Winter Oilseed Rape Cultivars Research Articles

The Influence of Nitrogen and Sulfur Fertilization on Oil Quality and Seed Meal in Different Genotypes of Winter Oilseed Rape (Brassica napus L.)

Adequate nitrogen (N) and sulfur (S) fertilization of oilseed rape crops is necessary to obtain good-quality oil and post-extraction rapeseed meal. The aim of this study was to determine the effect of different doses of N fertilization (100, 160 and 220 kg ha−1) and S (0, 30, 60 and 90 kg ha−1) on the value of seeds of three winter oilseed rape genotypes. Two winter oilseed rape genotypes obtained by mutagenesis (cultivar Polka and breeding genotype PN440) were characterized by changed fatty acid profile. The cultivar Polka, type HO (high oleic), had a high content of oleic acid (C18:1, 78.0%) and the breeding genotype PN440, type HOLL (high-oleic and low-linolenic), had a high content of oleic acid (C18:1, 75.0%) and a low content of linolenic acid (C18:3, 3.0%). We also used the canola type of winter oilseed rape cultivar, Monolit. The analysed winter oilseed rape genotypes responded similarly to the N and S fertilization factors with regard to the content of crude fat and total protein in the seeds and the composition of fatty acids in the oil. N fertilization increased the content of glucosinolates (GLS-alkenyl, indole and total) in seeds, whereas S application decreased the content of saturated fatty acids (stearic acid-C18:0) in oil and increased the content of alkenyl and total glucosinolates (GLSs) in seeds. A significant interaction between N and S was observed for crude-fat and total-protein content. This study suggests that ensuring an adequate supply of both nitrogen and sulfur in the soil is essential for optimizing meal and oil quality in different types of winter oilseed rape cultivars. Proper management of these nutrients can lead to improved oil content and overall crop performance.

Relationships between Flower Opening Time, Environmental Conditions, Corolla Opening Size and Nectar Production in Five Winter Oilseed Rape (Brassica napus L.) Cultivars in China

Abstract Oilseed rape is an economically important crop and provides a good nectar resource. In this study, the nectar secretion characteristics of five winter oilseed rape (Brassica napus L.) cultivars in China were examined throughout the daytime. The correlations of corolla opening size, air temperature and relative humidity with nectar production were also determined. Different daily patterns of nectar secretion were detected in flowers opening at different times of the day, and similar trends were observed among cultivars. The nectar volume and nectar sugar concentration in flowers that opened before 9:00 peaked on the first day. The nectar volume of flowers that opened at 11:00 peaked on the second day, and the nectar sugar concentration peaked on the first day. The total nectar yield of flowers opening before 9:00 (4.422–5.265 μl) was lower than that of flowers opening at 11:00 (7.982–10.646 μl). The average nectar sugar concentration of flowers opening before 9:00 (18.4–23.3%) was higher than that of flowers opening at 11:00 (15.3–17.5%). The nectar volume was positively correlated with air temperature and relative humidity, while the nectar sugar concentration was positively correlated with air temperature and negatively correlated with relative humidity. The nectar volume and nectar sugar concentration were positively correlated with corolla opening size. The glucose/fructose ratio ranged from 0.89 to 1.44. These results will contribute to a better understanding of the nectar secretion patterns of B. napus L. and will support further studies assessing the melliferous potential of B. napus L. and the temporal dynamics of plant-pollinator interactions.

Effect of fungicide treatment and nitrogen fertilisation on the yield of two breeding types of winter oilseed rape cultivars

The effect of three fungicide treatment programmes and the level of spring nitrogen fertilisation on the seed yield of two types ofcultivars of Brassica napus L. sown at two different seeding rates was studied in a field experiment. The subject of the study was anopen-pollinated cultivar ‘Casoar’ and a restored hybrid cultivar ‘Visby’. Three plant protection programmes, two levels of spring nitrogenfertilisation (160 and 220 kg N⋅ha1), and two different seeding rates for each cultivar (‘Visby’—50 and 70 seeds⋅⋅m2; ‘Casoar’—60 and 80 seeds⋅m2) were included. The most intensive protection programme comprised three fungicide treatments: first in autumn at the six-leaves-unfolded stage—BBCH 16, second in spring at the stem elongation stage—BBCH 33, and third at the full flowering stage—BBCH 65. One of two less intensive programmes of plant protection included fungicide application in autumn at the sixleaves-unfolded stage—BBCH 16 and at the full flowering stage—BBCH 65, while the second included fungicide application in spring at the stem elongation stage—BBCH 33 and at the full flowering stage—BBCH 65. The effectiveness of the protection programmes and nitrogen fertilisation was influenced by the intensity of abiotic stress factors. The average yield from the plots protected against pathogens was significantly higher than that from the untreated plots. The increase of nitrogen fertilisation from 160 to 220 kg⋅ha1 also caused a significant increase of average seed yield. The yield of cultivar ‘Visby’ was higher and less dependent on the seeding rate compared to cultivar ‘Casoar’.Keywords: Winter oilseed rape; Cultivars; Disease control; Nitrogen fertilisation; Seeding rate; Sclerotinia sclerotiorum; Leptosphaeria spp.; Alternaria spp. Botrytis cinerea.

Influence of Elevated Temperatures on Resistance Against Phoma Stem Canker in Oilseed Rape.

Cultivar resistance is an important tool in controlling pathogen-related diseases in agricultural crops. As temperatures increase due to global warming, temperature-resilient disease resistance will play an important role in crop protection. However, the mechanisms behind the temperature-sensitivity of the disease resistance response are poorly understood in crop species and little is known about the effect of elevated temperatures on quantitative disease resistance. Here, we investigated the effect of temperature increase on the quantitative resistance of Brassica napus against Leptosphaeria maculans. Field experiments and controlled environment inoculation assays were done to determine the influence of temperature on R gene-mediated and quantitative resistance against L. maculans; of specific interest was the impact of high summer temperatures on the severity of phoma stem canker. Field experiments were run for three consecutive growing seasons at various sites in England and France using twelve winter oilseed rape breeding lines or cultivars with or without R genes and/or quantitative resistance. Stem inoculation assays were done under controlled environment conditions with four cultivars/breeding lines, using avirulent and virulent L. maculans isolates, to determine if an increase in ambient temperature reduces the efficacy of the resistance. High maximum June temperature was found to be related to phoma stem canker severity. No temperature effect on stem canker severity was found for the cultivar ES Astrid (with only quantitative resistance with no known R genes). However, in the controlled environmental conditions, the cultivar ES Astrid had significantly smaller amounts of necrotic tissue at 20°C than at 25°C. This suggests that, under a sustained temperature of 25°C, the efficacy of quantitative resistance is reduced. Findings from this study show that temperature-resilient quantitative resistance is currently available in some oilseed cultivars and that efficacy of quantitative resistance is maintained at increased temperature but not when these elevated temperatures are sustained for a long period.

Oilseed Rape Cultivars Show Diversity of Root Morphologies with the Potential for Better Capture of Nitrogen

The worldwide demand for vegetable oils is rising. Oilseed rape (Brassica napus) diversifies cereal dominated crop rotations but requires important nitrogen input. Yet, the root organ is offering an untapped opportunity to improve the nitrogen capture in soil. This study evaluates three culture systems in controlled environment, to observe root morphology and to identify root attributes for superior biomass production and nitrogen use. The phenotypic diversity in a panel of 55 modern winter oilseed rape cultivars was screened in response to two divergent nitrate supplies. Upon in vitro and hydroponic cultures, a large variability for root morphologies was observed. Root biomass and morphological traits positively correlated with shoot biomass or leaf area. The activities of high-affinity nitrate transport systems correlated negatively with the leaf area, while the combined high- and low-affinity systems positively with the total root length. The X-ray computed tomography permitted to visualize the root system in pipes filled with soil. The in vitro root phenotype at germination stage was indicative of lateral root deployment in soil-grown plants. This study highlights great genetic potential in oilseed rape, which could be manipulated to optimize crop root characteristics and nitrogen capture with substantial implications for agricultural production.

Multi-environmental evaluation of winter oilseed rape genotypic performance using mixed models

The production of winter oilseed rape (WOSR) (Brassica napus) together with increasing seed yields per hectare is one of the strategies for breeding the genetic base of oilseed rape genotypes adapted to different environments. The main objective of this study was to evaluate the genotypic performance of 25 winter oilseed rape genotypes using mixed models. The plant material was examined in five locations in Poland. Field trials were carried out in a randomized complete block design with four replicates. The REML/BLUP was used to estimate genetic parameters. Selection of genotypes was made on the basis of genetic values by the harmonic mean of relative performance these parameters. The mean heritability for genotype had an average value at a high accuracy of selection, while additionally it facilitated selection of agronomically superior individuals. Three restorer lines PN18, PN17 and PN21, CMS ogura line PN64 as well as hybrids PN66 × PN21 and PN64 × PN21 characterized good adaptability and stability of seed yield. There were similarities among the statistics (hat{mu } + hat{g}), adaptability and stability of genetic values in the discrimination of the most productive genotypes by best linear unbiased predictor analysis. Mixed models can be recommended as a potential selection method for the inclusion of new plant material in different oilseed rape breeding programs aimed at developing new WOSR cultivars.

A novel deletion in FLOWERING LOCUS T modulates flowering time in winter oilseed rape

Key messageA novel structural variant was discovered in the FLOWERING LOCUS T orthologue BnaFT.A02 by long-read sequencing. Nested association mapping in an elite winter oilseed rape population revealed that this 288 bp deletion associates with early flowering, putatively by modification of binding-sites for important flowering regulation genes.Perfect timing of flowering is crucial for optimal pollination and high seed yield. Extensive previous studies of flowering behavior in Brassica napus (canola, rapeseed) identified mutations in key flowering regulators which differentiate winter, semi-winter and spring ecotypes. However, because these are generally fixed in locally adapted genotypes, they have only limited relevance for fine adjustment of flowering time in elite cultivar gene pools. In crosses between ecotypes, the ecotype-specific major-effect mutations mask minor-effect loci of interest for breeding. Here, we investigated flowering time in a multiparental mapping population derived from seven elite winter oilseed rape cultivars which are fixed for major-effect mutations separating winter-type rapeseed from other ecotypes. Association mapping revealed eight genomic regions on chromosomes A02, C02 and C03 associating with fine modulation of flowering time. Long-read genomic resequencing of the seven parental lines identified seven structural variants coinciding with candidate genes for flowering time within chromosome regions associated with flowering time. Segregation patterns for these variants in the elite multiparental population and a diversity set of winter types using locus-specific assays revealed significant associations with flowering time for three deletions on chromosome A02. One of these was a previously undescribed 288 bp deletion within the second intron of FLOWERING LOCUS T on chromosome A02, emphasizing the advantage of long-read sequencing for detection of structural variants in this size range. Detailed analysis revealed the impact of this specific deletion on flowering-time modulation under extreme environments and varying day lengths in elite, winter-type oilseed rape.

Productivity, Energy and Economic Balance in the Production of Different Cultivars of Winter Oilseed Rape. A Case Study in North-Eastern Poland

In this study, the agricultural inputs, energy requirements and costs associated with the production of semi-dwarf (PR45 D03 and Avenir) and long-stem (Visby) cultivars of winter oilseed rape were optimized in an experiment with 35-1 fractional factorial design. A field experiment was carried out in the Agricultural Experiment Station in Bałcyny (north-eastern Poland) in 2008–2011. The study investigated the responses of two morphotypes of hybrid cultivars of winter oilseed rape to key yield-forming factors (seeding date, seeding rate, nitrogen fertilization) and yield protection factors (fungal disease control). Agronomic inputs were tested at three levels. Our findings indicate that production technologies (characterized by a different intensity of agricultural inputs) should target the specific requirements of winter oilseed rape cultivars. Semi-dwarf cultivars of winter oilseed rape (PR45 D03 and Avenir) were characterized by higher yield potential at different input levels than the long-stem cultivar (Visby). Semi-dwarf cultivars required higher levels of agricultural inputs than the long-stem cultivar. Semi-dwarf cultivars grown in high-input technologies were characterized by the highest energy efficiency ratio. In contrast, the long-stem cultivar was characterized by the optimal energy input-energy output ratio in the low-input technology. Regardless of cultivar, high-input production technologies were more profitable because the resulting increase in seed yield significantly outweighed the rise in production costs.

Effects of leaf age on chlorophyll fluorescence and antioxidant enzymes activity in winter rapeseed leaves under cold acclimation conditions

Cold acclimation-dependent physiological changes were investigated through photosynthetic activity and some antioxidant enzymes in two winter oilseed rape cultivars (Brassica napus L. ssp. oleifera cvs. Eurol and Hansen) on the basis of leaf age. Chlorophyll fluorescence measurements demonstrated that cold acclimation caused decreased photosynthetic activity in Eurol and Hansen as the leaf age increased. Photosynthetic pigment content declined in both cultivars under low temperature irrespective of leaf age. In Eurol, however, relatively higher total carotenoid content than Hansen may provide a protection against photooxidative damage. Superoxide dismutase, ascorbate peroxidase and glutathione reductase activity in the cold-acclimated leaves of Hansen significantly increased, indicating an effective ascorbate–glutathione cycle activity. In Eurol, however, ascorbate peroxidase and glutathione reductase activity in the cold-acclimated younger leaves lowered and hydrogen peroxide detoxifying system collapsed. As a result, decreased photosynthetic activity in the young leaves of Hansen under low temperature could be manifested as a metabolic response that downregulate photosynthesis to attain cold-acclimated state. In the case of Eurol, cold acclimation process caused oxidative stress. In summary, the changes in the chlorophyll fluorescence parameters in the young leaves of Hansen are derived from some metabolic regulation as a result of cold acclimation, whereas in Eurol, it is due to oxidative stress triggered by low temperature. Leaf maturation mitigated the adverse effects of low temperature in the leaves of Eurol and Hansen.

Is leaf age a predictor for cold tolerance in winter oilseed rape plants?

In the present study, low temperature-dependent physiological changes were investigated through photosynthetic activity and some endogenous mechanisms in two winter oilseed rape cultivars (Brassica napus L. ssp. oleifera cvv. Eurol and Hansen) on the basis of leaf age. Chlorophyll fluorescence measurements demonstrated that low temperature caused decreased photosynthetic activity in both cultivars. However, photosynthetic apparatus in the young leaves of Hansen is more tolerant to low temperature as demonstrated by lower F0 (minimum fluorescence yield) and 1-qp (excitation pressure of photosystem II), higher Fm (maximum fluorescence yield), Fv/Fm and non-photochemical quenching (NPQ) compared with Eurol. In addition, young leaves of Hansen represented marked increase in some antioxidant enzyme activities (superoxide dismutase (SOD), ascorbate peroxidase (APX) and glutathione reductase (GR)) during cold exposure. In the young leaves of Eurol, however, APX and GR activity was decreased by low temperature, indicating lower efficiency of ascorbate-glutathione cycle. Lower antioxidant activity in the young leaves of Eurol may be responsible for increased malondialdehyde (MDA), H2O2 and membrane damage and decreased chlorophyll content as a result of oxidative damage during cold exposure. In the cold-stressed mature leaves, both cultivars represented similar antioxidant capacities and photosynthetic efficiency. As a consequence, coordinated increase in SOD, APX and GR activities, increased capacity to keep quinone A (QA) in an oxidised state (as indicated by lower 1-qp) and accumulation of soluble sugar and proline could be mainly attributed to higher level of tolerance of the young leaves of Hansen to low temperature when compared with Eurol.

Genotype by environment interaction for alkenyl glucosinolates content in winter oilseed rape (Brassica napus L.) using additive main effects and multiplicative interaction model

Genotype by environment interaction is important for quantitative traits in all organisms. All organisms are exposed on the influence of different environmental conditions. Changes in the performance of genotypes across different environments are referred to as genotype by environment interactions. The objective of this study was to assess genotype by environment interaction for alkenyl glucosinolates content in winter oilseed rape cultivars grown in West Poland by the additive main effects and multiplicative interaction model. The study comprised of 25 winter oilseed rape genotypes (15 F1 CMS ogura hybrids, eight parental lines and two European cultivars: open pollinated Californium and F1 hybrid Hercules), evaluated at five locations in a randomized complete block design, with four replicates. Across location average alkenyl glucosinolates content of the tested genotypes ranged from 4.13 (for PN66 × PN21) to 8.53 μmol g−1 of seeds (for Californium). The across genotype averages alkenyl glucosinolates content at locations varied substantively from 2.43 μmol g−1 of seeds in Łagiewniki, to 8.85 μmol g−1 of seeds in Borowo. In the AMMI analyses, 53.92 % of the alkenyl glucosinolates content total variation was explained by environments, 13.06 % by genotypes, and 16.02 % by genotype × environment interaction. The hybrid PN66 × PN21 is recommended for further use in the breeding program due to its low average alkenyl glucosinolates content (4.13 μmol g-1 of seeds) and the best stability across environments (ASV = 0.255).

Wpływ opóźnionego terminu siewu rzepaku ozimego na wielkość i jakość plonu nasion

The sowing date of winter oilseed rape affect plant development and yield to a large extent, but yield components have not been well documented yet in the conditions of Poland. Therefore, research was undertaken to determine the impact of the delayed date of winter oilseed rape on the development of plants and the quantity and quality of the seed yield. A field study was conducted in the seasons 2013/2014 - 2015/2016 at the Experimental Institute of Cultivar Assessment in Skoloszow, Poland. Experimental factors were: the seed sowing date (optimal, delayed) and winter oilseed rape cultivars (Monolit, Arsenal F1). This study has indicated that sowing the seeds in a delayed time affected shortening of the plant growing period, but it did not differentiate the seed yield. It has been found that the optimal sowing date increased the plant density prior to harvest, whereas a delayed sowing date resulted in an increase in the number of seeds per silique. The cultivar Arsenal F1 increased seed yield by 0.87 t∙ha-1 as compared with the cultivar Monolit. Delayed sowing date increased the content of fibre and zinc in seeds, and decreased the content of protein, phosphorus and potassium as compared with the optimal time.

The effect of biostimulators on the content of crude oil and total protein in winter oilseed rape (Brassica napus L.) seeds

ABSTRACTThe objective of the study was to determine the effect of the experimental factors on the seed quality of three winter oilseed rape cultivars. The following factors were studied: I-three winter oilseed rape morphotypes: population, hybrid restored characterised by a semi-dwarf growth pattern, hybrid restored characterised by a conventional growth pattern; II-two sowing methods: a spacing of 22.5 cm, a spacing of 45.0 cm; III-four types of biostimulants: control-no biostimulants, the biostimulant Tytanit®, Asahi®SL, Silvit®. Seed samples were subjected to chemical analysis to determine: crude oil, total protein and crude fibre. Natural stimulants of plant growth and development contributed to an increase in crude oil ranging from 7.4 to 9.5 g kg–1 d.m., on average, compared with control. The biostimulants applied did not affect total protein content which was, however, affected by meteorological conditions in individual study years as well as the genetic factor. Biostimulants increased crude fibre content compared with control.

Genetic variation for shoot elongation before winter and its correlation with vernalization requirement in winter oilseed rape (Brassica napus L.)

Changing climatic conditions in north-western Europe are accompanied by occasional extreme weather conditions. This requires breeding of winter oilseed rape cultivars which are resilient to diverse abiotic stress factors, e.g. frost, drought and heat. The degree of vernalization requirement of winter oilseed rape has been found to be related to frost tolerance and winter hardiness. Shoot elongation before winter in particular has been identified as one decisive factor for frost tolerance in winter oilseed rape. However, the relationship between vernalization requirement and shoot elongation before winter is not known. In the present study the genetic variation for shoot elongation before winter and vernalization requirement of 19 genetic diverse breeding lines and cultivars were analyzed. Autumn and spring sown field experiments in multiple environments were performed to determine shoot elongation before winter and vernalization requirement, respectively. In spring sown field experiments, genotypes with a low vernalization requirement were characterized by the occurrence of long bolting plants with flower buds. Large and significant genotypic variation was found for shoot length in the autumn sown and spring sown environment. Broad sense heritability was quite high for shoot length in the spring sown environment (h2 = 97%), whereas it was only of medium size for shoot length before winter (h2 = 62%). Although the correlation between shoot length before winter and shoot length in the spring sown environment was positive (Spearman’s rank rS = 0.48*), a number of genotypes with reduced shoot elongation before winter and low vernalization requirement were identified. Results indicate that genotypes with a reduced shoot elongation before winter independent of their vernalization requirement can be selected in breeding programs.

Effects of host plant resistance and fungicide application on phoma stem canker, growth parameters and yield of winter oilseed rape

Multifactorial field trials were conducted over three cropping seasons (2012–2015) to assess the effects of selection of triazole fungicides when applied either alone or in combination on growth of winter oilseed rape, development of phoma stem canker, crop wintering and crop yield. The plots consisted of four winter oilseed rape cultivars differing in their levels of resistance to phoma stem canker and subplots of five fungicides with growth regulatory activity (prochloraz/tebuconazole, mepiquat/metconazole, tebuconazole, tebuconazole/prothioconazole and a mixture of fluxapyroxad/tebuconazole) which were applied twice; in autumn (BBCH 14–18) and in spring (BBCH 30–39). Visual scoring such as growth parameters like plants per m2 and plant height, yield parameters like number of side branches, pods and seeds per plant, thousand grain weights and seed yield as well as evaluation of phoma leaf spots and basal stem canker were performed using standard procedures. Plant height was significantly affected by cultivars and fungicide treatments. In contrast, winter killing (%) was not reduced significantly. Application of mepiquat/metconazole reduced the winter killing below 10% compared to the untreated control. Development of phoma stem canker was affected by fungicides and cultivars. At the final rating date (BBCH 81), the moderately resistant cultivars Genie and Vitara exhibited less disease severity than the susceptible cultivars Elektra and PR 46W20 in untreated plots. Fungicide treatments were more effective in reducing the disease in moderately resistant cultivars than in susceptible ones. The lowest percentage of disease severity was achieved when fluxapyroxad/tebuconazole combination was applied to plants. To our knowledge, this study is the first to report multi-year efficacy of fluxapyroxad/tebuconazole against phoma stem canker in oilseed rape cultivations. Cultivars showed differences in all yield parameters. However, with the exception of seed yield the application of fungicides did not significantly impact the different yield parameters. Application of fluxapyroxad/tebuconazole was the most effective treatment in reducing yield losses.

Genetic variation for vernalization requirement of winter oilseed rape

Global warming is currently enabling the expansion of winter oilseed rape cultivation to previously unsuitable regions. Nevertheless, extreme frost events may lead in some years to severe winter damage. On the other hand, early flowering winter oilseed rape cultivars are wanted because of increasingly warm temperatures in spring. An assumed correlation between winter hardiness and vernalization requirement therefore needs to be investigated. Analysing the genetic variation for vernalization requirement in a large set of genetically diverse winter oilseed rape genotypes revealed large and significant variation for this trait.

Effectiveness of Rlm7 resistance against Leptosphaeria maculans (phoma stem canker) in UK winter oilseed rape cultivars.

The Rlm7 gene in Brassica napus is an important source of resistance for control of phoma stem canker on oilseed rape caused by the fungus Leptosphaeria maculans. This study shows the first report of L. maculans isolates virulent against Rlm7 in the UK. Leptosphaeria maculans isolates virulent against Rlm7 represented 3% of the pathogen population when cultivars with the Rlm7 gene represented 5% of the UK oilseed rape area in 2012/13. However, the Rlm7 gene has been widely used since then, representing >15% of the UK oilseed rape area in 2015/16. Winter oilseed rape field experiments included cultivars with the Rlm7 gene, with the Rlm4 gene or without Rlm genes and took place at five sites in the UK over four cropping seasons. An increase in phoma leaf spotting severity on Rlm7 cultivars in successive seasons was observed. Major resistance genes played a role in preventing severe phoma leaf spotting at the beginning of the cropping season and, in addition, quantitative resistance (QR) in the cultivars examined made an important contribution to control of phoma stem canker development at the end of the cropping season. Deployment of the Rlm7 resistance gene against L. maculans in cultivars with QR in combination with sustainable disease management practices will prolong the use of this gene for effective control of phoma stem canker epidemics.

The effect of biostimulants on the glucosinolate content in winter oilseed rape (Brassica napus L.) seeds

The objective of the study was to determine the effect of biostimulants on the concentration of harmful sulphuric compounds called glucosinolates in the seed of three winter oilseed rape cultivars. An experiment was arranged as a split-split-plot design with three replications. The following factors were examined: I – three winter oilseed rape morphotypes: a population morphotype (cv. Monolit), a semi-dwarf restored cultivar (PR 44D06) and a standard restored cultivar (PT 205); II – two sowing methods: between-row spacing of 22.5 cm and 45.0 cm; III – four types of biostimulants: control, Tytanit<sup>®</sup>, Asahi<sup>®</sup>SL and Silvit<sup>®</sup>. The lowest concentration of glucosinolates was determined in the population cv. Monolit (on average 8.84 µmol/g) and the highest in the restored semi-dwarf cv. PR 44D06 (on average 9.84 µmol/g). Application of all of the biostimulants contributed to a significant decline in the concentration of harmful sulphuric compounds compared with control, the lowest concentration being recorded following the spraying with Silvit<sup>®</sup> (on average 8.88 µmol/g). Statistical calculations did not confirm a significant effect of two sowing methods on the characteristics examined.

New winter oilseed rape varieties – seed quality and morphological traits depending on sowing date and rate

Many studies have focused on research about impact of time and density of sowing on the agronomic characteristics of different crops. However, the number of studies investigating such a response on the qualitative composition of different types of winter oilseed rape varieties is still limited. The aim of the research was to determine the effect of sowing date and density on yield, protein and oil content and quality of winter oilseed rape varieties: open-pollinated, a typical hybrid of traditional type of growth and a new semi-dwarf hybrid, which biology and yielding have not been thoroughly established. This experiment was conducted applying four sowing dates (August 14, August 25, September 4, September 15), three winter oilseed rape cultivars (PR45D03 -semi-dwarf hybrid, PR46W31 – hybrid, Californium – open-pollinated) and four sowing rates (30, 40, 50, 60 seeds/m2). Among the compared sowing dates, August 25 proved to be optimal for yielding of the tested winter oilseed rape cultivars. Semi-dwarf variety contained less protein and glucosinolate in seeds, but more oil in comparison to other studied varieties (hybrid and open-pollinated). The yields did not differ significantly within a density of 40, 50, 60 seeds/m2, so it is important result, especially for the agricultural practice.

Effect of protection against pathogens on yield of two breeding types of winter oilseed rape cultivars under high level of nitrogen fertilization

Effect of protection against pathogens on yield of two breeding types of winter oilseed rape cultivars under high level of nitrogen fertilization