Oriental Mustard Research Articles

Influence of environmental factors on seed germination and seedling emergence of Oriental mustard (Sisymbrium orientale)

The effects of environmental factors on seed germination and seedling emergence of Oriental mustard were studied in laboratory and field experiments. Seed germination was stimulated by light; however, some germination occurred in the dark. In light/dark, potassium nitrate at 0.02 M stimulated germination of 1-mo-old seed to a maximum level of 45% as compared with the control (18%). Oriental mustard germination was inhibited by high levels of salt and osmotic stress. Seed germination was greater than 50% over a pH range of 4 to 10. Seedling emergence of 4- to 5-mo-old seeds was highest when present on the soil surface (70%) but declined with depth, and no seedlings emerged from a soil depth of 10 mm. In the field, seedling emergence was greater under no-till than minimum tillage systems.

Seedling recruitment pattern and depth of recruitment of 10 weed species in minimum tillage and no-till seeding systems

Differences in periodicity and depth of weed seedling recruitment due to agronomic management practices, such as reduced tillage, have implications for weed competitive ability and management strategies. Periodicity and depth of seedling recruitment of 10 different weed species was measured in the field in 2004 and 2005. The seedling recruitment of rigid ryegrass, threehorn bedstraw, and wild radish seedlings was higher under minimum tillage than under no-till scenarios. In contrast, the seedling recruitment of Oriental mustard, annual sowthistle, squirreltail fescue, little mallow, and turnipweed was higher under the no-till system. The seedling recruitment of wild oat and African mustard was not influenced by the tillage system. The mean seedling recruitment depth of wild oat, rigid ryegrass, threehorn bedstraw, wild radish, and turnipweed was greater under minimum tillage than under the no-till system. These weeds are able to emerge from deeper in the soil profile. In contrast, the seedling recruitment depth under minimum-tillage and no-till systems was similar for African mustard, Oriental mustard, annual sowthistle, little mallow, and squirreltail fescue. These are all small-seeded species, which failed to emerge from deeper depths under either tillage system. In addition, all of these species except African mustard showed higher total seedling recruitment under the no-till system. Results of this study will facilitate weed-control timing decisions and provide validation data for weed seedling recruitment models.

TIME AND TEMPERATURE EFFECTS ON DEGRADATION OF ISOTHIOCYANATES IN BIOFUMIGATION SYSTEMS

Biofumigation is an alternative to traditional methods of soil sterilization such as methyl bromide. Biofumigation utilizes volatile, pesticidal compounds in soil incorporated plant material from various Brassica species. Three experiments were conducted to study the degradation of allyl isothiocyanate (AITC) generated from the breakdown of glucosinolates present in Oriental mustard (Brassica juncea L. Czerniak). Mustard seed meal was incorporated into a sandy clay loam soil in all experiments. In the first experiment, samples were hydrated and then held in an incubator at 20 ± 0.2 °C. Samples were taken periodically for 7 days or until AITC was not detectable. For the second experiment, hydrated samples were removed from the incubator after 4 hours and 5 mL of ethyl acetate was added. The samples were then placed in a refrigerator at 4 ± 0.2 °C and samples were taken periodically over 77 days. For the third experiment, samples were taken from a strawberry plot experiment grown in a randomized complete block design. Samples were taken and 5 mL of ethyl acetate was added. Then samples were placed into a cooler until returning to the laboratory. The incubator experiment was repeated and showed that the highest concentration of AITC occurred between 2 and 8 hours after hydration. The storage experiment showed a stable relationship between time and AITC degradation. AITC was still present after 77 days. The strawberry plot experiment showed rapid AITC degradation similar to the incubator experiment. Future research will be done to confirm the effects of temperature and glucosinolate content on the amount of allyl isothiocyanate present.

Response of mustard to fertilization, seeding date, and seeding rate in southern Alberta

Yellow mustard (Sinapsis alba L.), brown mustard (Brassica juncea L.), and oriental mustard (B. juncea) have been grown in Alberta since the 1950s, but limited agronomic information specific for this crop is available. The objective of this study was to determine the response of mustard to fertilization, seeding date and seeding rate in southern Alberta. Field experiments were conducted at 20 field sites over a 4-yr period (1999–2002) under irrigated and dryland (fallow and stubble) conditions. Five experiments were conducted with the following treatments: (1) N fertilizer rate (0, 30, 60, 90 and 120 kg N ha-1), (2) urea placement (seed-placed and side-banded urea at rates of 0 to 120 kg N ha-1), (3) P fertilizer rate (0, 6.5, and 13.1 kg P ha-1), (4) S fertilizer rate (0, 10 and 20 kg S ha-1), and (5) seeding date (three dates at approximately 10-d intervals) and seeding rate (target plant densities of 75, 125, 175, 225, and 300 plants m-2). Experiment 1 was conducted with yellow mustard (AC Pennant), oriental mustard (Forge), brown mustard (Commercial Brown) and canola (Q2) (Brassica napus L.), while the remaining experiments were only conducted with yellow mustard. For maximum seed yield, mustard required 95 kg of available N Mg-1 of potential seed yield. Potential yields were closely related to available moisture, increasing 7 to 8 kg ha-1 for every mm increase in available moisture above a minimum moisture requirement of 90 mm. Seed-placed urea reduced plant stand at rates as low as 30 kg N ha-1 and reduced seed yield at rates of 60 to 120 kg N ha-1. Fourteen of 20 sites had a greater than 3% positive yield benefit due to P fertilizer. Mustard did not benefit from S fertilizer application. Delay in seeding by 3–4 wk, compared with seeding in late April to mid-May, reduced seed yield of yellow mustard by an average of 37%. Seed yield increased with seeding rate, but the maximum gain in seed yield due to high seeding rates was only 200 kg ha-1, with significant increases obtained only under very dry conditions. Early seeding and adequate N fertility were the most important agronomic practices for achieving high yields of mustard in southern Alberta. Key words: Sinapsis alba, Brassica juncea, yield, oil, nitrogen, phosphorus, sulfur, water-use efficiency

Production of mustard protein isolates from oriental mustard seed (Brassica juncea L.)

AbstractA membrane‐based process to produce protein isolates from seeds of oriental mustard (Brassica juncea) was developed by modifying a method originally developed for rapeseed. The optimized process consisted of extraction at pH 11, ultrafiltration with concentration factor 4, diafiltration with diavolume 3, and precipitation at pH 5. The process, based on defatted oriental mustard seed containing 45–50% protein, recovered 81% of the protein in useful products: 47.3% in precipitated protein isolate (PPI), 3.8% in soluble protein isolate (SPI), and 13% in meal residue. Mass yields were 21.9% in PPI, 2.8% in SPI, and 38.4% in meal residue. The losses in the system included ∼10% loss of nonprotein nitrogen, and <9% into permeate and transfer losses. The PPI compared favorably with soy protein isolate in typical meat products in terms of color, texture, and flavor. The work confirms that oriental mustard is a potentially useful source of edible protein.

Manure Slurry-Enriched Micro-Site Seeding of Biosuppressive Covers

There is increasing interest among growers in novel establishment systems for cover crops that can rehabilitate and protect soil. Cropping intensification has led to yield declines, compacted and poor quality soil, and increased pest problems. Cover crops in the Brassica (mustard) family offer benefits in soil conservation, improvement in soil quality, reduction in nitrate leaching, and suppression of certain pests and soil borne fungal diseases. Establishment of cover crops by conventional methods following harvest presents a significant challenge as soil is generally dry, compacted, uneven, and far from an ideal environment for seed germination. An alternative method, manure slurry-enriched micro-site seeding, incorporates aeration tillage, manure application, and seeding in a single operation. The objective of this work was to evaluate manure slurry-enriched micro-site seeding of cover crops by assessing stand establishment and biomass yield of oilseed radish and oriental mustard. The species were chosen for contrasting seed size, thus allowing evaluation of how small versus medium seeded brassica respond to aeration tillage, manure application, and seeding done in a single efficient 'manure slurry-enriched micro-site seeding' operation. Results of field trials in 2004 and 2005 were consistent with the new manure slurry seeding process as an efficient and effective cover crop establishment method. Compared to direct-drilling, manure slurry seeded plant stands (plants m-2) were significantly less (a = 0.10) in five of seven comparisons but biomass yields (kg ha-1) were similar because individual plant biomass was up to six times greater with manure slurry seeding. Biomass (aboveground and total) of manure slurry seeded plants was significantly greater in two of seven comparisons and there were no instances when the conventionally seeded crops yielded significantly more than the manure slurry seeded crops. Seed size did not affect the success of the manure slurry seeding method.

Enhanced nitrogen mineralization in mowed or glyphosate treated cover crops compared to direct incorporation

Information on how management by mowing and herbicide alter residue quality and nitrogen (N) inputs would be valuable to improve prediction of N availability. Mowing and glyphosate application are widely used by growers to limit cover crop growth and facilitate incorporation. A mixture of cover crops, hairy vetch (Vicia villosa L.), oriental mustard (Brassica junceaL.) and cereal rye (Secale cerealeL.), was investigated as a means to improve soil quality and optimize N availability. There is limited information on how mowing or glyphosate application influence cover crop decomposition and N mineralization from these heterogeneous residues. A rye cover crop was grown in the field over the winter and transferred to containers as an intact soil profile to conduct a greenhouse study. Management treatments (mowing and glyphosate) were imposed eight days before incorporation. Plant and soil N dynamics were monitored. The experiment was repeated with the addition of a tri-mixture cover crop. Inorganic NO3− in bare soil ranged from 6 to 10 μg N g soil−1 over 39 days. Similar or lower levels of soil NO3− were observed after rye residue incorporation, from 2 to 6 μg N g−1; consistent with N-immobilization. Application of untreated, mixed cover crop residues generally was associated with higher levels of soil inorganic NO3−, from 3 to 11 μg N g−1. For both rye and mixed residues, management by mowing or glyphosate enhanced N mineralization by 10 to 100%, compared to untreated residues. At the same time, application of mowing or glyphosate 8 days before cover crop incorporation seemed to reduce the amount of residues by about half compared to untreated controls. Belowground biomass was reduced more than aboveground, although recovery of senescent roots may have been incomplete. Management by glyphosate or mowing enhanced soil inorganic N availability in the short-term while simultaneously reducing carbon and N inputs.

Registration of ‘Pacific Gold’ Oriental Condiment Mustard

Crop ScienceVolume 44, Issue 6 p. 2271-2272 Registrations Of Cultivar Registration of ‘Pacific Gold’ Oriental Condiment Mustard J. Brown, Corresponding Author J. Brown jbrown@uidaho.edu Department of Plant, Soil and Entomological Sciences, University of Idaho, Moscow, ID, 83844-2339Corresponding author (jbrown@uidaho.edu)Search for more papers by this authorJ.B. Davis, J.B. Davis Department of Plant, Soil and Entomological Sciences, University of Idaho, Moscow, ID, 83844-2339Search for more papers by this authorD.A. Brown, D.A. Brown Department of Plant, Soil and Entomological Sciences, University of Idaho, Moscow, ID, 83844-2339Search for more papers by this authorL. Seip, L. Seip Department of Plant, Soil and Entomological Sciences, University of Idaho, Moscow, ID, 83844-2339Search for more papers by this authorT. Gosselin, T. Gosselin Department of Plant, Soil and Entomological Sciences, University of Idaho, Moscow, ID, 83844-2339Search for more papers by this author J. Brown, Corresponding Author J. Brown jbrown@uidaho.edu Department of Plant, Soil and Entomological Sciences, University of Idaho, Moscow, ID, 83844-2339Corresponding author (jbrown@uidaho.edu)Search for more papers by this authorJ.B. Davis, J.B. Davis Department of Plant, Soil and Entomological Sciences, University of Idaho, Moscow, ID, 83844-2339Search for more papers by this authorD.A. Brown, D.A. Brown Department of Plant, Soil and Entomological Sciences, University of Idaho, Moscow, ID, 83844-2339Search for more papers by this authorL. Seip, L. Seip Department of Plant, Soil and Entomological Sciences, University of Idaho, Moscow, ID, 83844-2339Search for more papers by this authorT. Gosselin, T. Gosselin Department of Plant, Soil and Entomological Sciences, University of Idaho, Moscow, ID, 83844-2339Search for more papers by this author First published: 01 November 2004 https://doi.org/10.2135/cropsci2004.2271aCitations: 19 Registration by CSSA. Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume44, Issue6November–December 2004Pages 2271-2272 RelatedInformation

Phytotoxicity and persistence of flucarbazone-sodium in soil

Abstract Flucarbazone-sodium, a new herbicide, exhibits high bioactivity at low concentrations. To elucidate potential carryover and crop injury, the behavior of flucarbazone in six Western Canadian soils was studied in the laboratory. A sensitive bioassay was developed for the detection of flucarbazone. Of five crops tested, oriental mustard showed the highest degree of root and shoot inhibition from the presence of flucarbazone in soil. Flucarbazone concentrations as low as 1 μg kg−1 were detected by the mustard root inhibition method. This bioassay was used to examine phytotoxicity and persistence of flucarbazone. Phytotoxicity was related to soil organic carbon content. Concentrations corresponding to 50% inhibition (I50 values) were estimated after fitting the data to a log-logistic model. I50 estimates ranged from 6.0 to 27.5 μg kg−1 for soils containing 1.1 to 4.3% organic carbon, respectively, and were correlated (R = 0.979) with percent organic carbon in the investigated soils. Persistence of flu...

Canola and mustard response to short periods of temperature and water stress at different developmental stages

Seed yield of Brassica crops in semiarid environments can be increased by minimizing the crops’ exposure to high temperature and water stress that often occurs during the growing season. A growth chamber study was conducted to determine the effect of short periods of high temperature and water stress at different developmental stages on seed yield and yield components of Brassica crops. Two canola-quality Brassica juncea ‘PC98-44’ and ‘PC98-45’, a Brassica napus canola ‘Quantum’, and a B. juncea oriental mustard ‘Cutlass’ were grown under 20/18°C day/night temperatures with photoperiod of 16/8 h light/dark. High (35/18°C) and moderate (28/18°C) temperature stress was imposed for 10 d during bud formation, flowering, and pod development. Low (90% available water) and high (50% available water) water stress was imposed in combination with the temperature treatments. On average, the 35/18°C stress reduced main stem pods by 75%, seeds pod-1 25%, and seed weight 22% from the control. Seed yield per plant was reduced by 15% when plants were severely (35/18°C) stressed during bud formation, 58% when stressed during flowering, and 77% when stressed during pod development. Plants stressed at earlier growth stages exhibited recovery, whereas stress during pod development severely reduced most of the yield components. Effect of water stress on seed yield was minimal regardless of crop developmental stage. The four Brassica cultivars responded similarly to water stress. In response to temperature stress, B. juncea produced greater number of pods per plant but had a great rate of pod infertility than B. napus. Seed yield of B. juncea in semiarid environments can be increased by improving pod fertility, whereas the seed yield of B. napus can be increased by improving pod pro duction and retention. Key words: Oilseed, yield components, Brassica species, moisture.

Comparing Brassica oilseed crop productivity under contrasting N fertility regimes in the semiarid northern Great Plains

We compared the growth and yield of five Brassica spp. genotypes [two B.juncea (L.) Coss., two B. napus L. and one B. rapa L.] in 11 environments spanning two degrees of latitude and longitude in southern Saskatchewan in 1996–1998. All entries were managed with three levels of N fertility at each site. Plant height for the canola-quality B. juncea breeding line J904316 was 21% greater than the mean of the other genotypes, but shoot biomass did not differ for the same comparison. Cutlass Oriental mustard consistently yielded greatest across all environments while the yield of J904316 was highly variable among environments. The mean seed yield of Cutlass was 12% greater than the highest-yielding B. napus cultivar and 32% greater than the B. rapa cultivar, and had a greater harvest index. Earlier genotypes yielded greater than late-flowering and maturing genotypes within B. juncea and B. napus, but the earliest genotype, Maverick (B. rapa), yielded lower than all other genotypes. All Brassica spp. genotypes were responsive to N fertilization, and high total available N (average = 109, range = 91 to 131 kg N ha-1) was generally required to maximize seed yield, but not shoot biomass, under the conditions of this study. Pod density was the primary yield component influenced by N level. This study illustrates the potential adaptive advantage of B. juncea on the semiarid northern Great Plains. Key words: Brassica, canola, genotype, mustard, N fertility, semiarid, northern Great Plains

Direct and simultaneous analysis of sinigrin and allyl isothiocyanate in mustard samples by high-performance liquid chromatography.

A reversed-phase HPLC method for the simultaneous determination of the glucosinolate sinigrin and its major degradation product allyl isothiocyanate (AITC) was developed and used for direct analysis of aqueous extracts from Oriental mustard (Brassica juncea L.) related materials (ground and cracked seeds, powders, and bran) and from soil samples. The lowest detection limit was 0.1 microg/mL for both sinigrin and AITC). The developed method was used to trace the degradation of sinigrin to AITC in aqueous extracts. One of the major advantages of this method is the complete estimation of sinigrin content. The simultaneous analysis of both sinigrin and AITC in a single run avoided the underestimation caused by separate analyses.

Suitability of Undersown Sweetclover as a Fallow Replacement in Semiarid Cropping Systems

The negative effects of tilled fallow on soil quality may be reduced by utilizing legume green manure crops. A study was conducted to determine the suitability of biennial sweetclover [Melilotus officinalis (L.) Lam.] as a partial fallow replacement on the northern Great Plains. Sweetclover undersown in field pea (Pisum sativum L.), flax (Linum usitatissimum L.), or oriental mustard [Brassica juncea (L.) Coss.] and killed in June of the subsequent fallow year attained shoot biomass yields of 3110 to 5370 kg ha−1, depending on the year and companion crop with which it was grown. Living sweetclover plus its residues after being killed provided excellent ground cover to reduce the risk of erosion throughout the 20‐mo fallow period. Sweetclover compared to tilled fallow reduced soil water content at the time of seeding spring wheat (Triticum aestivum L.) in 2 of 3 yr. Available soil N in April before seeding spring wheat was 16 to 56 kg ha−1 greater in sweetclover green manure than in fallow treatments. Wheat yields were 47 to 75% greater in the sweetclover than in the fallow treatments. However, the many positive attributes of sweetclover green manure must be weighed against potential reductions in companion crop yield. Undersown sweetclover reduced flax yield in 1 of 3 yr and mustard and field pea yield in 2 of 3 yr, with yield losses ranging from 10 to 55%. Additional research is needed to determine agronomic practices that would reduce competitive interactions between sweetclover and its companion crop.

Factors Affecting the Toxicity of MON 37500 Residues to Following Crops1

MON 37500 was registered in 1999 for weed control in wheat and has the potential to injure following crops. Therefore, growth chamber experiments were conducted to determine the effect of soil properties on the phytotoxicity of MON 37500 residues, the relative tolerance of several potential rotational crops, and the joint effect of MON 37500 residues plus other herbicide residues on a susceptible crop. In 13 Alberta soils, the concentrations of MON 37500 and triasulfuron that reduced canola and barley dry matter by 50% (GR50) were correlated with soil organic matter (OM) and pH. The relationship that best described the effect of soil organic matter on GR50 for each herbicide–crop combination was GR50 = a b(OM)2. There was no significant improvement in r2 when pH and clay content were included in the equation. For soils with 2 and 10% OM content, predicted GR50 values for canola in MON 37500–treated soil are 2 and 26 ηg/g soil, respectively. Little injury to following canola is predicted in soils with OM contents > 4.5%. At similar concentrations, following crops such as canola, flax, lentil, and oriental mustard are predicted to be injured less by MON 37500 than by triasulfuron. The effect of combined residues of MON 37500 with triasulfuron, imazethapyr, or metsulfuron should be additive.Nomenclature: Imazethapyr; metsulfuron; MON 37500, 1-(4,6-dimethoxypyrimidin-2-yl)-3-(2-ethanesulfonylimidazo[1,2-a]pyridine-3yl)sulfonylurea; triasulfuron; barley, Hordeum vulgare L.; canola, Brassica napus L.; flax, Linum usitatissimum L.; lentil, Lens culinaris Medic; oriental mustard, Brassica juncea L.; wheat, Triticum aestivum L.Additional index words: Crop rotation, herbicide residue, pH, soil organic matter.Abbreviations: GR50, growth measurement corresponding to 50% of the untreated; OM, soil organic matter.

Response of three Brassica species to high temperature stress during reproductive growth

The effect of short periods of high temperature stress on the reproductive development and yield of three Brassica species were studied in a growth chamber experiment conducted for 2 yr. Two genotypes from Brassica juncea L. and one each from B. napus L. and B. rapa L. were grown under day/night temperatures of 20/15 °C till early flowering or early pod development, subjected to high temperature stress of 28/15 °C or 35/15 °C for 7 d and then allowed to recover at 20/15 °C. Species differed in optimum temperatures, with B. juncea and B. rapa having higher optimum temperature than B. napus. Dry matter was unaffected by moderate temperature stress, while it was reduced by high temperature stress. The 35/15 °C treatment was injurious to reproductive organs at different developmental stages of all three species. High temperatures at flowering affected yield formation more than high temperature at pod development. On the main stem, mean seed yield reduction due to heat stress was 89%, but partial compensation by pods on the branches reduced mean per-plant seed yield decrease to 52%. Reduction in fertile pods (not total pod number), thousand seed weight and seeds per pod were responsible for the reduced seed yield. Brassica rapa was more sensitive to heat stress than B. napus and B. juncea. Although observation did not indicate the exact developmental phase when the reproductive organs were susceptible to heat stress, pods that passed a critical threshold developmental phase tolerated heat stress, which explained the smaller effect of high temperature stress at pod development. A direct temperature effect on reproductive organs appeared to be responsible for the reduction in yield. All genotypes began to recover from the stress by continuing flowering after returning to 20/15 °C. Brassica napus was least able to recover from severe stress at flowering, as evidenced by the formation of many abnormal pods during recovery. Per-plant yield response of canola-quality B. juncea line J90-4316 was similar to oriental mustard Cutlass. Thus, heat stress effect depends on the growth stage of canola and mustard and Brassica species differ in heat stress response. Key words: Brassica species, napus, rapa, juncea, heat stress, yield, pod number

Use of anion-exchange membrane extraction for the high-performance liquid chromatographic analysis of mustard seed glucosinolates.

A new one-step extraction using anion-exchange membranes for the HPLC determination of glucosinolates in mustard seeds is reported. The exchange of glucosinolates on the membranes was studied using sinigrin in solutions and sinigrin added as an internal standard to seeds of yellow mustard. By varying time of extraction, membrane size, and sample size, the optimal conditions for maximum glucosinolate recovery were determined and the following procedure was adopted: 0.2 g of ground mustard seeds are heated in 20 mL of boiling water for 5 min. After cooling, samples are transferred to plastic centrifuge tubes, 9-cm(2) membranes are added, and suspensions are shaken on a mechanical shaker for 2.5 h. Glucosinolates are then eluted from the membranes with 25 mL of 1 N KCl by shaking again for 2.5 h. Using this procedure, the sinigrin extraction from solutions and from mustard seeds was linear with 80% recovery. Seeds of yellow, brown, oriental, and Indian mustard were analyzed by this procedure; excellent reproducibility, with coefficients of variation in the range 1.0-4.3% were obtained. This method offers a simple and inexpensive alternative to complicated and tedious procedures for glucosinolate isolation/purification required for chromatographic determinations.

Factors affecting the dissolution and degradation of oriental mustard-derived sinigrin and allyl isothiocyanate in aqueous media.

Sinigrin, the predominant glucosinolate in the oriental mustard Brassica juncea, is mainly degraded upon the enzymatic action of myrosinase under normal conditions to give allyl isothiocyanate (AITC) in an aqueous media. Because AITC is considered to be the principal nematicidal ingredient in B. juncea, its stability in aqueous media is an important issue in achieving efficient nematode control. Pure sinigrin and AITC were found to be relatively stable in buffered water in the pH range of 5.00-7.00 but less stable at pH 9.00. Both sinigrin and AITC were more stable in soil water (supernatant of a 1:1 water/air-dried soil mixture) than in buffered water at the same pH range of 5.00-9.00. Sinigrin dissolved from the mustard bran or ground seed into water very quickly and was degraded by codissolved myrosinase to AITC. The AITC that formed from the degradation of sinigrin was found to be more stable in the soil water than in the buffered water. Buffer capacity was considered to be one of the factors that contributed to the stabilization of AITC in the soil water, but other unknown factors from both bran or seed and soil may also have contributed to the stabilization.

Sexual hybridisation in crosses of cultivated Brassica species with the crucifers Erucastrum gallicum and Raphanus raphanistrum: Potential for gene introgression

Studies were conducted to investigate the crossability of the cultivated Brassica species, Brassica napus (oilseed rape), B. rapa (turnip rape), and B. juncea (brown and oriental mustard), with two related cruciferous weeds that are abundant in certain regions of Canada, Erucastrum gallicum (dog mustard) and Raphanus raphanistrum ssp. raphanistrum (wild radish). Seed was produced without recourse to embryo rescue from all reciprocal crosses except R. raphanistrum × B. juncea. Four hybrid plants were recovered, namely B. napus × E. gallicum, B. napus × R. raphanistrum (two plants), and B. rapa × E. gallicum. The hybrids were characterized by their morphology, RAPD analysis, and cytological examination. The B. rapa × E. gallicum hybrid was extremely vigourous and fertile, and would likely grow in natural habitats. This hybrid produced self-seed and backcrossed readily with the B. rapa parent and, to a lesser extent, with the E. gallicum parent. The B. napus × E. gallicum hybrid was a weak plant, but produced fertile backcross progeny with the E. gallicum parent. The B. napus × R. raphanistrum hybrids were vigourous but mostly sterile. Because of their low vigour and/or sterility, hybrids produced from crosses of B. napus with the cruciferous weeds would not likely be an environmental concern. However, the potential of the B. napus × E. gallicum and B. rapa × E. gallicum hybrids to backcross with E. gallicum may be of concern.

Genotypic variation for competitive ability in spring wheat

AbstractHerbicides are the primary method of weed control for crop production in developed countries. For economic and environmental reasons alternative control strategies are being devised. One of these strategies is the development of competitive crop cultivars. The objectives of this research were to establish whether spring wheat (Triticum aestivum L.) genotypes differed in competitive ability and if those differences were related to specific growth characteristics. Sixteen genotypes of spring wheat were grown under simulated weed competition conditions at Saskatoon, Canada over a 3–year period. Four high and four low tillering genotypes from each of two crosses (Neepawa/M1417 and Ingal/M1417) were studied. Weeds consisted of cultivated oat (Avena saliva cv. ‘Waldern’) and oriental mustard (Brassicajuncea cv. ‘Cutlass’) sown at two densities (48 and 96 seeds/m2 per weed species). Seedling establishment, ground cover, and seed yield for the three species were determined, as was wheat tiller number, spike number, maximum height, leaf area index, leaf orientation, and flag leaf length and size. Significant (P = 0.001) weed rate by genotype interactions involving changes in genotype rank were detected for wheat grain yield, indicating that the 16 wheat genotypes differed in competitive ability. Wheat grain yield reductions averaged over the two weed densities ranged from 45% to 59%. The highest‐yielding genotypes under weed‐free conditions were not necessarily the highest yielding under weedy conditions. Genotypes which suffered smaller yield reductions were more effective in suppressing weed growth. Although competitive genotypes were generally taller than non‐competitive genotypes, other traits such as large seedling ground cover and flag leaf length were associated with wheat yield under competitive conditions.

Enrichment of very-long-chain mono-unsaturated fatty acids by lipase-catalysed hydrolysis and transesterification

Partial hydrolysis of triacylglycerols of high-erucic-acid seed oils from white mustard (Sinapis alba), oriental mustard (Brassica juncea) and honesty (Lunaria annua), catalysed by lipases from Candida cylindracea and Geotrichum candidum, leads to enrichment of erucic acid and other very-long-chain mono-unsaturated fatty acids (VLCMFA) in the acylglycerols (mono-, di- and triacylglycerol) while the C18 fatty acids (oleic, linoleic and linolenic) are enriched in the fatty acid fraction. Partial hydrolysis of the high-erucic-acid triacylglycerols, catalysed by lipases from porcine pancreas, Chromobacterium viscosum, Rhizopus arrhizus and Rhizomucor miehei yields fatty acids with substantially higher levels of VLCMFA, as compared to the starting material, while the C18 fatty acids are enriched in the acylglycerol fraction. Lipases from Penicillium sp. and Candida antarctica are ineffective for the fractionation of either group of fatty acids. Transesterification of the high-erucic-acid triacylglycerols with ethyl, propyl or butyl acetate or with n-butanol, catalysed by the lipase from R. miehei, leads to enrichment of VLCMFA in the alkyl (ethyl, propyl or butyl) esters, whereas the C18 fatty acids are enriched in the acetylacylglycerols and acylglycerols.