Optimizing harvest timing in rapeseed (Brassica napus L.): Balancing oil yield, metabolic quality, and field efficiency

Effect of increasing spring doses of nitrogen on yield and oil content in seeds of oilseed rape (Brassica napus L.)

Influence of two-stage harvesting on the properties of cold-pressed rapeseed (Brassica napus L.) oils

Evaluating the application of controlled release urea for oilseed rape on Brassica napus in a regional scale: The optimal usage, yield and nitrogen use efficiency responses

Leptosphaeria maculans, the causal agent of phoma stem canker on oilseed rape, is an important pathogen in oilseed rape growing regions of the world, including Australia. Survival ofL. maculansand associated mycobiota on oilseed rape stubble buried for 13 months in field soil and in sandy soil was studied under South Australian environmental conditions. Stubble weight decreased significantly by the end of the burial period, more so in field (53·7%) than in sandy soil (22%). Pseudothecia did not develop on stubble buried in field soil and few formed when buried in sandy soil. Moist incubation of stubble following retrieval from both media generated pseudothecia; however, pseudothecial development ceased on stubble that had been buried for 10 and 12 months in field and sandy soil, respectively. In total, 20 and 36 genera of fungi were isolated from stubble before and after burial, respectively.Alternariaspp.,L. maculansandStemphylium botryosumwere isolated from 81·7, 70 and 60% of stubble pieces before burial, respectively. Isolation frequency of these species decreased significantly throughout the burial period in both media. Conversely, isolation frequency ofStachybotrys chartarum,Fusariumspp. andTrichodermaspp., having pre‐burial frequencies of 26·7, 16·7 and 2·5%, respectively, increased over the burial period regardless of soil type. These findings suggest that inoculum production ofL. maculansdecreases with the increasing burial duration in field soil over 10 months, before ceasing, and this may be due to associated mycobiota.

مطالعه با هدف شناسایی برخی شاخص‌های فیزیولوژیک و زراعی مناسب برای گزینش ژنوتیپ‌های متحمل به خشکی کلزای بهاره اجرا گردید. آزمایش به‌صورت کرت‌های خرد شده بر پایه بلوک‌های کامل تصادفی با سه تکرار در ایستگاه خسروشاه مرکز تحقیقات و آموزش کشاورزی و منابع طبیعی آذربایجان شرقی طی دو سال زراعی 1394 و 1395 اجرا گردید. فاکتور اصلی تنش کمبود آب با سطوح: بدون تنش، تنش از زمان گل‌دهی و از خورجین‌دهی تا رسیدگی و فاکتور فرعی ژنوتیپ شامل: RGS003، ظفر، ساری گل، زرفام و دلگان بودند. نتایج نشان دادند بروز خشکی از مراحل گل‌دهی و خورجین‌دهی باعث افزایش معنی‌دار دمای برگ و کاهش معنی‌دار مقدار نسبی آب برگ (RWC)، هدایت روزنه، شاخص کلروفیل برگ، تعداد خورجین در بوته، تعداد دانه در خورجین، وزن هزار دانه، درصد روغن، عملکرد دانه و روغن گردید ولی بیشترین تأثیرپذیری به هنگام وقوع تنش از مرحله گل‌دهی بود. بنابراین تأمین آب در این مرحله اولویت بیشتری خواهد داشت. کمبود آب با اثر کاهشی روی همه اجزای عملکرد باعث افت عملکرد دانه گردید. همبستگی‌های معنی‌داری بین دمای برگ، RWC ، شاخص کلروفیل برگ و هدایت روزنه با همدیگر و با عملکرد دانه و روغن و اجزای عملکرد دانه دیده شد. شاخص‌های مذکور از کارایی قابل قبولی در شناسایی اثرات کمبود آب روی ژنوتیپ‌های بهاره کلزا برخوردار بودند. ژنوتیپ RGS003 با کسب بیشترین مقدار نسبی آب برگ، هدایت روزنه و شاخص کلروفیل برگ، همواره بیشترین عملکرد دانه و روغن را به خود اختصاص داد و برای کشت در شرایط مواجه با کمبود آب قابل توصیه است.

The cultivation of winter oilseed rape is characterized by high rates of nitrogen fertilization. This can cause large nitrogen surpluses after seed harvest of oilseed rape. Most of the rapeseed oil is used for the production of biofuels. New regulatory standards in the European Union demand a reduction in greenhouse gas (GHG) emissions from biofuels of 60 % (by 2018) compared to fossil fuels. Energy input to produce mineral nitrogen fertilizer is responsible for a high proportion of GHG emissions in the production chain of rapeseed oil. The environmental aspects and new legislative regulations illustrate the future challenge of maintaining current seed yields while using less nitrogen fertilizer than today. The development of oilseed rape cultivars with improved nitrogen use efficiency is one contribution to cope with this challenge. The use of semi-dwarf oilseed rape types might be a step towards this direction. The aim of this study was to analyze the agronomic performance of semi-dwarf and normal oilseed rape hybrids at low and high nitrogen supply. Several nitrogen related traits were analyzed with regard to nitrogen use efficiency. The genetic mechanisms controlling these agronomic and nitrogen related traits were analyzed by QTL mapping. A population of 150 oilseed rape hybrids, segregating in 75 semi-dwarf and 75 normal hybrids was developed from a DH population. DH lines were generated from the cross 'Alesi-bzh' x 'H30'. 'Alesi-bzh' is a dwarf line carrying the bzh dwarf allel. The DH population is segregating into dwarf and normal type lines. The hybrids were tested in field experiments in Einbeck and Göttingen at low nitrogen supply (without nitrogen fertilization) in 2010/2011. In 2011/2012 and 2012/2013 108 hybrids were tested at the same locations at low and high nitrogen supply. On average, semi-dwarf hybrids produced a significantly higher seed yield (2.4 dt/ha) at low nitrogen supply compared to normal hybrids. At high nitrogen supply both growth types produced similar seed yields with a non-significant difference of 0.2 dt/ha. In general semi-dwarf hybrids formed significantly less straw in all environments than normal hybrids. The combinations of higher or similar seed yields and less straw yield resulted in a higher harvest index of semi-dwarf hybrids at both nitrogen supply levels. Semi-dwarfs had a significantly higher nitrogen utilization efficiency compared to normal hybrids at low and high nitrogen supply. That means they produced more kg seed per kg nitrogen taken up. The difference between the growth types was 2.7 and 1.1 kg seeds per kg nitrogen taken up at low and high nitrogen supply, respectively. Therefore, semi-dwarf hybrids revealed a higher nitrogen use efficiency at both nitrogen levels. The variation in nitrogen uptake efficiency contributed more to genetic variation in nitrogen use efficiency than variation in nitrogen utilization efficiency. QTL mapping identified a QTL on linkage group (LG) A06 with pleiotropic effects on seed yield, straw yield, harvest index and nitrogen use efficiency at low and high nitrogen supply. Due to the position of the QTL it is most likely the effect of the dwarf gene Bzh itself. Another QTL with pleiotropic effects on seed yield, harvest index and nitrogen use efficiency was identified on LG A07 at low nitrogen supply. Based on the results of the present study semi-dwarf hybrids produce higher seed yields and show a higher nitrogen use efficiency than normal type hybrids, especially at nitrogen deficient conditions.

Pseudomonas putida CR30RNS (pADPTel) is an antibiotic-resistant strain with a recombinant plasmid that confers resistance to tellurite and the ability to catabolize atrazine. The survival of this strain as well as its ability to transfer genes for atrazine degradation and tellurite resistance to indigenous soil bacteria were tested in both fallow soil and canola (Brassica napus) rhizosphere by the use of parallel field and laboratory releases. Culturable CR30RNS (pADPTel) were enumerated in field and microcosm soils at 7- to 14-day intervals over 49 d. Strain CR30RNS (pADPTel) survived for up to 7 weeks in microcosm soils at a density of 10(4) CFU/g soil, whereas in field soils the population declined to 10(3) CFU/g soil by the fourth week. In contrast, when CR30RNS (pADPTel) was introduced into the soil as a seed coating of canola (B. napus 'Karoo'), the bacterium established at higher cell densities in the rhizosphere (10(6)-10(5) CFU/g fresh root mass), with no subsequent decrease in numbers. The presence of selective pressure (i.e., atrazine) had no significant effect on the survival of CR30RNS (pADPTel) in either field or microcosm soils. One year postinoculation field sites were examined for the presence of CR30RNS (pADPTel) and no evidence of culturable parental cells was observed when samples were plated onto selective media. However, the atzC and telAB gene segments were amplified from the field soils at that time. Under laboratory conditions, indigenous soil bacteria were capable of receiving and expressing the engineered plasmid construct at frequencies ranging from 1 to 10(-3) transconjugants per donor. However, no plasmid transfer to indigenous soil bacteria was detected in the field or microcosm soils regardless of the presence of canola rhizosphere and (or) the application of atrazine. Our results show that the survival and population size of P. putida CR30RNS (pADPTel) might be sufficient for degradation of environmental pollutants but that the transfer frequency was too low to be detected under the conditions of this study.

Crop management for optimal low-linolenic rapeseed oil production—Field experiments and modelling

ABSTRACTThe short-term economic benefit has in recent years prompted farmers to grow oilseed rape (OSR) (Brassica napus L.) and thus the frequency of this crop increased in German crop rotations. Here, we investigate the impact of high-intensity OSR crop rotations on yield, yield formation, and blackleg disease (Leptosphaeria maculans) in a rotation experiment in the Hercynian dry region of Central Germany over two seasons (2014/2015 – 2015/2016). The preceding crop combinations compared were winter wheat (WW) (Triticum aestivum L.)-WW, WW-OSR, OSR-OSR, and an OSR monoculture. Furthermore, the fertilizer treatments 120 kg N ha−1 and 180 kg N ha−1 were analyzed.Higher OSR cropping intensity decreased seed yields, however, with a variation among years and oil yield was highest when OSR was following WW-WW over both years. Minor differences were observed among the yield components, but significantly less pods per m2 were developed in a long-term OSR monoculture. The disease assessment clearly showed an increased blackleg incidence and severity when OSR was grown successively.Results of our study emphasize that high-intensity OSR production will very likely be unsustainable over the long term associated with yield losses and increased infestation levels of blackleg disease.

Utilizing comprehensive decision analysis methods to determine an optimal planting pattern and nitrogen application for winter oilseed rape

Rape (Brassica napus L.) is an essential source of edible oil. The growing demand for rapeseed oil seeks to devise nutrient management strategies to lessen the gap between actual and potential yields. A field experiment was investigated at MRCFC, SKUAST-Kashmir, focusing on the best nutrient management practice for realizing higher yield in Brassica napus, using the nutrient omission plot technique. The yield and yield components of oil seed rape responded significantly to nutrient omissions. Treatments comprising NPKS + FYM, NPKS, NPK, NP, PK, NK, and control with three replications were carried out in randomized block design. Significantly, the highest seed yield of 1250 kg ha−1 was registered with NPKS + FYM, with a yield superiority of 143% over control. In terms of yield attributes, the number of pods plant−1 was the key contributor to yield. Response toward the nutrients followed the order of N > P > S > K. Application of FYM was observed to increase the efficiency of accompanying nutrient particularly for P (6.6%). Combined application of the nutrients leads to improvement in the nutrient efficiency of major nutrients evaluated in terms of agronomic efficiency (AE), physiological efficiency, and apparent nutrient recovery (ANR) efficiency. Based on the outcome of the results, balanced application of chemical fertilizers in combination with FYM seems to be pivotal for harnessing the potential of individual nutrients toward achieving higher yield in Brassica napus.

Management of winter cover crop residues under different tillage conditions affects nitrogen utilization efficiency and yield of eggplant (Solanum melanogena L.) in Mediterranean environment

Three-year field experiments were conducted to investigate the effects of ridge film mulching plus furrow planting (RFMF) and traditional flat planting (FP) on the seed quality, oil yield and nitrogen-use efficiency of winter oilseed rape (Brassica napus) and to determine the optimal rate of nitrogen (N) application under the two planting patterns. Six N rates, 0, 60, 120, 180, 240 and 300 kg N ha−1, were applied under both patterns. RFMF significantly increased seed yield, oil yield, N agronomic efficiency (NAE) and N partial factor productivity (NPFP) by 15.5–43.5%, 18.0–48.3%, 2.1–70.6% and 17.9–48.2% respectively, compared with FP. The optimal N application rates were 235 and 218 kg N ha−1 under RFMF and FP, respectively. In conclusion, RFMF could be adopted with N rate of 235 kg N ha−1 for the cultivation of winter oilseed rape in northwest China to improve shoot nutrient uptake, oil yield and N use efficiencies.

A field experiment was conducted at the Punjab Agricultural University Ludhiana during rabi 2016-17 to study the effect of nitrogen (N) application dose and time on N uptake pattern, protein and oil yield and oil quality of canola oilseed rape (Brassica napus) under different sowing dates. The treatments comprised three sowing dates (15 October, 30 October and 15 November) in the main plots and seven combinations of dose (100 and 125 kg/ha) and time of application of N (two or three splits) in sub plots. Loamy sand soil of experimental field was low in organic carbon and available N in the upper 15 cm soil profile. The test variety GSC 7 was sown at spacing of 45 cm x 10-12 cm. Delay in sowing significantly reduced the N content and uptake by canola oilseed rape at all growth stages in different plant parts as well as in seed and stover at maturity except N content in stem at 80 DAS. The highest oil yield (941 kg/ha) obtained with 125 kg/ha of N applied as 50 kg at sowing + 50 kg at initiation of stem elongation + 25 kg at initiation of flowering was at par with application of 125 and 100 kg/ha of N in two equal splits at sowing and initiation ofstemelongation. The highest protein yield (738 kg/ha) obtained with 125 kg/ha of N applied in three splits (50 + 50 + 25) was significantly higher than all other treatments. The highest oil yield produced by 15 October sown crop with application of 125 kg/ha of N in three splits (1056 kg/ha) was 7.3% and 40.4%% higher than application of 100 kg/ha of N in two equal splits and 6.7% and 35.9% higher than 125 kg/ha of N in three splits in 30 October and 15 November sown crop, respectively. Fatty acid composition of oil was not influenced by sowing dates and N scheduling.

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