with funds of the Polish Ministry of Agriculture and Rural Development under the project No.HOR. 3.3.3.

Effects of weather conditions during different growth phases on yield formation of winter oilseed rape

Winter oilseed rape (WOSR) is an important oil and protein crop in Europe, used in biofuel production and as protein source in livestock farming. In contrast to cereals, WOSR seed yields are still increasing in most countries but yield stability was not improved during the last decades.In our study, we analyzed the effects of weather conditions during different growth stages on maximum seed yield, maximum oil yield, number of seeds per m2 and 1000-seed weight to get further information on yield formation processes.Field trials performed at 34 environments (site×year combinations) representing different soil characteristics and climate regions in Germany were used for the analysis. About 40% of seed yield variability could be explained by weather conditions during specific growth phases. The most important phenological phases thereby were: onset of pods and seeds (BBCH 50–65) and seed development (BBCH 71–79). During onset of pods and seeds, yield was significantly influenced by temperature, radiation and drought stress. Assimilate availability during this phase determines the number of seeds per m2 (sink size). After flowering, only temperature significantly affected WOSR yield. Temperature is the major parameter determining the duration of growth stages. Lower temperature elongates the time of assimilate production and translocation to the seeds. During this growth stage, seed weight is determined. In our data sets, low sink size was not yield limiting due to compensatory effects between the yield components number of seeds per m2 and 1000-seed weight. Yield response pattern suggests that WOSR yield is predominantly source-limited, especially during the late reproductive phase.