Relationships between seed yield and growth characters,yield components,seed quality of summer-type oilseed rape (Brassica napus L.)

Summary Five genotypes of rapeseed were observed in the field on a single plant and plot basis to evaluate growth characteristics, yield, yield components and seed quality. Observations were made in two years at two locations on three seeding date and three seeding rate treatments. Correlation of seed yield with growth characters demonstrated no consistent trend, indicating that an early maturity and high seed yield should be possible. Harvest index was strongly correlated with seed yield. Percent seed oil and protein were not directly related to seed yield.     

氮钾配施对油菜产量及氮素利用的影响

实际生产中氮钾肥投入不平衡严重限制了氮肥肥效及作物的产量潜力。为了探明不同施氮量下钾肥施用对油菜产量及氮素利用的影响,于2016—2017年及2017—2018年在湖北省武穴市开展连续2年的田间试验,采用氮钾两因素完全试验设计,设氮0、90、180、270 kg N hm-2和钾0、60、120、180 kg K2O hm-2各4个水平。在油菜成熟期取样测定产量、地上部氮钾积累量以及氮肥利用率。结果表明,在钾供应不足时(K0和K60),冬油菜施用氮肥的平均增产率为113.7%,而在钾供应充足的条件下(K120和K180),施用氮肥的平均增产率高达172.9%;与K0处理相比, K120处理冬油菜氮肥回收利用率平均提高了16.6%,继续增施钾肥对不同施氮量下冬油菜氮肥回收利用率的进一步提高无显著影响;达到区域平均产量时,钾供应充足较低钾(K60)投入平均降低33.9%的氮肥用量。综上所述,氮钾配施显著提高了冬油菜产量和氮肥利用率,在冬油菜实际生产中除了重视氮肥施用外,应增加钾肥投入,通过优化氮钾肥配施比例可进一步提高油菜产量,实现冬油菜高产和养分高效。     

Heat stress during seed development affects forage brassica (Brassica napus L.) seed quality

In two consecutive seasons, forage rape (Brassica napus L.) plants were exposed to short periods (240°C hr) of heat stress (30°C day/25°C night) during seed filling (80% seed moisture content = S1), at physiological maturity (50% seed moisture content = S2) and at both S1 plus S2 (=S3) in a Biotron before being returned to the field until seed harvest. Seeds were hand harvested at 14% seed moisture content and their quality assessed by measuring germination, seed vigour (using the accelerated ageing and conductivity tests) and seed mass (as determined by thousand seed weight). Heat stress at both S1 and S2 caused a small (<10%) but significant reduction in germination in both seasons. There was a significant heat stress timing interaction in the first but not the second season. Reductions in germination were a result of increased abnormal seedling production not seed death. All three heat stress treatments significantly reduced seed vigour, with S3>S2>S1. Seed mass was reduced by heat stress at S1 but not at S2. Variable seed vigour in high‐germinating New Zealand‐produced forage rapeseed lots is most likely explained by short periods of heat stress during seed development.     

Impact of low linolenic acid content on seed yield of winter oilseed rape (Brassica napus L.)

An essential quality improvement of rapeseed oil can be obtained by reduction of its linolenic acid (C18:3) content from about 10% to less than 3% of the total fatty acids. Genotypes low in C18:3 have been developed by mutagenesis. The initial summer rapeseed mutant had been low yielding and highly susceptible to various diseases. It has been debated whether the low C18:3 character can be successfully combined with high seed yield for physiological reasons. Therefore, the low linolenic character of mutant M48 was transferred into high-yielding genotypes by repeated backcrossing to well-adapted low erucic acid, low glucosinolate (00-) winter rapeseed cultivars. Lines with low C18:3 content were selected from BC3 and BC4 generations and examined in 1990–95. Positive selection response for seed yield was shown to continue over the years. Presently, the best lines are yielding as well as the control cultivars being equivalent also in oil and glucosinolate contents. In order to test the effect of a low C18:3 content on seed yield, plants with low and with high C18:3 content, respectively, were selected from 16 segregating BC5-F₂ populations and bulked to form 32 F₃ populations. These ‘isogenic’ bulk populations were tested for field performance at four locations in 1995. The results show that C18:3 content of the seed oil is not associated with seed yield, oil content, beginning of flowering, plant height and disease resistance. Means of relative seed yield for the high and the low linolenic F₃ bulk populations were not significantly different with 88.0% and 86.9% of the control cultivars, respectively. There was a significant interaction between genotypes with high or low C18:3 content and location. This shows that under specific environmental conditions a low C18:3 content may be either favourable or unfavourable. The results indicate that the low C18:3 character of the original mutants per se does not cause a decrease in seed yield, oil content or general field performance.     

A comparison of traditional and haploid-derived breeding populations of oilseed rape (Brassica napus L.) for fatty acid composition of the seed oil

Summary Microspore embryogenesis technology allows plant breeders to efficiently generate homozygous micros-pore-derived breeding populations of oilseed rape (Brassica napus L.) without traditional generations of inbreeding. This study was conducted to compare the frequency distribution of microspore-derived population and single seed descent populations with respect to fatty acids of seed oil. Both microspore-derived populations and single seed descent populations were produced from each of three crosses made between selected parents containing contrasting amount of erucic, oleic, linoleic and linolenic acids. The fatty acid content of F₃ plants derived lines (F₅ seed) developed by single seed descent was compared to that of microspore-derived populations. The means, ranges and distribution pattern of seed fatty acid contents were similar in both populations for each fatty acid studied, although a few heterozygous lines were observed in the single seed descent populations. The results indicated that microspore-derived population form random, homozygous F₁ plant derived gametic arrays for all fatty acids evaluated. Selection for altered fatty acid composition in microspore-derived and single seed descent homozygous populations should be equally efficient, in the absence of linkage of traits investigated.     

Hybridization of radish (Raphanus sativus L.) and oilseed rape (Brassica napus L.) through a flower-culture method

Summary Hybridization between radish and oilseed rape has been cumbersome, requiring elaborate embryo rescue techniques. With a modified flower culture method, we have achieved successful hybridization between radish and (transgenic) oilseed rape without the laborious and technically demandingin vitro ovule or embryo rescue techniques.The hybrid nature of the intergeneric hybrids was demonstrated using morphological traits, and DNA analyses. The described method will facilitate the generation ofRaphanobrassica hybrids useful for biosafety studies of the potential for transgenes to spread in weedyCruciferae as well as for breeding programs aimed at introducing useful radish genes, e.g. nematode resistance genes, into oilseed rape.     

Inheritance of progoitrin and total aliphatic glucosinolates in oilseed rape (Brassica napus L)

Inheritance of progoitrin and total aliphatic glucosinolate concentrations were investigated in oilseed rape, using parental, F₁, F₂ and first backcross generations, derived from a cross between resynthesized spring rape and a double-low spring rape cultivar. Progoitrin and total aliphatic glucosinolate concentrations were measured in mature seeds of single plants from these generations, using micellar electrokinetic capillary chromatography. For progoitrin, an additive/dominance model of gene action adequately explained the variation among the generation means, but for total aliphatic glucosinolate concentration, non-allelic interactions were also detected. Predictions based on estimates of the genetic parameters indicated that recombinant inbred lines, rather than second cycle hybrids, appeared to offer a better prospect of reducing glucosinolate concentrations in this material. Estimates of the minimum number of genes controlling these two characters were broadly in line with the number required for the known stages of their biosynthesis. This revised version was published online in July 2006 with corrections to the Cover Date.     

Effect of depth of fertilizer banded-placement on growth,nutrient uptake and yield of oilseed rape (Brassica napus L.)

A better understanding of crop growth and nutrient uptake responses to the depth of fertilizer banded-placement in the soil is needed if growth and nutrient uptake responses are to be maximized. A two-year field study covering two rape seasons (2010–2011 and 2011–2012) was conducted to examine the effect of banded-placement of N–P–K fertilizer at various depths on growth, nutrient uptake and yield of oilseed rape (Brassica napus L.). The results showed that fertilization at 10 cm and 15 cm soil depth produced greater taproot length and dry weight than fertilization at 0 cm and 5 cm. 0 cm and 5 cm deep fertilization significantly increased the lateral root distribution at 0–5 cm soil depth, while 10 cm and 15 cm deep fertilization induced more lateral root proliferation at 5–15 cm soil depth. At 36 days after sowing (DAS), 5 cm deep fertilization produced better aboveground growth and nutrient uptake than 10 cm and 15 cm deep fertilization. However, reversed results were observed after 36 DAS. 10 cm and 15 cm deep fertilization produced more rapeseed than 0 cm and 5 cm deep fertilization, moreover, the yield difference was more significant in drought season (2010–2011) than in relatively normal season (2011–2012). In summary, these results preliminarily suggest that both 10 cm and 15 cm are relatively proper fertilizer placement depth when the practice of banding fertilizer is used in oilseed rape production. But from the viewpoint of diminishing the production cost, 10 cm deep fertilization should be recommended in actual farming. Because 15 cm deep fertilization may require higher mechanical power input, and thus resulting in higher cost of production.     

Influence of leaf and silique photosynthesis on seeds yield and seeds oil quality of oilseed rape (Brassica napus L.)

With the purpose of enhancing oil production, the present work was carried out to elucidate relationships between photosynthesis of leaves, siliques and seeds yield and seeds oil accumulation of oilseed rape. Field trials, in which two repeated experiments was carried out during 2012–2014 growth season, a rape hybrids the “Qin You No.7” (Brassica napus L.) variety was taken into account. The results showed that, on rape plant the photosynthetic capacity and chlorophyll a, b, carotenoid contents of leaf were significantly higher than that of silique shell. Oil content of 94.7% was achieved in young seeds (sampled at 25th day after flowering ending stage of the tested rape plant) versus to mature seeds, saturated fatty acids percent was higher whereas oleic acid percent was lower of oil extracted from young seeds. During flowering period of the rape plants tested, area and dry weight of leaves attained maximum, treatments of removing leaves induced reduction in seeds number per silique, siliques number, seeds yield per plant and seeds oil content, these indexes were respectively decreased by 73.6%, 43.4%, 83.4% and 10.5% in maximum, and seeds oil composition was not significantly influenced; during seeds growing period of the tested plants, surface area and dry weight of siliques attained maximum, under shading siliques treatment, the 1000-seed weight, seeds yield per plant and seeds oil content were respectively reduced by 57.5%, 61.4% and 44.7% in maximum, and seeds oil oleic acid (C18:1) and linolenic acid (C18:3) percent was decreased, linolic acid (C18:2) and erucidic acid (C22:1) percent was increased. So for oilseed rape plant during flowering period, surface area and photosynthesis of leaves dramatically influenced siliques number, seeds number and seeds yield; while in seeds growth period, surface area and photosynthesis of siliques greatly influenced 1000-seed yield, seeds yield, seeds oil content and oil composition; oil accumulation in rape seeds initiated early since seeds commencing growth, seed mature degree influenced oil composition of seeds.     

Oxidative damage in forage rape (Brassica napus L.) seeds following heat stress during seed development

A short period (240°C hr; Tb = 25°C) of heat stress (30°C day/25°C night) during forage rape (Brassica napus L.) seed development or at seed physiological maturity can reduce seed vigour, but the extent of oxidative damage associated with this short heat stress was not known. Heat-stressed seeds were assessed for malondialdehyde (MDA) content, hydrogen peroxide (H₂O₂) accumulation, antioxidant enzyme activity, adenylate energy charge and seed ultrastructural integrity, and compared with that of non-heat-stressed seeds. Heat stress increased both MDA content and H₂O₂ accumulation by 35%–50%, reduced antioxidant enzyme activity by between 12% and 67%, and significantly reduced adenosine energy charge. Transmission electron microscope images showed clear evidence of seed deterioration in heat-stressed seeds, including ruptures in cell wall and plasma membranes, fused lipid bodies and damaged mitochondria. Heat stress at physiological maturity caused more oxidative damage than the same heat stress during seed development. Seed vigour decreased as H₂O₂ accumulation increased and antioxidant enzyme activity decreased, but no direct relationship between lipid peroxidation and seed vigour was established. The extent of damage resulting from even shorter periods of heat stress (<240°C hr) before or at seed physiological maturity requires investigation.     

Emergence and performance of volunteer oilseed rape (Brassica napus) in different crops

Volunteer oilseed rape (OSR, Brassica napus L.) causes various agronomic problems in crop rotations and can contribute to gene dispersal by pollen and by seed admixture. A 4-year field experiment (2008–2011) was set up in south-west Germany to investigate the performance of volunteers derived from two OSR cultivars with different levels of seed dormancy. Volunteers of a high-dormancy (HD) and a low-dormancy (LD) OSR cultivar were deliberately generated by spreading 10,000 seeds m⁻² on a field in August 2008 and 2009. Four different crops were grown on that area in the first year following the seed rain: winter wheat (Triticum aestivum L.), winter turnip rape (Brassica rapa L.), spring barley (Hordeum vulgare L.) and field pea (Pisum sativum L.). In the second year, maize (Zea mays L.) was sown uniformly across all plots. Numbers of OSR seedlings emerging in early autumn shortly after seed rain were not connected with the size of the soil seed bank in early spring of the following year. The seeds of the HD-cultivar formed a much greater soil seed bank (up to 14% of the initially spread seed number) compared with the LD-cultivar (up to 1.3%) in the soil layer of 0 to 30 cm in early spring 2009 and 2010). Across all crops, considerably more volunteers of the HD-cultivar than of the LD-cultivar were present at several survey dates in the first year following seed rain. The highest number of volunteers originated from the HD-cultivar with up to 11 volunteers m⁻² in winter turnip rape compared with a maximum of 0.48 plants m⁻² in the other crops. Cultivar-specific differences in volunteer density were observed as well in maize two years after OSR seed rain. Flowering and seed setting volunteers were only present in 2010 and the flowering time was crucially overlapping with that of sown winter OSR. The reproductive ability (seeds produced m⁻²) of the LD-volunteers was five times lower in winter turnip rape than of the HD-volunteer; a similar trend was observed for the OSR volunteers in the other host crops.Strategies to definitely reduce unwanted effects of OSR volunteers, such as gene flow, should include the use of LD-cultivars with a low potential to form a soil seed bank, particularly if selective herbicides are not available, for instance in broad-leaved crops, or if the volunteers are herbicide-tolerant.     

油菜不同产量类型品种氮素吸收与利用特性研究

摘要: 【研究目的】探讨甘蓝型油菜不同产量类型品种氮素吸收与利用特性。【方法】在不同土壤肥力条件下以甘蓝型油菜品种（2006-2007年度73个、2007-2008年度98个）为材料,成熟期测定各器官干物重、氮素含量,采用组内最小平方和动态聚类方法对供试品种产量进行聚类。研究不同产量类型品种氮素积累与分配差异。【结果】结果表明：供试品种间产量差异很大,类型间差异显著。随着产量增加,氮素吸收总量、氮素籽粒生产效率增加,籽粒氮素积累量增加,茎枝、果壳氮素分配比例下降,籽粒氮素比例增加。土壤肥力高,植株吸氮总量增加,氮素籽粒生产效率降低。【结论】增加氮素吸收总量,促进氮素向籽粒中输送,使得高产和高氮素利用效率统一。     

Direct plant development from microspore-derived embryos of winter oilseed rape Brassica napus L. ssp. oleifera (DC.) Metzger

The influence of temperature/photoperiod treatment and gibberellic acid concentration (0, 0.1 or 1.0 mg/l) on direct conversion of microspore-derived embryos (MDEs) to plantlets of winter oilseed rape was investigated. Physiologically mature, 21-day-old MDEs were transferred to a solid B5 medium supplemented with gibberellic acid, and cultured at 24 ^°C, 4 ^°C or 1 ^°C for 14 days, and then at 24 ^°C for the next 21 days. Low temperature was linked with short photoperiod (8 h light/16 h dark), and high temperature was linked with long photoperiod (16 h light/8 h dark). The highest embryo conversion rate was at 1 ^°C with over 70%, compared to<20% at 4 ^°C. Two-way analysis of variance confirmed the significance of the effect of temperature/photoperiod treatment. By contrast, gibberellic acid concentration had no significant effect on stimulation of shoot development from apical meristems of MDEs. Roots developed from apical root meristems of MDEs very easily. The best obtained conversion rate of MDEs induced with cold treatment at1 ^°C for 14 days was 86.5%. Observations on morphological development of MDEs showed clear differences in reaction at various temperature/photoperiod treatments. This revised version was published online in August 2006 with corrections to the Cover Date.     

Effects of Waterlogging Followed by a Salinity Peak on Rapeseed (Brassica napus L.)

Due mainly to alterations in plant metabolism, lack of oxygen and excess salts are disturbances that affect crop yields. In different parts of the world crops are subjected t o those disttirbances, simultaneously or successively. Our objective was to determine the effects of a winter waterlogging followed by a spring salt peak on rapeseed yield, A pot experiment, combining waterlogging and salinization was carried out. The waterlogging duration was: 0 (control), 3, 7 and 14 days and the sahnity treatments were peaks of Electrical Conductivity of 5 and 8 dSm⁻¹ and the control. The yield started decreasingfrotn 3 days during waterlogging, mainly due to the lower number of seeds per plant. The salt peak from 5 dSm⁻¹ affected the yield only in plants which had suffered a waterlogging lower than 7 days, showing interaction between salinity and waterlogging, Only salinity reduced oil content. The saline peak affected the K, Ca and Na concentration in plant tissues, but the effect of salinity on rapeseed could be more related to soil water potential than specific ion toxicities or imbalance.     

Genetic control of yield and yield components in winter oilseed rape (Brassica napus L.) grown under nitrogen limitation

Despite its high nitrogen absorption capacity, oilseed rape (OSR) has a low apparent nitrogen use efficiency (NUE), which makes its production highly dependent on nitrogen fertilization. Improving NUE in OSR is therefore a main target in breeding. The objectives of the present work were to determine the genomic regions (QTLs) associated with yield and to assess their stability under contrasted nitrogen nutrition regimes. One mapping population, AM, was tested in a French location for three growing seasons (2011, 2012 and 2013), under two nitrogen conditions (optimal and low). Eight yield-related traits were scored and nitrogen-responsive traits were calculated. A total of 104 QTLs were detected of which 28 controlled flowering time and 76 were related to yield and yield components. Very few genotype × nitrogen interactions were detected and the QTLs were highly stable between the nitrogen conditions. In contrast, only a few QTLs were stable across the years of the trial, suggesting a strong QTL × year interaction. Finally, eleven critical genomic regions that were stable across nitrogen conditions and/or trial years were identified. One particular region located on the A5 linkage group appears to be a promising candidate for marker assisted selection programs. The different strategies for OSR breeding using the QTLs found in the present study are discussed.     

Genetic and functional analysis of tocopherol biosynthesis pathway genes from rapeseed (Brassica napus L.)

Brassica napus L. is one of the most important oilseed crops in the world. Improving oil quality by increasing vitamin E content is a major target of rapeseed breeding. Vitamin E compounds, or tocopherols, are lipid‐soluble antioxidants that are essential nutrients for mammals. In this study, we report the characterization of rapeseed orthologs of the Arabidopsis tocopherol genes VTE1, VTE2 and PDS1. For each gene, at least two homologous sequences were found, and their expression was analysed in different tissues from three rapeseed genotypes. Genetic complementation experiments demonstrated that BnaX.VTE1.b and BnaA.VTE2.b homologs are capable of recovering seed γ‐tocopherol in Arabidopsis mutants. Overexpression of the genes in Arabidopsis Col‐0 shifted the seed tocopherol composition towards higher α‐tocopherol without increasing the total tocopherol content. To address the functionality of BnPDS1 sequences, we performed overexpression tests in Escherichia coli and enzymatic activity analyses. Overall, our results show that the identified sequences from rapeseed are functional orthologs of the Arabidopsis VTE genes and thus have considerable potential as molecular markers for selecting rapeseed with improved seed oil quality.     

甘蓝型油菜每角粒数的全基因组关联分析

每角粒数是油菜重要的产量构成因子,增加每角粒数有助于提高油菜的籽粒产量。利用Illumina 60K SNP芯片对496份具有代表性的油菜资源进行基因型分析,考察该群体在2个环境中的每角粒数,利用MLM和GLM模型进行全基因组关联分析。结果表明,本群体在2个环境中每角粒数的广义遗传力为57.7%。利用MLM和GLM模型分别检测到9个和20个位点,所有MLM位点均得到GLM结果的验证。6个位点与前人定位的QTL重叠,其中2个位点得到2次验证,其余14个是新位点。在7个位点附近找到了候选基因,其中在C09染色体的位点Bn-scaff155761-p74980附近找到已克隆的油菜每角粒数基因BnaC9.SMG7b,在其余6个位点附近找到GRDP1、SPATULA、HVA22D、DA2等已知的拟南芥每角粒数基因的同源基因。本研究结果有助于解析油菜每角粒数的遗传基础及其调控机制,为每角粒数的遗传改良奠定了基础。     

Effects of previous cropping on seed yield and yield components of oil-seed rape (Brassica napus L.)

Information about the effect of the preceding crop or crop combination on the seed yield of oil-seed rape is extremely scarce. Experiments were carried out in northwest Germany to investigate the effect of different preceding crops on the growth, seed yield and yield components of oil-seed rape. The two directly preceding crops, wheat and oil-seed rape, had only a negligible and non-significant effect on the seed yield of the following oil-seed rape crop. Oil-seed rape grown after wheat had more pods per plant, due to an increase in the number of pods on the higher category branches. In contrast, the seed yield and yield components were more affected by the cropping sequence, i.e. the crops 2 years before. Averaged over two experimental years, the greatest yields were observed in oil-seed rape following the sequence peas-wheat (694 g m⁻²), whereas the smallest seed yield occurred after 2 years of oil-seed rape cropping (371 g m⁻²). The differences in the seed yield were again associated with more pods per plant, which compensated for the lower number of plants m⁻², whereas the number of seeds per pod and the mean seed weight were almost unaffected by the previous cropping. It was not possible to relate the described differences to the crop development, since differences in the biomass caused by the previous cropping were only significant at maturity. Oil-seed rape grown after 2 years of oil-seed rape had the highest ratings of stem canker (Leptosphaeria maculans) as well as verticillium wilt (Verticillium dahliae). But the general level of the diseases was low, and therefore other causes for the effects described must be considered.     

Influence of sulfur on apparent N-use efficiency,yield and quality of oilseed rape (Brassica napus L.) grown on a calcareous soil

In the Lorraine region, major soils used for winter oilseed rape are calcareous. Across two pot and two field experiments, we studied the influence of sulfur applied at different levels on apparent N-use efficiency (ANU), yield, glucosinolate (GLS) and oil content of seeds. The soil received a constant dose of 200 kg N ha⁻¹ as ammonium nitrate, urea or cow slurry and three levels of S: 0, 30 and 75 kg ha⁻¹ as ammonium thiosulfate (ATS), MgSO₄ or ATS plus MgSO₄. Apparently, oilseed rape is a N-inefficient crop as revealed by low ANU values which varied within 36 and 53% from field experiment versus 25 and 61% under controlled conditions. In both cases, S additions improved N-use efficiency only at the highest dose of 75 kg S ha⁻¹, which is not attained by ATS with 35 kg S ha⁻¹ (10% v/v). S fertilization increased the GLS contents that were found to be negatively correlated with plant N/S uptake ratios observed at maturity. The most important increase in GLS content by 52% was noted with cow slurry in the pot experiment. But, as a whole, the GLS levels remain below the European norm of 18 μmol g seed⁻¹. Moreover, the oil content (% DM) of seeds decreased (but the total production increased) when the soil was fertilized with N and with or without S. The results showed that N and S nutrition during the growth were tightly linked. Their interactions, as reflected by plant uptake, are synergistic at optimum rates and antagonistic at excessive levels of one of the both. Collectively, the results indicate that S fertilization is required to improve N-use efficiency and thereby maintaining a sufficient oil level and fatty acid quality.