Population dynamics of volunteer oilseed rape (Brassica napus L.) affected by tillage

Volunteer plants of oilseed rape (Brassica napus L.) from persistent seeds in soil can affect subsequent crops. Apart from the agricultural disadvantages, the environment and the marketing of the seeds may also be affected, particularly if plants with special ingredients or genetically modified (gm) plants are grown. In order to investigate the influence of soil cultivation and genotype on seed persistence and gene flow via volunteers, a field experiment was set up testing four tillage treatments and two cultivars in a split-plot design. The cultivars tested were near-isogenic to two gm cultivars. To simulate harvesting losses, 10 000 seeds m⁻² were broadcast on a soil in July. The subsequent tillage treatments were combinations of immediate or delayed stubble tillage by a rotary tiller, primary tillage with plough or cultivator, or zero tillage. Over the following year, the fate of the seeds was determined. Immediate stubble tillage with following cultivator or plough resulted in 586 resp. 246 seeds m⁻² in the soil seed bank. After delayed stubble tillage with following plough, 76 seeds m⁻² were found, and no soil seed bank was built up in the zero tillage treatment. Nevertheless, in the zero tillage treatment, several robust volunteer plants survived the herbicide application before the direct drilling in autumn until following spring. In the zero tillage treatment and in the cultivator treatment, 0.19 volunteers m⁻² resp. 0.06 volunteers m⁻² flowered simultaneously to ordinarily sown oilseed rape in the following crop of winter wheat and produced 73 resp. 18 seeds m⁻². Delayed stubble tillage reduced the risk of gene escape via the soil seed bank, while zero tillage resulted in the highest risk of gene escape by pollen and by production of a new generation of seeds. In terms of a labelling threshold for gm food this number of seeds would be below the threshold of 0.9% of transgenic parts in conventially bred food or feed.     

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.     

Evaluating the effectiveness of isolation distances for field plots of oilseed rape (Brassica napus) using a herbicide-resistance transgene as a selectable marker

The effectiveness of 200- and 400-m isolation distances were evaluated for small-scale trials of oilseed rape (Brassica napus L.). These distances have been used for previous transgenic release experiments and are commonly adopted for production of basic and certified breeders seed. A 400-m² donor plot contained plants with a dominant transgene conferring resistance to the herbicide glufosinate-ammonium. This character was used as a selectable marker to measure the frequency of hybrid formation in 400-m² target plots of non-transgenic rape. Seeds produced by the non-transgenic plants were permitted to fall onto the plots and allowed to germinate. At the first true-leaf stage, the plants were sprayed with glufosinate-ammonium. Surviving plants were resprayed, and a subsample assayed for the presence of the transgene using a colorimetric assay and Southern-blot analysis. The average frequency of hybridization over two replicates was 0.0156% at 200 m and 0.0038% at 400 m. These estimates are within the limits established for the production of basic seed (0.1%). Results indicated that bees were the most likely agent for long-distance pollen dispersal.     

Superior performance of two homozygous diploid lines from naturally occurring polyhaploids in oilseed rape (Brassica napus)

Summary Homozygous diploids in oilseed rape were produced by pipetting drops of 0.1 per cent colchicine into the leaf axils of rooted cuttings from naturally occurring polyhaploids after removing the waxy covering with a scalpel. Trial results from spring and winter rape showed that occasional homozygous diploid lines yielded consistently more oil per ha than the parental varieties. Prospects for breeding oilseed rape as a self-fertilised crop are discussed.     

Waterlogging events during stem elongation or flowering affect yield of oilseed rape (Brassica napus L.) but not seed quality

Oilseed rape suffers from serious waterlogging in many regions of the world limiting the cultivation area for rapeseed. Due to the man‐induced climate change, the risk of severe waterlogging events and associated therewith the damage of rapeseed plants will increase, even in Europe and North America. To investigate the effects of waterlogging on growth, yield and seed quality, rapeseed was cultivated throughout its vegetation period and waterlogged for 14 days at two different growth stages: at stem elongation (BBCH 31) or at floral bud appearance (BBCH 55). The experiments revealed that waterlogging at BBCH 31 affected plant growth and nutrient accumulation and finally resulted in lower yields. Waterlogging at BBCH 55 seriously impaired main racemes, but due to an increased production of secondary racemes, yield losses were lower than after waterlogging at BBCH 31. Oil quality was not affected by any waterlogging treatment under the chosen experimental conditions.     

油菜小孢子培养影响因素及黄籽油菜双单倍体群体的构建

针对我国油菜小孢子培养供体材料一般种植在大田,受外界环境影响较大,出胚率较低的现状,对大田环境条件下小孢子培养的主要影响因素进行了研究。同时,为了构建黄籽油菜双单倍体群体,研究了黄籽油菜的出胚情况。结果表明,不同取样时间对小孢子胚状体再生频率的影响很大;秋水仙素处理游离小孢子对胚状体的诱导有一定的负面影响,浓度越高,影响越大;黄籽油菜的出胚率较低(0.56枚/皿),同样条件下,不到黑籽油菜的1/8。不同黄籽单株间出胚率差异较大,变异幅度在0.04~1.97枚/皿。采用小孢子苗直接移栽大田技术,移栽成活率达89.0%,经染色体加倍后,最终构建了含有127个株系的黄籽油菜双单倍体群体。     

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。     

Seed yield, oil and phytate concentration in the seeds of two oilseed rape cultivars as affected by different phosphorus supply

A greenhouse pot experiment was conducted for studying seed and oil yield, P uptake and phytate concentration in the seed of two oilseed rape cultivars (Brassica napus L. var. Oleifera, cv. Bristol and cv. Lirajet), grown on a soil substrate at different levels of plant available phosphorus (6, 19, 31 and 106 mg P-CAL kg⁻¹ soil, resp.). All other nutrients were maintained at a high level. At maturity, seed yield and seed quality were investigated. An increase in the phosphorus soil supply resulted in a significant (P<0.05) increase in seed and oil yield, oil and P concentration of the seeds, and P transported to the seeds. The phytate-phosphorus concentration ranged from 0.5 to 6.9 g kg⁻¹ in the seeds and from 0.9 to 12.8 g kg⁻¹ in rapeseed meal. Insufficient P supply resulted in a reduced concentration of phosphorus and phytate in the seeds. Significant interactions between the factors cultivar and P supply were found for the traits seed yield, oil yield, and P-harvest index.     

Reducing potential gene escape in time by appropriate post-harvest tillage—Evidence from field experiments with oilseed rape at 10 sites in Europe

Persistence of oilseed rapeseed in soil can result in weed problems but also reduce oil quality of following rape crops or result in unwanted gene escape which is particularly relevant in the context of genetically modified oilseed rape. In this paper data from 13 field experiments at sites in England, Austria and Germany are presented where tillage operations were tested that potentially reduce the build-up of a seed bank. In the majority of experiments seed losses were artificially simulated by broadcasting ca. 10,000 freshly ripened rapeseed m⁻² onto cereal stubbles. Oilseed rapeseedlings in autumn, the seed bank in winter–spring and yields of the following crop winter wheat were assessed as a function of tillage regime. During summer and autumn 19–70% of the seeds germinated and emerged. This part of the population was killed by following tillage operations or herbicide applications. However, 0–29%, in moist years 0–5%, of the initially broadcasted seeds developed dormancy and remained ungerminated in the soil until the following winter–spring.

Delaying incorporation of the seeds by leaving the stubble untouched for up to 4 weeks resulted in a reduced seed bank in almost every case. Also, repeated stubble tillage compared to an early single stubble tillage operation resulted in a smaller seed bank. The type of primary tillage (ploughing versus non-inversion cultivation) had no clear effect. No relation was found between the number of seedlings in autumn and the size of the seed bank the following winter–spring. Grain yield of the following crop winter wheat was not adversely affected by delayed stubble tillage.

The results indicate that stubble tillage aiming at a reduced seed bank of oilseed rape should focus on conditions avoiding induction of secondary dormancy rather than improving germination conditions. This means that, under the climatic conditions of central and western Europe, the stubble should be left untouched for several weeks after harvest before starting the usual tillage sequence with stubble tillage and ploughing or a non-inversion tillage sequence.     

Identification of rape seed cultivars (Brassica napus) by starch gel electrophoresis of enzymes

Summary Isozyme patterns were used to characterize ten commercial rape seed (Brassica napus) cultivars. Extracts of cotyledons were made 4–7 days after germination and separated by electrophoresis on starch gels. A sample of more than 100 plants of each variety was analysed and stained for 4 polymorphic enzyme loci (Lap, Gpi, Acon, and Sdh). Therewith, it was possible to distinguish all ten rape varieties qualitatively by at least one typical enzyme pattern. Further, it could be demonstrated that all pairs of varieties showed clear qualitative differences in isozyme patterns, when only tow loci were screened (Acon, Sdh). Using ² test of homogeneity all pairs of varieties differ significantly in their frequencies of isozyme patterns for Acon and in all but one for Sdh.     

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.     

油菜野芥NSa细胞质雄性不育系的特异性分子鉴定

常规细胞质类型鉴定方法花费时间长、工作量大、鉴定效率低、应用性较差。基于基因组重复序列的PCR技术(rep-PCR)在重复序列丰富的线粒体和原核生物的基因组鉴定中效果较好, 本研究对8份油菜资源的细胞质进行分子鉴定,结果表明rep-PCR可以明确区分甘蓝型油菜中常见的6种雄性不育细胞质。同时对甘蓝型油菜和野芥(Sinapis arvensis)体细胞杂交创建的、育性较为稳定的NSa野芥雄性不育胞质进行了分子特异性鉴定,获得了两条NSa不育胞质的特征DNA条带。但波里马和萝卜质不育细胞质的特异性引物在NSa中不能扩增出特异性片段,说明NSa不属于这两种细胞质类型。本研究结果为该不育胞质系统的利用和知识产权保护提供了理论依据和技术支撑。     

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.     

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.     

Identification of AFLP markers linked to one recessive genic male sterility gene in oilseed rape, Brassica napus

The commercial utilization of heterosis in seed yield by means of hybrid varieties is of great importance for increasing oilseed rape production in China. This requires a functional system for the production of hybrid seed. The Brassica napus oilseed rape line 9012AB is a recessive epistatic genic male sterility (GMS) two‐type line, in which the sterility is controlled by two pairs of recessive duplicate sterile genes (ms1 and ms2) interacting with one pair of a recessive epistatic inhibitor gene (rf). Homozygosity at the rf locus (rfrf) inhibits the expression of the recessive male sterility trait in homozygous ms1ms1ms2ms2 plants. This study was conducted to identify molecular markers for one of the male fertility/sterility loci in the B. napus male sterility line 9012AB. Sterile bulk (BS) and fertile bulk (BF) DNA samples prepared from male sterile and male fertile plants of the homozygous two‐type line 9012AB were subjected to amplified fragment length polymorphic (AFLP) analysis. A total of 256 primer combinations were used and seven markers tightly linked to one recessive genic male sterile gene (ms) were identified. Among them, six fragments co‐segregated with the target gene in the tested population, and the other one had a genetic distance of 4.3 cM. The markers identified in this study will greatly enhance the utilization of recessive GMS for the production of hybrid seed in B. napus oilseed rape in China.     

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.     

甘蓝型油菜小孢子培养影响因素研究及再生苗早期倍性鉴定

对不同年份、不同地点种植的油菜育种材料进行小孢子产胚率鉴定,并以11种不同基因型的甘蓝型油菜品系为供体材料,在武汉田间,分别于初花期和盛花期分离培养小孢子,研究基因型、生态条件、开花时间对小孢子产胚率的影响及秋水仙碱处理的加倍效果,通过采用流式细胞仪测定小孢子再生苗的DNA含量鉴定其倍性,并种植验证.结果表明:相同基因...     

甘蓝型油菜裂角相关性状的遗传与相关分析

抗裂角性是非常重要的油菜性状, 但相关研究报道较少。本研究对11个甘蓝型油菜骨干亲本品系及由其配制的30个不完全双列杂交组合在2个环境下的抗裂角指数及其他7个角果相关性状进行了遗传分析。结果表明, 抗裂角指数遗传变异显著, 遗传上受少数主效基因控制, 效应以加性为主, 显性效应和环境效应影响较小。大部分杂交组合的抗裂角指数杂种优势不显著。抗裂角指数与角果长、果皮重、千粒重和种子直径呈极显著正相关, 与结角密度和角粒数呈极显著负相关。抗裂角性相关性状中, 角果长、千粒重、结角密度和种子直径变异主要由加性方差解释;果皮重和每角粒数主要由显性方差解释。亲本评价分析指出, 作为波里马细胞质雄性不育系统保持系的ZS11B和恢复系的R11其抗裂角性的一般配合力高, 是培育抗裂角杂交油菜品种的首选直接亲本。