Rapeseed

Abstract: This paper reviews the most important biological processes that determine the yield of winter oilseed rape ( Brassica napus L.). Biological yield is the product of growth rate and duration of the growing period, both of which indicate the potential for improvement in yield. Likewise, a greater harvest index leads to a higher seed yield. A brief survey of five recently published rapeseed crop models is given. Most of these models are poor predictors of biomass and yield; there is a lack of information about key physiological processes involved in establishment of the stand, the production of biomass and formation of yield, cessation of growth in winter, flowering and post-anthesis growth. During flowering and pod set, the relation between source and sink regulates the availability of assimilates necessary for seed filling. The most source-limiting process is related to small photosynthetically active area, caused by a drastic decline in the leaf area index from the start of flowering despite a slow increase in the assimilating pod area. To analyse yield, it is necessary to understand the structure of the yield and the primary and secondary components, which determine seed yield. Plant density governs the components of yield and, thus, the yield of individual plants. A uniform distribution of plants per unit area is a prerequisite for yield stability. The number of pods per plant is decisive for seed yield; this trait is ultimately determined by the survival of branches, buds, flowers and young pods rather than by the potential number of flowers and pods. Seed number per pod is correlated with pod length. It is, therefore, concluded that pod length is a suitable trait for indirect selection in plant breeding.

Abstract: Molecular gene transfer techniques have been used to engineer the fatty acid composition of Brassica rapa and Brassica napus (canola) oil. Stearoyl-acyl carrier protein (stearoyl-ACP) desaturase (EC 1.14.99.6) catalyzes the first desaturation step in seed oil biosynthesis, converting stearoyl-ACP to oleoyl-ACP. Seed-specific antisense gene constructs of B. rapa stearoyl-ACP desaturase were used to reduce the protein concentration and enzyme activity of stearoyl-ACP desaturase in developing rapeseed embryos during storage lipid biosynthesis. The resulting transgenic plants showed dramatically increased stearate levels in the seeds. A continuous distribution of stearate levels from 2% to 40% was observed in seeds of a transgenic B. napus plant, illustrating the potential to engineer specialized seed oil compositions.

Abstract: Phoma stem canker (blackleg), caused by Leptosphaeria maculans, is an important disease on oilseed rape (canola, rapeseed, Brassica napus, Brassica juncea, Brassica rapa) causing seedling death, lodging or early senescence in Australia, Canada and Europe, but not in China. The two forms of L. maculans (A group and B group) that occur on oilseed rape are now considered to be separate species. The epidemiology and severity of phoma stem canker differs between continents due to differences in the pathogen population structure, oilseed rape species and cultivars grown, climate and agricultural practices. Epidemics are most severe in Australia, where only the A group occurs, and can be damaging in Canada and western Europe, where both A and B groups occur, although their proportions vary within regions and throughout the year. Epidemics are slight in China, where the A group has not been found. Dry climates (Australia, western Canada) lengthen the persistence of infected debris and may synchronize the release of airborne ascospores (after rain) with seedling emergence. L. maculans spreads from cotyledon and leaf infections down petioles to reach the stem, with infections on cotyledons and leaves early in the season producing the most damaging stem cankers at the stem base (crown). Development of both crown cankers and phoma stem lesions higher up stems is most rapid in regions with high temperatures from flowering to harvest, such as Australia and Canada. Breeding for resistance (genetic, disease escape or tolerance), stubble management, crop rotation and fungicide seed treatments are important strategies for control of phoma stem canker in all areas. Fungicide spray treatments are justified only in regions such as western Europe where high yields are obtained, and accurate forecasts of epidemic severity are needed to optimize their use.

Abstract: The tocopherol and tocotrienol (i.e. tocol) and plant sterol contents of 14 vegetable and 9 industrial fats and oils available on the Finnish market in 2005 were determined using NP-HPLC with fluorescence detection (tocols) and GC-FID (plant sterols). Best sources of α-tocopherol were wheat germ (192 mg/100 g) and sunflower oil (59 mg/100 g). Oils richest in γ-tocopherol were camelina (72 mg/100 g), linseed (52 mg/100 g) and organic rapeseed oil (51 mg/100 g). Total tocol contents were between 4.2 mg/100 g (coconut fat) and 268 mg/100 g (wheat germ oil). Plant sterol contents ranged from 69 mg/100 g in a frying fat to 4240 mg/100 g in wheat germ oil. Organic rapeseed oil, the second best source of plant sterols, contained 887 mg/100 g. The variations of the total tocol and sterol contents in 10 rapeseed oil sub-samples analysed separately were 9.7% for tocols and 9.9% for sterols in refined rapeseed oil, and 6.3% for tocols and 4.2% for sterols, respectively, in cold-pressed rapeseed oil. In addition to the target compounds, plastochromanol-8 could be determined in all plant-based samples with contents ranging from 0.13 (walnut oil) to 18 mg/100 g (linseed oil). The lignans sesamin and sesamolin could be identified in sesame oil.

Abstract: This report presents the findings from a study of the life cycle inventories for petroleum diesel and biodiesel. It presents information on raw materials extracted from the environment, energy resources consumed, and air, water, and solid waste emissions generated. Biodiesel is a renewable diesel fuel substitute. It can be made from a variety of natural oils and fats. Biodiesel is made by chemically combining any natural oil or fat with an alcohol such as methanol or ethanol. Methanol has been the most commonly used alcohol in the commercial production of biodiesel. In Europe, biodiesel is widely available in both its neat form (100% biodiesel, also known as B1OO) and in blends with petroleum diesel. European biodiesel is made predominantly from rapeseed oil (a cousin of canola oil). In the United States, initial interest in producing and using biodiesel has focused on the use of soybean oil as the primary feedstock mainly because the United States is the largest producer of soybean oil in the world. 170 figs., 148 tabs.