Efficacy Of Tillage Weed Control For Vegetable Brassicas

Weed control is a major reason normally advocated for soil tillage. The use of primary cultivation, ploughing and secondary cultivation, discing and harrowing eliminates emerging annual weeds and suppresses perennial weeds. Ploughing buries about 80 of surface weed seeds and only returns about 40 to the surface. It also brings perennial rhizomes and tillers to the surface, allowing them to be killed by desiccation or freezing. Conservation (limited) tillage or non-tillage systems have been...

Limited Availability Of Herbicides For Brassica Crops

In the USA, a collaborative project was established in 1963, known as the IR-4 Project (Inter-regional Research Project Number Four). Collaboration has been established between state agricultural research stations, the US Department of Agriculture-Cooperative States Research Service (USDA-CSRS), chemical manufacturers and growers organizations to identify and register herbicides for use with speciality crops such as the brassicas (Hopen, 1995 Baron et al., 2002). This initiative was driven by...

The Effects Of Weeds Competition

The agronomist defines weeds as 'plants which interfere adversely with the production aims of the grower' (Spitters, 1990). Weeds affect crops by reducing crop growth and yield, mainly due to competition that limits resources such as light, water and nutrients reducing the financial value of the harvested product, either by contaminating the produce or by diminishing its quality and hampering husbandry practices, especially harvesting operations, thereby increasing costs. Weeds reduce the...

Integrated crop management ICM

The husbandry processes of soil cultivation, addition of fertilizers, transplanting, application of agrochemicals and irrigation are now regarded as a continuum. Collectively, they are aimed at achieving the highest possible quality in the product compatible with minimum use of resources, and are summarized as 'integrated crop management (ICM) (this is referred to in several previous chapters, notably Chapters 6 and 7). The formulation of standardized husbandry protocols well in advance of crop...

Calabrese Green Broccoli Brassica Oleracea Var Italica

Agronomically, broccoli (calabrese) growth may be divided into the two phases first, from drilling or transplanting to spear initiation and, secondly, from initiation to maturity. Predicting the duration of both growth periods has vital relevance to crop scheduling, for land occupancy and hence rotational growing, and for adherence to marketing schedules. Leaf number defines the stage of crop growth. This is firstly related to genotype and secondarily increases with later planting dates, partly...

The implications of climate change on cauliflower

Analyses of potential effects of global climate change suggest that an elevation of +1 C at temperatures below 15.5 C will reduce the time taken to cauliflower curd initiation. Where temperatures are above 15.5 C, then time to curd initiation will be likely to increase since curd initiation is reduced at elevated temperatures, hence crop duration from plantings later in the season is likely to be extended. Elevation of carbon dioxide content increases curd weight (biomass) especially dry matter...

Acknowledgements Copyrights

The United Nations Food and Agriculture Organisation (UNFAO), Rome. Fig. 1.3. Professor P.H. Williams, University of Wisconsin, and SpringerVerlag GmbH, Heildeberg. Fig. 1.4. New York Botanic Garden. Fig. 1.5. Ms Joy Larcom and John Murray, London. Fig. 1.6. Dr M.H. Dickson, Cornell University. Fig. 2.1. Dr M.H. Dickson, Cornell University. Fig. 2.2. Dr M.H. Dickson, Cornell University. Fig. 2.3. Dr M.H. Dickson, Cornell University. Fig. 2.4. Dr M.H. Dickson, Cornell University. Fig....

Assaying Selfincompatibility

The level of self-incompatibility can be assessed by the number of seed produced after a self- or cross-pollination, but this takes at least 60 days. Fluorescent microscopy techniques readily display those pollen tubes that have penetrated the style, and this provides a direct measure of incompatibility which can be completed within 12-15 h. Aniline blue stain accumulates in the pollen tubes and fluoresces when irradiated with ultraviolet light. With appropriate light filters under a...

Seed Quality

Seed that attains maximum viability and vigour is physiologically mature, and thereafter deterioration begins Powell and Matthews, 1984 . Seed should be harvested ideally when it has attained physiological maturity and has not started to deteriorate. Reaching greatest dry mass is generally correlated with optimum maturity and quality as quantified by maximum germination in controlled tests. This state may not correlate with the maximum seedling vigour under field conditions. For growers of...

Vegetable Brassicas and Related Crucifers

Dixon Centre for Horticulture and Landscape, School of Biological Sciences, University of Reading, UK formerly at The Department of Bioscience, The Royal College, University of Strathclyde, Glasgow, UK CABI is a trading name of CAB International CABI North American Office 875 Massachusetts Avenue 7th Floor Cambridge, MA 02139 USA Nosworthy Way Wallingford Oxfordshire OX10 8DE UK Tel 44 0 1491 832111 Fax 44 0 1491 833508 E-mail cabi cabi.org Tel 1 617 395 4056 Fax 1 617 354 6875...

Preface

Brassica vegetables serve mankind as they have done for millennia as sources of food, fodder and forage. The quiet mundanity of rural cabbage yards belies the botanical miracles taking place within them by these arch-exponents of genotypic and phenotypic diversity and flexibility. Brassicas provide one of the finest examples of convergent evolution in the horticultural forms of the European Brassica oleracea and Oriental B. rapa. These mirror each other in a diverse spectrum of fresh foodstuffs...

Curd colour

Flower And Crop Production

The most desired colour in cauliflower is a white or cream curd. In many cauliflowers, if the curd is exposed to the sun, it will turn brownish yellow this is especially so for the Snowball type. Cauliflowers are protected from the sun, either by wrapping the leaves over the head and tying them, or by developing plants with long leaves, which protect the curd from exposure. The upright leaf character is partially dominant, with a heritability of 67 and three loci. This is particularly true for...

Size and shape

Size and shape are attributes of major significance for Brassica crops. Size requirements for fresh vegetables have diminished sharply in parallel with the reduction in the size of family units and rising dominance of single persons catering for themselves. Consumers demand produce that is easily and quickly prepared and can be consumed at one sitting. Few retail purchasers require products larger than 0.5 kg and frequently even smaller portions are demanded. Consequently, growers are required...

Size of head

Head size is a quantitative trait and may be related to hybrid vigour, but not necessarily as open pollinated lines can be just as large. Cabbage is responsive to day length, and in northern latitudes such as Alaska the cabbages can become very large, weighing as much as 20 kg. Likewise, the further south or the shorter the day length, as in winter, the smaller the head. Agronomic issues such as crop spacing and row spacing confound head size. Dense cropping naturally results in smaller heads.

Developmental Physiology

Physiology describes and measures the genetically driven processes of growth and reproduction, and relates these to environmental factors such as temperature, radiation, photoperiod and nutrient availability. It strives to understand the interaction between genotype and environment. Crop physiology has immediate practical significance by permitting the prediction of growth and maturity rates as affected by changing patterns of weather and other events. Managing Brassica crops is notoriously...

Pathogens

Postharvest damage from diseases usually results from infections that happen either in the field or as a result of damage during harvesting and storage followed by the invasion of pathogenic microbes. Control of many storage rots was achieved with fungicidal dips applied postharvest, but this practice is becoming less acceptable since there is little opportunity with stored produce for the active ingredients to be dissipated by active metabolism. The ubiquitous grey mould fungus, B. cinerea, is...

Nutrition

The original wild progenitors of cultivated brassicas were capable of surviving in inhospitable arid conditions with minimal availability of nutrients see Chapter 1 . In stark contrast, cultivated brassicas are very responsive to increasing supplies of nutrients, particularly nitrogen and water. Traditionally, they have been used as the leading crop in rotations planted following the application of organic or animal manure, emphasizing their responsiveness to nitrogen fertilization in...

Examples Of Crop Responses To Nutrients

Brussels sprout crops require up to 300 kg of nitrogen ha for optimal yield. Total aerial biomass production and nitrogen uptake rates increase strongly with nitrogen applications, mainly because of its pronounced effect on leaf area expansion Booij et al., 1996 . A high nitrogen uptake rate rapidly depletes nitrate reserves in the soil Booij et al., 1993 . Crop growth of Brussels sprouts has two phases see Chapter 4 Abuzeid and Wilcocksen, 1989 . In the first phase, biomass increase is mainly...

Genomic Characters And Taxonomy

The following six Brassica species, plus Raphanus sativus, radish 2n 18, have been inter-crossed, with varying levels of difficulty requiring embryo culture or fusion to obtain hybrids Brassica nigra Koch, black mustard, 2n 16 Brassica carinata Braun, Ethiopian mustard, 2n 34 Brassica juncea L. Coss, brown mustard, 2n 36 Brassica napus, swede or rutabaga, rape or oilseed rape canola 2n 38 Brassica rapa, turnip and Chinese cabbage, 2n 20 and Brassica oleracea, cole crops, 2n 18. Table 2.1 shows...

Seed Purity

Control of seed purity is vital for all crops, but is of particular importance with vegetable brassicas where the uniformity of the plant stand is essential for the future profitability of the crop. The detection and elimination of siblings is of particular importance where F1 hybrids are predominantly used as cultivars as with most Brassica crops. The sibling problem arises because B. oleracea possesses a single locus, multiallelic, sporophytic incompatibility system. Plant breeders usually...

Albugo Candida white blister or white rust

Control can be achieved by preventative and eradicant fungicidal sprays against foliar and systemic infections. Race-specific resistance governed by single dominant genes has been identified in several Brassica and Raphanus spp. quantitative inheritance of disease reaction type was demonstrated in B. rapa. Resistance to race 2 of A. candida is controlled by a single dominant gene, and resistance was associated with leaf pubescence, which is also governed by a single dominant allele Kole et al.,...

Effective Cultural Practices

Cultural weed control aims to optimize sowing or planting dates, seed rates or transplant densities, spacing layouts, soil fertility, irrigation practices and cultivar selection to achieve rapidity of crop growth which is able to outcompete weeds for resources. The aim should be to ensure either that the crop plants emerge first or that transplants can establish ahead of weed development and close their canopy over the weeds, thereby smothering them. Manipulating crop geometry can radically...

Senescence

Senescence applies to the physiological changes in flavour, composition and structure initiated by the cessation of growth at harvesting. The term deterioration includes senescence and the effects of pests, pathogens, disorders and mechanical damage before and after harvest. Deterioration in the Brassica crops can take on many forms, but is most widely characterized by chlorosis or yellowing resulting from a breakdown of chlorophyll pigments within the tissues. Taken to the ultimate stage, the...

Rotation

The manipulation of husbandry systems to lessen the impact of pests and pathogens is the major avenue for the control that is directly placed in the hands of the grower. Such an approach is particularly appropriate with soil-inhabiting organisms. One of the first elements of husbandry control is the Table 7.2. Comparison of black rot disease severity ratings Xanthomonas campestris pv. campestris following the inoculation of seedling and mature plants. Table 7.2. Comparison of black rot disease...

Winter cultivars

The best cultivars for growth in more southern regions in the winter, and which may be subject to considerable cold, should be bolting resistant, and require a long cold induction before flower stems will develop. They are often slightly savoyed. Selection can best be done in areas where they will be grown and subject to cold induction. They should be planted earlier than for the commercial crop so that they are larger when the cold develops and are subject to longer periods of cold. Plants...

Physical barriers

Crop covering involves laying transparent plastic sheets over drilled or transplanted crops. The growing plants support the cover as they develop underneath. Alternatively, opaque plastic sheets are placed on the soil surface and on the crop. Then the crop either grows through holes in the sheet or is transplanted through them. Both covers and mulches offer barriers between the developing crop and pests. For Brassica crops, covers have more universal value in the control of pests. The original...

Natural products

As an alternative to conventional synthetic pesticides, recently interest has focused on evaluating plant extracts as potential insecticides on the premise that these materials are less specific in their mode of action. Hence insects will require longer lasting resistance in order to circumvent them. In addition, plant extracts are mostly biodegradable, which suggests that their application would be more environmentally acceptable and compatible with IPM programmes. Numerous plant extracts or...

Seed Priming

Seeds require water, oxygen and a suitable temperature for germination. Water uptake follows a three-phase pattern with an initial rapid uptake or imbibition phase 1 , followed by a lag period phase 2 and then a second increase in water uptake associated with seedling growth phase 3 . Seeds are tolerant of desiccation during phases 1 and 2 but frequently intolerant of it in phase 3 Taylor et al., 1998 . Water uptake may be either uncontrolled or controlled. In the former, water is freely...

Chinese cabbage

The storage life of Chinese cabbage is relatively short, extending to only a few weeks at 0-1 C yellowing caused by tissue senescence is a major source of spoilage even under these conditions. Leaf spotting Alternaria spp. will develop in stores at 0-1 C and 95-97 relative humidity, and may be accelerated at higher temperatures. Soft rotting E. carotovora is a major source of postharvest damage during the transit and storage, and blackening of the leaf veins is caused by Xanthomonas campestris.

Tipburn

Internal tipburn is one of the most common physiological disorders affecting a wide range of vegetables and fruit. A necrotic breakdown of the marginal tissues of leaves is seen in cabbage heads both Chinese and European cabbage are afflicted. Tipburn is usually attributed to localized calcium deficiency and related in incidence to genotype and prevailing weather conditions, and the availability of nitrogen fertilizer. Large applications of easily available nitrogen at transplanting increase...

Heat tolerance

Brocoli Bracting

Cauliflower is heat susceptible, but not to the same extreme degree as broccoli. Some of the Indian cauliflowers such as 'Pusa Katki' have the greatest heat tolerance, but these are early and have relatively poor quality curds. If the temperature is high, then the curd may develop bracts green bracts corresponding to auxilary leaves are usually present in the curd, Fig. 2.6 which make it unmarketable. Bracting is recessive, and heritability was reported at 73 . The curd may also produce true...

Brussels Sprout B Oleracea Var Gemmifera

The imperative for improved understanding of growth and maturity in Brassica crops began with Brussels sprouts in the early 1960s as their production for quick-freeze processing took an increasing share of the market especially in the early and mid-season periods. The processing companies demanded regular and predicable supplies entering their factories so that the production lines operated at maximum efficiency as had previously been achieved for vining peas and green beans. Plant breeders...

Seed Size And Maturity

In Brassica spp., determination of seed maturity is complicated by the indeterminate growth and extended flowering periods of the parent plants Jett and Welbaum, 1996 . Overall inflorescence development continues for a considerable period of time within individual racemes and between different racemes. The processes of flower opening, pollination and fertilization each requires an extended period of time, causing the fruits and seeds to mature in rotation. Harvesting too early results in poor...

Seed Coating

Seeds vary greatly in size, shape and colour. Many seeds are small and irregular, making their separation and precision placement in the field difficult. Additionally, seeds require protection from pests and pathogens. Seed coating is used to allow mechanical sowing in precise patterns. This achieves uniformity of plant spacing and provides carriers for plant protection agents. Seeds may be both pelleted and film coated. Pelleting is defined as the deposition of a layer of inert material that...

Transferring High Quality From Field To Plate Shelf life

Development, pre-maturation, maturation, ripening and senescence are the five phases that vegetables and fruit pass through during production, harvesting, storage and into the distribution chain to the ultimate retail consumer. Brassica crops are not required either to ripen or to senesce. These phases are mainly reserved for fruit crops. Indeed, senescent Brassica crops are generally unmarketable and worthless. Development in terms of product quality begins with the initiation and subsequent...

Temperature

Crop temperature is not normally controlled in open field crops. The advent of plastic film covers and mulching, however, permits some modest manipulation of temperature. Mulching in spring increases soil and air temperature. This advances the date of transplanting and accelerates growth, leading to earlier maturity. The timing of mulch removal becomes critical in late spring or early summer to sustain the quality in crops such as broccoli, leafy and hearted cabbage and some forms of early...

What Are Weeds

An ecologist defines weeds as 'plants growing entirely or predominantly in situations that are disturbed by man without being deliberately cultivated' G.R. Dixon 2007. Vegetable Brassicas and Related Crucifers G.R. Dixon Baker, 1965 . This definition includes all plant types, not solely the flower-forming angiosperms, although these comprise the great majority of weed taxa. The world weed flora mainly contains plants from relatively few, highly advanced families Table 6.1 Hill, 1977 which...

Floral Biology As Related To Controlled Pollination

Controlled Pollination

The flower Fig. 2.1 differentiates by the successive development of four sepals, six stamens, two carpels and four petals. The carpels form a superior ovary with a 'false' septum and two rows of campylotropous ovules. The nucellar tissue is largely displaced by the embryo sac and, when the buds open, the ovules mainly consist of the two integuments and the ripe embryo sac. The buds open under pressure from the rapidly growing petals. Opening starts in the afternoon, and usually the flowers...

Internal browning

Internal browning of Brussels sprout buds was seen mainly as a problem for quick-freeze crops where even a small percentage of blemished buds would cause rejection since affected buds could not be identified and extracted from Table 8.4. Nutrient composition of field-grown cauliflower leaves showing normal and tipburn growth. Nutrient composition percent dry weight Table 8.4. Nutrient composition of field-grown cauliflower leaves showing normal and tipburn growth. Nutrient composition percent...

Wild hybrids

Wild Brassica and its close relatives hybridized naturally, forming polyploids. These amphidiploids together with their parental wild diploids were key building blocks from which our domesticated brassica crops have evolved. Three hybrid species are of particular interest as ancestors of the crop brassicas. Brassica carinata n 17 was formed from B. oleracea n 9 X B. nigra n 8 . This species is characterized by the slow steady growth of B. oleracea and the mustard oil content of B. nigra. Wild...

Trace Elements

Depending on soil type, soil pH and crop sensitivity, trace element deficiencies can develop and cause significant crop losses. Deficiencies of trace elements have substantial effects on the yield, quality and storability of Brassica crops. Cauliflower and swede are susceptible to boron deficiency, especially when grown on light soils with pH values gt 6.5. Boronated fertilizers should be used as a matter of routine, or applications made to the seedbed or prior to transplanting at 20 kg ha...

Defects

Crop defects may have genetic, physiological, pathological or mechanical origins, or alternatively result from the presence of extraneous organic or inorganic items. Defects inherent in the crop resulting from interactions between genotype, environment and microbial pathogens are dealt with later in this chapter. Surface blemishes, insect deposits, fungal growth, necrotic zones and virus-induced yellowing can all constitute defects of Brassica crops. Mechanical damage includes cuts, bruises and...

Field monitoring

Disease Assesment Keys

Regular crop walking and inspection are essential for the successful prediction of pest and pathogen epidemic development. The crop is inspected at regular intervals to determine whether pest and pathogen problems are emerging. Quantitative evaluations of a developing pest or pathogen problem are gained visually through the manual use of pests and disease assessment keys that quantify developing signs and symptoms. Examples are shown in Figs 7.2 and 7.3 for powdery mildew E. cruciferarum on the...

Seed Increases

Hand pollination is best performed in the greenhouse or in a large screened cage to eliminate insects. If cross- or self-pollination is desired in the field, cheesecloth bags can be used to enclose the blossoms of one or two plants. It is preferable to enclose several plants in a screen cage 2 m high. The plants should be held away from the cage walls to avoid pollination through them by visiting bees and other insects. Bees are the best pollinators, but flies can also be used. If large-scale...

Weed Control In Brassica Seed Crops

Brassica seed crops suffer from weed competition in an analogous manner to ware or cash crops. Weed competition may reduce seed yield dramatically in cabbage by gt 50 Al-Khatib and Libbey, 1992 Al-Khatib et al., 1995 . The presence of weeds at seed harvest increases mechanical damage to cabbage seed and reduces harvest efficiency weeds also reduce seed quality by interfering with the processing operations. Weeds such as bedstraw or cleavers Galium aparine , charlock 5. arvensis and wild mustard...

Mamestra brassicae cabbage moth

Several wasps colonize the eggs Trichogramma evanescens , larvae Apanteles glomeratus and Hyposoter ebenius and pupae Ptetomalus puparum and Pimpla instigator additionally the flies Phryxe vulgaris and Compsilura concinnata are parasites of M. brassicae. Studies indicate that species of fungal and viral parasites offer potential biological control systems the larvae are not susceptible to current commercial strains of B. thuringiensis unlike other lepidopteran pests e.g. Pieris spp. ....

Cabbage head shape

The desirable cabbage head shape in commerce has changed from pointed, flat or round to almost exclusively round. Pointed head is dominant to round. Many genetic factors, however, influence head shape. Selection is best made by cutting the head vertically through the core this allows selection for head shape, core length, diameter and solidity, or leaf toughness, leaf configuration within the head and leaf or rib size. The cut core will heal and lateral buds develop from it so that selected...

Crop Monitoring Forecasting And Disease Management

The philosophy of 'forewarned is forearmed' whereby pest and pathogen invasion is anticipated and crops monitored for the first signs of their arrival is not new, but the application of new technologies makes it more efficient and effective. Monitoring Brassica crops helps to ensure that control measures, particularly where chemical methods remain available, are applied swiftly and effectively, and as part of the integrated strategy. This contrasts with the previous practices whereby chemical...

Breeding Procedures Male sterility

Male Sterile Seed

A considerable number of dominant male sterility genes have been found. Some have been used to a limited extent employing asexual propagation to multiply the sterile lines for hybrid seed production. The prime future method for hybrid production, however, is likely to be via cytoplasmic male sterility This is rapidly moving to the forefront of methods for production of new hybrids in the vegetable brassicas. Older established hybrids will continue to use self-incompatibility. The first B....

Overwintered cauliflower Roscoff and Walcheren types

The overwintered crop is transplanted into the field in mid to late summer, forming a large framework of leaves in the juvenile phase. Only very limited and, in some cases, rudimentary information is available concerning curd initiation by winter cauliflower. Information available for these crops in general compares poorly with summer and autumn types where recent research has made significant advances in defining the parameters controlling plant juvenility and maturation, and the subsequent...

Health And Welfare Benefits

The hidden attributes of Brassica crops lie in their abilities to reduce the incidence of human cancer and coronary diseases when consumed over periods of years as part of a balanced diet. Medical evidence for these attributes has accumulated substantially in the past decade, and these properties are coming into prominence with the general public Mazza, 2004 see Table 8.1 . In this respect, the Brassica crops, such as broccoli calabrese , have especial interest because of their sulphorathane...

Examples Of Germination And Vigour Tests Standard germination tests

These are performed according to internationally accepted rules established by the International Seed Testing Association ISTA using prescribed temperature regimes. Example regimes could be either continuous 20 C or alternating 20 30 C during dark and illuminated periods. Lighting regimes are also standardized. Radicle emergence is recorded daily for the first 5 days of incubation, and counts of normal and abnormal seedlings are made after 10 days by suitably qualified seed analysts.

Broccoli Breeding Heat tolerance

Italica Group Broccoli

Susceptibility to high temperature damage is one of the major problems in broccoli. This makes the crop agronomically more suitable for cultivation in cool, moist climates. Heat at harvest time is not critical, except for the fact that high temperatures will reduce the period over which the crop is marketable. About 3-4 weeks prior to the head being marketable is the critical period when the growing point is differentiating to become reproductive Chapter 4 . Bjorkman and Pearson 199 7 studied...

Callus Culture Fusion And Transformation

Tissue culture techniques have been applied to several B. oleracea vegetables, either for clonal propagation or for development of novel and sometimes improved plant types. Plants have been regenerated from diverse multicellular explants, including immature embryos seedling parts such as hypocotyls or cotyledons stem pieces leaves roots and floral tissues such as flowering stalks or caulilfower curds. Plants can be recovered from single wall-free protoplasts, usually isolated from leaves or...

Cauliflower B Oleracea Var Botrytis Summer early and late and autumn maturing genotypes

Buttoning Cauliflower Curd Crop

The cauliflower is a short caulescent plant with shoot tips composed of young leaves and leaf primordia situated around an apical dome and separated by expanding internodes. In comparison with most Brassicas, the shoot tip components of the cauliflower are large, and easy to detach, measure and analyse following environmental changes. The grower's cauliflower consists of a large immature inflorescence the curd , formed at the stem tip after a period of vegetative growth. The growth phases of...

Bud pollination

Bud pollination to overcome self-incompatibility is accomplished by opening the bud and transferring pollen from an open flower of the same plant. Fertilization will not occur where this is done when the bud is very small. At this stage, the style is not receptive, but about 3-4 days before the flower has opened the style and stigma are fully receptive and the self-incompatibility factor has not yet developed, therefore self-fertilization is possible and self-incompatibility can be bypassed....

Brassica rapa group n the Oriental group

Brassica Campestris Var Cephalata

The International Code of Botanical Nomenclature Gilmour et al., 1969 Greuter et al., 2000 rules that the author who first combines taxa of similar rank bearing epithets of the same date chooses one of them for the combined taxon. Metzger 1833 first united B. rapa L. and B. campestris L. of 1753 under B. rapa L. as used in this text. Brassica rapa L. n 10, A and the amphiodiploids B. carinata Braun n 17, BC , B. juncea Coss n 18, AB , B. napus L. n 19, AC and R. sativus n 9, R are grown...

Seedling Propagation

The plant breeding and seed industry has refined Brassica seed into a defined and reliable resource. This makes it a major item of cost in the crop balance sheet. As a result, its initial propagation into seedlings has also become refined and diverged as the separate and specialized industry of plant propagation. Frequently this is quite distinct from the production industry that produces the finished item that is sold to retail consumers. The separation of propagation and production enables...

Soil Ph And Calcium Content

Brassica crops are most productive when grown on land with an approximately neutral pH. The ideal is pH 6.5 for mineral soils and pH 5.8 for organic soils. This rule should be altered where soil-borne pathogens are present, especially Plasmodiophora brassicae, the causal agent of clubroot disease. Land where even very low levels of infection are present should be raised to pH values in excess of 7.0. Brassica crops vary in their sensitivity to acidic pH and the point at which crop productivity...

Crop density

Stand density and crop plant architecture will affect the risk of disease infection and its subsequent impact. Stand density affects air movement, shading and moisture retention within the crop. Root 1973 proposed the 'resource concentration hypothesis' whereby 'any herbivores, especially those with a narrow host range are more likely to find hosts that are concentrated'. This hypothesis predicts that the density of herbivores per host plant is higher in dense stands of their host plants. The...

Contrasting the physiology and morphology of wild and cultivated brassicas

Wheat Genome Evolution

It will be evident by now that many of the wild Brassica spp. and their close allies inhabit dry coastal, arid rocky or desert habitats. These wild plants have very thick leaves containing less chlorophyll and many more cell wall components compared with cultivated plants. Typically, they have well-developed xylem vessels and small leaf areas these characteristics increase the efficiency of water conservation in plants. The foliage of wild xerophyllous the group including Brassica and other...

Physiological Disorders

Storage losses of Brassica vegetables such as winter white cabbage and Chinese cabbage are regularly reported at 10 and frequently exceed this figure. The Brassica crops suffer from a range of physiological disorders that are major causes of these losses after harvesting. Physiological disorders have been attributed to a range of nutrient deficiencies interacting with environmental or climatic conditions and, more recently, the effects of virus pathogens. It appears that under specific...

Fertilizer Applications

General fertilizer requirements for a range of Brassica vegetables are given in Table 5.6. These bear out the more specific requirements cited in the other tables indicating that these crops benefit from substantial applications of major nutrients. To avoid damage to the root systems by increasing soil conductivity to dangerous concentrations, it is advisable to apply nitrogen in particular as split dressings, with half applied to the seedbed or at transplanting and the residue about 2 weeks...

Cigar burn

Cigar burn is one of the major internal disorders of cabbage B. oleracea var. capitata . It is seen as sunken necrotic spots 5-10 mm diameter on internal tissues. Walsh et al. 2004 added evidence that virus pathogens may also be implicated in these syndromes Table 8.6 . They proposed that cigar burn is caused by turnip mosiac virus TuMV on cvs Polinius and Impala. The condition reached its most severe level at 4 months in store and did not progress after that date. The presence of cauliflower...

Advantages Of Arabidopsis Thaliana

The main objective is to clone genes that have been identified by mutational analysis. The combined efforts of many laboratories have resulted in a completed outline map of the A. thaliana genome. Detailed maps of morphological and biochemical markers such as RFLPs and RAPDs are available for much of the genome. Approximately 90 of the total A. thaliana genome lies within 0.8 Mbp of an RFLP marker and 50 is within 0.27 Mbp of an RAPD marker. The genome of A. thaliana lacks much of the...

Sclerotinia sclerotiorum white rot white mold in the USA

Control of this pathogen is extremely difficult because of its wide host range and formation of persistent sclerotial resting bodies. Resistance is recessive and quantitative. The introduction line PI206942, a non-heading cabbage from Turkey, has shown superior levels of resistance Dickson and Petzoldt, 1996 . Resistance was transferred to cabbage, broccoli and cauliflower. Sharma et al. 1995 reported that cauliflower cv. Early Winter Adam's White Head and EC 162587 were highly resistant, and...

Rapid Cycling Brassica Types

Rapidly reproducing forms of Brassica named 'Fast PlantsTM' have been bred for use in association with inexpensive growing systems developed from recycled plastic containers. This combination offers an effective and efficient set of tools for biological studies at all levels of complexity from the research bench to school students. Depending on the genotype used, Fast PlantsTM will germinate in 1 day, grow and flower in 2 weeks and produce viable seed in little more than 28 days. Changes in the...

Diversity within the amphidiploids

Examples Amphidiploid

Considerable genetic diversity is present within the three amphidiploid species Song et al., 1996 . Based upon studies of genetic diversity, B. napus may be considered as the most ancient amphidiploid, succeeded by B. juncea and B. carinata. Two major factors are responsible for general diversity within amphidiploids multiple hybridizations with different diploid parents and genome modifications following polyploidization. A good example of multiple hybridizations was found in B. napus. Four...

Effects Of Weed Type

Model Yield Loss Weed Density Cousens

The morphological habit of a weed will substantially affect its impact on the growth and yield of the crop. For tall-growing weeds such as C. album fat hen , there is a linear relationship between the extent of yield reduction and weed Fig. 6.1. The rectangular hyperbolic model for relating yield loss to weed density, illustrating its parameters A and I. YL percentage of yield lost because of weed competition d weed density I percentage of yield loss per unit weed density as d 0 A percentage of...

Strategies For Pest And Pathogen Control Host resistance

Aleyrodes Proletella Life Cycle

Genetic resistance to pests and pathogens is the principal means of control that is both economically and environmentally acceptable. Plant resistance to insects can result from i antixenosis or the dislike of the plant or non-preference Kogan and Ortman, 19 78 ii antibiosis or antagonistic reaction resulting from the presence of harmful compounds or iii tolerance and combinations of these attributes. Fig. 7.4. Food consumption by cabbage white butterfly Pieris rapae larvae of the fourth instar...

Meligethes spp blossom beetles

Meligethes Spp

The biology of beetles is discussed by Booth et al. 1990 . Trap crops may be employed to divert these pests from summer cauliflower success has been achieved at control using this technique with flowering crops of Chinese cabbage, broccoli calabrese , sunflower, marigold and oilseed rape. The disadvantage of this method is that a substantial area of land is diverted from the cash crop to the trap crop. Spray applications may be based on the population density of adult beetles and for autumn...

Nontillage And Tillage Cultivation Systems

Non-tillage systems are a means of managing the disposal of crop residues with minimum cultivation Unger and McCalla, 1980 . Synonyms for this approach include conservation tillage, direct drilling, eco-fallowing, limited tillage, minimum tillage, no-tillage, reduced tillage and stubble mulching. The process resembles the use of organic mulches. The aims are leaving sufficient plant residues on the soil surface at all times to reduce wind and water erosion The impact of this form of husbandry...

Manipulating Drilling Or Planting Dates And Crop Geometry

Increasing plant population densities is a useful technique for raising yield and potential profits in brassicas. For high-density cole crop production to be successful, however, nitrogen applications should increase to accommodate increased nutrient demands. The use of high-density populations has certain disadvantages. Broccoli and cauliflower yields per unit area normally increase with closer planting densities but are associated with smaller head size. While this may increase the numbers of...

Growth stages

Sprout Apical Growth

The growth stages of Brussels sprout are as follows Juvenile 1. The stem apex is flat and very small perhaps four rudimentary leaves and three primordia present. Fig. 4.1. Illustration of the developmental stages of the apex of Brussels sprouts Brassica oleracea var. gemmifera Stokes and Verkerk . Fig. 4.1. Illustration of the developmental stages of the apex of Brussels sprouts Brassica oleracea var. gemmifera Stokes and Verkerk . Fig. 4.2. Illustration of the changes in the structure of the...

Aleyrodes proletella L cabbage whitefly

Once established in a crop, whitefly are amongst the most difficult pests to eradicate. This pest inhabits the undersurface of leaves consequently control is only effective when insecticides are directed at high volume on to this target with suitable drop leg spray booms Mound and Halsey, 19 78 Bryne and Bellows, 1991 . Control is essential in vegetable brassicas to achieve clean, high-quality produce acceptable to supermarkets. Pyrethroid formulations will kill all stages, whereas others are...

Controlled deterioration test

The moisture content of seed is adjusted to 24 and they are sealed in laminated polyethylene-aluminium foil pouches and held at 1 C overnight allowing moisture to equilibrate throughout the seed sample. The sealed pouches are then placed in a water bath at 45 C for 24 h Matthews and Powell, 1987 . The standard germination test is then made at 20 C and normal seedlings counted. The measurement of chlorophyll content of seed has been suggested as a means of determining seed maturity and quality...

Brassica Juncea L Czernjaew

Sinapis juncea L. 1753 , S. timoriana DC 1821 , B. integrifolia West Rupr. 1860 . Brassica juncea crops are grown worldwide, from India to northern Africa, to central Asia the southern and southeastern part of the former Soviet Union , to Europe and North America. The exact origin is unknown, but as an amphidiploid it seems logical that it originated in an area where the parental species B. nigra L. Koch and B. rapa L. overlap in their distribution e.g. central Asia . It is generally...

Pepper spotting

Pepper spotting develops inside cabbage heads, especially the Dutch or white cabbage that are stored for several months Cox, 1977 . Pepper-spot is seen as clusters of small black spots lt 1 mm diameter. The causes of pepper spotting synonymous with pepper-spot, grey speck and black speck are unknown. The use of controlled atmosphere storage 2.5-3.0 oxygen and 5.0-6.0 carbon dioxide will extend cabbage storage life for 5-6 months at 0 C, delay yellowing and maintain good quality characteristics....

Packaging

Packaging is a standard requirement for Brassica crops in transit to the retail consumer. Effective packaging will enhance the attractiveness of the product and retain quality characters for longer periods. Defective packaging accelerates deterioration and destroys quality. Deterioration is especially rapid where packaging allows the accumulation of toxic compounds, such as ethylene, that contribute towards accelerated deterioration. The formation of ethylene speeds up the processes of...

Intercropping

Increasing crop specialization and intensification in developed countries have virtually eliminated the use of rotations for vegetable Brassica production, resulting in undesirable side effects such as soil compaction, loss of soil structure and decreased organic matter content Nicholson and Wien, 1983 . Research indicates that intercropping with rows of plants whose purpose is soil improvement, placed between the economic crop, restores soil structure with minimal deleterious effects on the...

Weed Management

Integrated crop management ICM identifies the weed problems through regular crop inspections so-called 'crop walking' see also Chapter 7 . In turn, this is combined with preventative, cultural, mechanical, biological and chemical control methods in a compatible manner to solve the problem. Integrated methods avoid relying solely on one management tool and help reduce the need for chemical weed control by combining a series of approaches to profitability, producing a marketable product while...

Alternaria spp dark leaf and pod spot

Alternaria Brassicae

Host resistance is dominant and quantitative to this pathogen. Selections from species such as B. tournifortii, Camelina sativa, S. alba, Capsella bursa-pastoris and B. carinata appear to be highly resistant. Successful fusion of C. sativa with B. oleracea transferred a high level of resistance to B. oleracea Sigareva and Earle, 1995 . Subsequently, Hansen and Earle 1997 fused S. alba with B. Fig. 7.14. White blister or white rust symptoms Albugo candida . Fig. 7.14. White blister or white rust...

Brevicoryne brassicae L cabbage aphid and Myzus persicae Sulzer green peach aphid peachpotato aphid

Diagram Green Peach Aphid

The intensity of aphid epidemics is regulated by the prevailing weather. In warm dry conditions, there is rapid and extensive colony growth, while cool damp weather inhibits population expansion Blackman and Eastop, 1984 Minks and Harrewijn, 1987 . Initial spring invasions rely on the proximity of overwintered crops to new plantations consequently field hygiene by ploughing in or rotavating residues is of paramount significance to deprive these pests of sources of cover for hibernation....

Micropropagation

The Numbers Structure Cabbage

Microspore-derived embryogenesis was first completed successfully on broccoli by Keller et al. 1975 from isolated anthers. Now embryogenesis of microspores is quite routine in most large-scale crucifer breeding programmes. There are still differences between sources of microspores which affect the number of embryos that are regenerated per anther, but the system is now well developed, and gt 1000 per bud can be produced. The size of the Fig. 2.2. Generalized structure of the dry fruit of...

What Is Quality

Quality is a subjective and somewhat nebulous attribute composed of components that vary with different Brassica crops and the attitudes of individual consumers. Basically these components may be grouped under four general headings sight colour, gloss, viscosity, size and shape, and obvious defects touch or texture in hand, finger and mouth smell and taste or flavour hidden factors such as nutritional value, and the presence of either harmless adulterants or toxic elements.

Starter fertilizer

An alternative is to use small volumes of liquid 'starter' fertilizer applied close to the transplant as it enters the planting station, making it readily available to the roots emerging from the propagation module. Several studies have demonstrated that this technique increases the rate of the early growth phases of crops and is ultimately expressed in additional yield. Such benefits have been achieved even where the soil has a high residual nutrient status or where ample fertilizer has been...

Agrotis spp especially the turnip moth Agrotis segetum cutworms

Agrotis Spp

This pest is of greater significance in seed compared with ware crops. A spatial barrier of 500 m between new and old season seed crops is frequently sufficient to prevent infestation because the adults are weak fliers. Brassica crops vary in their attractiveness to this pest, with fewer eggs being laid in mustard crops such as B. nigra black mustard , B. juncea leaf mustard and B. carinata Abyssinian mustard compared with forms of B. rapa and B. napus. Forecasting using computerized prediction...

The Crucifer Genetics Cooperative International Collaboration And Brassica Symposia

The development of rapid-cycling Brassica genotypes prompted the formation in 1982 of the Crucifer Genetics Cooperative CrGC in the USA, as a vehicle for distributing seed and information amongst research workers and others around the world. Since 1982, CrGC has held regular meetings to discuss research findings. In 1994, the 9th CrGC workshop was held in Lisbon, Portugal in collaboration with the 1st International Brassica Symposium sponsored by the International Society for Horticultural...

Fusarium oxysporum fsp conglutinans cabbage yellows

Control of F. oxysporum f.sp. conglutinans is largely achieved by the use of resistant cultivars and is a classic example of the success of this approach, which has remained effective for decades in the USA. Although the pathogen is extremely variable in its growth characteristics in vitro, it is stable in pathogenicity towards its hosts. Initially, field selection for resistance within diseased crops resulted in the release of cv. Wisconsin Hollander. Subsequently, this cultivar was found to...

Raphanus Sativus L Radish

Four cultivar groups of culinary radish are recognized Chinese radish daikon , leaf radish, rat-tailed radish and small European types. The origins of culinary radish are not known since there is no immediately obvious wild progenitor. The zone of maximum diversity runs from the eastern Mediterranean to the Caspian Sea and eastwards to China and Japan. Radish crops were cultivated around the Mediterranean before 2000 BC and are reported in China in 500 bc and Japan in 700 ad. They are now found...

Brown bead

Brown bead was first seen in broccoli B. oleracea var. italica in California in the 1970s as a physiological disorder and caused the abandonment of substantial areas of crop because of lost quality. This disorder was also found in Canada Jenni et al., 2001 . The evidence used to explain its incidence is confused and inconclusive. There is no correlation with nitrogen fertilization, but low calcium content associated with rapid growth has been related to the incidence of brown bead there is also...

Plasmodiophora brassicae clubroot

Sistance Plasmodiophora Brassicae

Most resting spores of P. brassicae in field soils are concentrated in the upper profiles, decreasing gradually with depth, soil type, tillage practice and cropping history. Spore dissemination is via drainage water, organic material derived from infested roots, wind-borne soil particles and diseased transplanting material. Contaminated transplants are a major means for the long-range spread. Recently, P. brassicae has been identified in peat used in composts for container-grown Brassica...

Seed Vigour

Seed vigour may be defined as 'the sum total of the properties of seed which determine its potential activity and performance during germination and seedling emergence' adapted from Perry, 1978 . Seeds are subjected to varying degrees of water and temperature stress during their development, maturation, harvest and storage during seed production, and then again during rehydration and germination following sowing. Those with high vigour are capable of rapid germination and the establishment of...

Postharvest treatment

The edible portions of the crop while attached to the growing plant derive their constituents of quality in relation to its rates of nutrient uptake, photosynthesis, respiration, transpiration and other metabolic processes. Once harvested, each portion becomes an independent entity where quality is controlled by its innate rates of respiration and transpiration. Excessive transpiration is the greatest source of postharvest damage to quality. All Brassica crops need to be maintained in a turgid...

Erysiphe cruciferarum powdery mildew

Erysiphe Cruciferarum Control

Considerable efforts are being made to control E. cruciferarum using resistant cultivars. Resistance in cabbage is attributed to a single dominant gene that is Fig. 7.15. Powdery mildew Erysiphe cruciferarum symptoms on Brussels sprout leaf. Fig. 7.15. Powdery mildew Erysiphe cruciferarum symptoms on Brussels sprout leaf. influenced by numbers of minor genes, since in parental generations resistance is incompletely dominant. Thus, under conditions of heavy inoculum, a heterozygotic host may...

Chemical Management Of Weeds

Chemical management of weeds includes the use of herbicides and soil fumigants. In the past, fumigants have been used on land where intensive brassicas are grown. In particular, this involved the use of methyl-bromide to destroy soil-borne pathogens and weed seeds. Use of this chemical is being discontinued internationally to prevent further damage to the atmospheric ozone layer, and safer alternatives are being sought. Herbicides may be selective or non-selective in their mode of action....

Cold and heat damage

Brassica vegetables are evolutionarily suited to cool to warm temperate conditions. Some of the head cabbage, Brussels sprout and kale types can withstand low and freezing temperatures. Opportunities to improve frost tolerance in cauliflower have not been exploited sufficiently despite some strains being regularly used over winter Deane et al., 1996 . Breeders have Table 8.6. Viruses associated with physiological disorders in brassicas. Table 8.6. Viruses associated with physiological disorders...

Effects Of Tillage Implements

Ryegrass Failure

Vertical gradients in the soil microclimate such as water availability, temperature and light occur in the field Heydecker, 1973 Fenner, 1985 , so that one of the major factors influencing the success of weed germination and emergence is the position of a weed seed within the soil profile. Chancellor 1982 identified that weed seeds have mechanisms that respond to these gradients, thereby preventing germination at depths from which the seedling cannot reach the soil surface. Mechanisms such as...

Cauliflower and broccoli calabrese curd or spear maturity

Predicting when a broccoli calabrese or cauliflower crop will mature is vital to modern marketing practice because it determines when supplies of the product will be available and enables the grower or cooperative to adjust marketing strategy in anticipation of crop maturity. The maturity of a broccoli calabrese head spear is primarily determined by developmental states of the florets. The head is harvested shortly before the flowers open. Since flowering as in most species follows the...

Cauliflower

Cauliflower is normally only stored for short periods to fill gaps in the supply chain caused by periods of hot dry weather. There also appears to be interest in storing cauliflower florets for longer periods following blanching and dehydration for subsequent use in catering packs Kadam et al., 2005 . Under optimal conditions 0 C and 95 relative humidity , cauliflower may be stored for up to 6 weeks. In practice, storage beyond 2-3 weeks is inadvisable. Cauliflower curd is very susceptible to...