Crop research may be defined as activity directed to making the production, marketing and use of commercial CROPS more efficient and profitable.
Crop research may be defined as activity directed to making the production, marketing and use of commercial CROPS more efficient and profitable. Hence, crop research may comprise any or all of the following: PLANT BREEDING, plant physiology and BIOCHEMISTRY, crop protection, cultural management, storage methods research and processing and products studies. The importance of plant breeding in the adaptation of crop plants to Canadian conditions is treated in a separate article. Well-known successes include MARQUIS WHEAT, TRITICALE, CANOLA and LENTILS. Crops include grain and OILSEED CROPS, FORAGES, speciality crops, VEGETABLES, FRUITS and ORNAMENTALS.
Plant Physiology and Biochemistry
Canadian plant physiologists and biochemists have contributed to both on-farm research and basic research conducted under carefully controlled conditions at the laboratories of the NATIONAL RESEARCH COUNCIL, Agriculture and Agri-Food Canada (AAFC) AGRICULTURAL RESEARCH STATIONS and the universities. Important work has been done in tissue culture, weed control, host-parasite relationships and PESTICIDE research.
Although weed competition, insects, fungi and bacteria were serious problems from the beginning of agricultural practice in Canada, weed-control chemicals and fungicides did not become available until after WWII. Most new pesticides were discovered outside Canada, and Canadian research dealing with such chemicals has centered on determining the proper amounts to use and the most effective means and time for application.
The preferred means of protecting plants against diseases and insects is to find or produce resistant varieties. Excellent research to this end has been accomplished in Canada; eg, plant breeders have consistently been able to provide new varieties of hard red spring wheat resistant to stem rust and oat varieties resistant to crown rust. Resistance to wheat stem sawfly has been incorporated into winter wheat in western Canada.
In the control of wheat stem rust, the campaign to eradicate barberry plants, the parasite's alternative host, was as important as the development of resistant wheat varieties. Similarly, the campaign to eradicate buckthorn, the alternate host of oat crown rust, was important in crown rust control. In eastern Canada, the removal of wild apple trees has been a key in the fight against the apple maggot.
Integrated pest management for insect control involves using the smallest possible amount of insecticide and the use of predators, biological pesticides, pheromones, baits, attractants, resistant crop varieties, transgenic plants that produce Bacillus thuringiensis toxin, and physical and cultural practices. Major advances are being made in all aspects of pest management (see INSECT, BENEFICIAL).
When large-scale agriculture was introduced to Canada, the thrust was to clear all unwanted trees, plants or sod from the SOIL so that monoculture (cultivation of one type of plant) could be practised. After the disastrous loss of topsoil during drought years in western Canada and similar losses during excessively wet years in denuded rolling land elsewhere, the trend has been toward the use of more responsible AGRICULTURAL SOIL PRACTICES.
Attempts have been made to control wind erosion by maintaining sufficient straw in or on the soil and by avoiding exposure of finely divided soil to wind action (see SOIL CONSERVATION). To minimize disturbance of soil, no-till methods have been developed for many crops: the annual crop may be seeded into rye or clover which is then removed by chemical weed control before the annual crop has sprouted. Direct seeding of many crops into standing stubble is increasing in popularity in western Canada.
The practice of grassing down apple and pear orchards once they approach bearing age also helps protect soil from washing or blowing away. Perhaps the most significant addition to Canadian soil management has been the promotion of the liming of the acidic soils of eastern Canada. Once soil acidity has been substantially reduced, plants can use added nutrients more effectively.
Crop production removes vast amounts of essential nutrients from the soil, especially the 3 major nutrients: nitrogen, phosphorus and potassium. Legume crops, in association with the appropriate strain of nitrogen-fixing bacteria (Rhizobium, Bradyrhizobium) can symbiotically fix part of their nitrogen from the inert N2 in the air. However, other crops have a large nitrogen requirement, which must be supplied either in organic form (eg, leguminous green manure crops or livestock manures) or in inorganic form (eg, ammonium or nitrate fertilizers). Most farmers conduct soil fertility tests to assist them in determining the proper rate and type of nutrient to apply for optimum yields.
An important practice in annual crop production is crop rotation. Annual recropping to the same crop results in rapid buildup of pest problems (disease and insects) specific to that crop. A planned sequence of crops greatly assists in reducing pest problems. Nitrogen-fixing legumes in particular benefit the succeeding nonlegume crop by providing a small nitrogen carryover benefit plus a nonnitrogen benefit (rotation effect), which results in a higher yield of the nonlegume crop. This rotation effect may be due to the general suppression of disease levels in the following crop.
Food crops are important, but so are forage crops. Forage crops are perennial and include forage legumes (eg, alfalfa, clovers) and forage grasses (bromegrasses, wheatgrasses). Forages are used for livestock feed (hay and pasture) and provide the base for cattle, sheep, goat and horse industries. In addition, forages are vital to soil conservation and agricultural sustainability in that they are long-lived plants that help protect the soil from erosion and actually help in the soil-building process. Research has helped develop the most appropriate species and the best management system under the different environments and thus contributed to the development of a more nearly sustainable agriculture.
Research on ornamental crops has resulted in a wide range of annual flowers, winter hardy perennial flowers, turf grass species and varieties, and ornamental shrubs and trees adapted to Canadian conditions. Most crop plants, including ornamentals, were introduced into Canada and required much research on variety development and crop management to bring these crops to their current levels of adaptation and benefit to Canadians.
Native people stored grains (eg, corn), fruits (eg, cranberries) and vegetables (eg, beans, squash) for winter use. European settlers introduced other fruits (eg, apples, pears) and vegetables (eg, potatoes, cabbage, celery, turnips, onions, carrots) which required new methods of long-term storage. The first storages were of a type known as common, air or ventilated storage. Many are still in use in Canada because, after fall harvest, ambient nighttime temperatures are usually suitable for preserving potatoes, dry onions, cabbage and mature carrots.
Earlier storages were underground, but the modern trend is to locate most of the building above ground and use automatic control of louvres and fans to draw in cool, outside air when required. A few cool stores used ice to lower temperatures inside a storage room. For many years after ice-cooled stores were abandoned, ice was used to cool railway cars carrying perishable products. Mechanically refrigerated storage was a major advance, allowing many fruits and vegetables to be maintained for up to 6 months in good condition.
Fruits and vegetables not adapted to long-term storage could benefit from refrigeration for short terms, allowing marketing over an extended time. Canadian government and university research laboratories have made noteworthy advances in the science of food storage. The more recent improvements are described below.
Processing and Products
Raw agricultural products produced in Canada are valued annually at some $20 billion. Processing adds greatly to the final value and provides thousands of jobs. The FOOD AND BEVERAGE INDUSTRIES have been very innovative in creating new products (eg, new breakfast cereals). In addition, the provincial research laboratories at Vineland, Ont, and AAFC stations at Summerland and Kentville have searched for new means of processing fruits and vegetables, mainly with a view to reducing costs.
For example, the steam blancher developed at Kentville to replace hot water treatment saves energy as well as conserving the vitamin content by using a shorter blanching period. Another example is the rotated can method (roll cooker) of heat-processing tinned fruit, developed at Summerland to provide more rapid and effective heat treatment and thus to preserve the product's quality.
The Canadian WINE INDUSTRY improved rapidly following WWII with the influx of European wine-making experts and hybrid grapes from France. The AAFC research stations at Summerland and Kentville have been active in testing newly introduced grape varieties because of the desire to maintain and expand the wine-making industry in BC and NS.
Government research has also assisted the MAPLE SUGAR INDUSTRY by testing pilot plant models of a method of concentration known as reverse osmosis. In reverse osmosis a liquid under pressure is restrained by a membrane through which water molecules will pass but the molecule to be concentrated (eg, the sugar in maple sap) will not.
The AAFC research station at Kentville acquired a small flexible-retortable-pouch processor from France in 1977. The laminated plastic and foil pouches are able to withstand heat and pressure in cooking and to resist puncture during commercial handling. The advantages of processing food products in the pouch include transportation and storage savings on empty and filled containers, energy conservation during processing, and better nutritional, flavour and textural properties. The new container is likely to replace cans and bottles. Finally, byproducts of the agricultural industry are being studied as possible raw products for single-cell-protein production, at first for animal feed, but eventually for human consumption as well. Crop research is designed to assure that we have a wide choice of the safest, highest-quality food in the world at a reasonable price.
See also AGRICULTURAL RESEARCH AND DEVELOPMENT.
Jacketed storage rooms are built so that cooling air circulates around the room in a sealed envelope. Jacketed storage is especially effective for maintaining high relative humidities and is used for storing carrots, cabbage and celery.
Controlled-atmosphere storage is a system for holding produce in an atmosphere that differs substantially from air in the proportion of nitrogen, oxygen or carbon dioxide present. The original research was done mainly at AAFC laboratories at Kentville (NS), Ottawa and Summerland (BC), at NRC laboratories in Ottawa and at U of Guelph. This method is now in common use by commercial producers and processors.
Low-pressure storage involves holding products in a partial vacuum with controlled oxygen levels. The system is still largely experimental, although prototype vans are available. Pioneering work in the use of LPS for fruits and vegetables has been conducted at U of Guelph.
Ultra-low-oxygen storage is the most successful development in apple storage since controlled-atmosphere storage began. It reduces oxygen from 5% to a range of 0.5-1.5% and also lowers carbon dioxide levels. The altered composition of the atmosphere slows the ripening process; thus, the system allows marketing over a year after harvest, with little loss of original flavour and texture. Canadian experiments on ultra-low-oxygen storage began in Kentville in 1976, following initial work conducted in the UK.
Tissue culture is the growing of complete plants from individual cells, small groups of cells, tissue explants and isolated apical or axillary buds. Since many new plants can be produced from a small amount of starting material, it is possible to produce large numbers of cloned plants (ie, all individuals are genetically identical). Clonal lowbush blueberry plants and apple seedlings have been produced by tissue culture at the Kentville, NS, Research Station of AAFC.
Methods for in vitro propagation of a number of ornamental plants have been developed at the University of New Brunswick, Fredericton, and the University of Guelph. Similarly, grapes and kiwi fruit have been propagated at BC's Saanichton research station.
In addition several Canadian laboratories are conducting research on the tissue culture of conifers. These include the Canadian Forest Service laboratories at Fredericton, NB, and Laurentian Hills, Ont, and the research labs at Queen's in Kingston and at the University of Calgary.
Tissue culture techniques are also used in plant BIOTECHNOLOGY and genetic transformation studies designed to produce transgenic varieties; ie, varieties carrying desired genes from another genus. An example is "Roundup ready" canola, a type of canola that has been transformed by the insertion of a gene causing resistance to Roundup (trade name of glyphosate), a herbicide that kills most annual plants unless they carry this gene.
Plant biochemistry research is also involved in the development and maintenance of quality standards in our foods. The plant breeder works in conjunction with a plant biochemist to make sure that the new higher-yielding, disease-resistant varieties also meet or exceed prescribed quality standards. This helps assure that new varieties, new crops and new food products will not harm the consumer.
Weed-control research is conducted by the agricultural colleges of various universities, by chemical companies and by the AAFC. Recently, emphasis has been placed on integrated weed control with reduced herbicide applications and weed control systems for direct seeding (zero till) in annual crop production. Integrated weed control systems are the best approach to minimizing the problem associated with the increasing occurrence of weeds that are resistant to various herbicides. The mode of action of various herbicides is being studied at the biochemical level within plants.
Canadian research into the relationship between the wheat plant and the stem and leaf rust organisms began in earnest with the establishment of the Dominion Rust Research Laboratory at Winnipeg in 1925. Major contributions were made by J.H. CRAIGIE, Margaret NEWTON, Thorvaldur JOHNSON, C.H. GOULDEN and others. Professor M. Shaw and his students at the University of Saskatchewan, Saskatoon, began a very productive research program on the plant physiological and biochemical aspects of the wheat rust problem in 1950. Shortly afterwards research programs were begun at the Winnipeg Rust Research Laboratory by F.R. Forsyth and at the Botany Department of the University of Manitoba by P.K. Isaac.
The Winnipeg Research Station still maintains an active program on all aspects of preventing and controlling the harmful effects of the rusts of wheat, barley, oat, flax and sunflower. The main importance of this work was a better understanding of the physiological and biochemical interactions of the rust fungus and the wheat plant. The simultaneous studies on the genetics of wheat and the rusts have resulted in a steady production by the plant breeders of rust-resistant varieties. This has eliminated devastating rust epidemics since 1952.
Much research is concentrated on the genetics of the host-pathogen system for many crop diseases, including the effects of races of the pathogen, major gene and minor gene effects, environmental effects, the host resistance gene, pathogen virulence gene relationship, horizontal resistance and vertical resistance.
Other noteworthy achievements include the outstanding work on the physiology and biochemistry of lignin (a substance related to cellulose) and edible seaweeds at the NRC laboratories at Ottawa and Halifax respectively, and the pionering work in GENETIC ENGINEERING done by O. Gamborg at NRC's Prairie Regional Laboratory (now the Plant Biotechnology Institute) in the 1960s and 1970s.