Floral Biology As Related To 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
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
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
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
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
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
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
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
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
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 Fig
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
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
Syn. 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
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
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
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 Fig
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...