In vascular plants , the roots are the organs of a plant that are modified to provide anchorage for the plant and take in water and nutrients into the plant body, which allows plants to grow taller and faster. They are most often below the surface of the soil , but roots can also be aerial or aerating, that is, growing up above the ground or especially above water.
133-475: Wheat is a grass widely cultivated for its seed , a cereal grain that is a staple food around the world. The many species of wheat together make up the genus Triticum ( / ˈ t r ɪ t ɪ k ə m / ); the most widely grown is common wheat ( T. aestivum ). The archaeological record suggests that wheat was first cultivated in the regions of the Fertile Crescent around 9600 BC. Botanically,
266-403: A primary root and secondary roots (or lateral roots ). The roots, or parts of roots, of many plant species have become specialized to serve adaptive purposes besides the two primary functions , described in the introduction. The distribution of vascular plant roots within soil depends on plant form, the spatial and temporal availability of water and nutrients, and the physical properties of
399-499: A sod -forming perennial grass used in agriculture is Thinopyrum intermedium . Grasses are used as raw material for a multitude of purposes, including construction and in the composition of building materials such as cob , for insulation, in the manufacture of paper and board such as oriented structural straw board . Grass fiber can be used for making paper , biofuel production, nonwoven fabrics, and as replacement for glass fibers used in reinforced plastics. Bamboo scaffolding
532-571: A central agriculture endeavor in the worldwide British Empire in the 19th century, and remains of great importance in Australia, Canada and India. In Australia, with vast lands and a limited work force, expanded production depended on technological advances, especially regarding irrigation and machinery. By the 1840s there were 900 growers in South Australia . They used "Ridley's Stripper", a reaper-harvester perfected by John Ridley in 1843, to remove
665-433: A combination of artificial and natural selection . This complexity and diversity of status has led to much confusion in the naming of wheats. Hexaploid species (6N) Tetraploid species (4N) Diploid species (2N) The wild species of wheat, along with the domesticated varieties einkorn , emmer and spelt , have hulls. This more primitive morphology (in evolutionary terms) consists of toughened glumes that tightly enclose
798-412: A component of the vascular cylinder. The vascular cambium produces new layers of secondary xylem annually. The xylem vessels are dead at maturity (in some) but are responsible for most water transport through the vascular tissue in stems and roots. Tree roots usually grow to three times the diameter of the branch spread, only half of which lie underneath the trunk and canopy. The roots from one side of
931-525: A decline in climate resilience of wheat has been observed. Hunter-gatherers in West Asia harvested wild wheats for thousands of years before they were domesticated , perhaps as early as 21,000 BC, but they formed a minor component of their diets. In this phase of pre-domestication cultivation, early cultivars were spread around the region and slowly developed the traits that came to characterise their domesticated forms. Repeated harvesting and sowing of
1064-408: A good crop of grain. The farmer may intervene while the crop is growing to add fertilizer , water by irrigation , or pesticides such as herbicides to kill broad-leaved weeds or insecticides to kill insect pests. The farmer may assess soil minerals, soil water, weed growth, or the arrival of pests to decide timely and cost-effective corrective actions, and crop ripeness and water content to select
1197-485: A less reliable method based on grain size. Einkorn and emmer are considered two of the founder crops cultivated by the first farming societies in Neolithic West Asia. These communities also cultivated naked wheats ( T. aestivum and T. durum ) and a now-extinct domesticated form of Zanduri wheat ( T. timopheevii ), as well as a wide variety of other cereal and non-cereal crops. Wheat was relatively uncommon for
1330-448: A lesser extent other parts of the root, then also to the shoot and grain. Calcium transport from the apical segment is slower, mostly transported upward and accumulated in stem and shoot. Researchers found that partial deficiencies of K or P did not change the fatty acid composition of phosphatidyl choline in Brassica napus L. plants. Calcium deficiency did, on the other hand, lead to
1463-670: A low quality for human nutrition, according to the DIAAS protein quality evaluation method. Though they contain adequate amounts of the other essential amino acids, at least for adults, wheat proteins are deficient in the essential amino acid lysine . Because the proteins present in the wheat endosperm (gluten proteins) are particularly poor in lysine, white flours are more deficient in lysine compared with whole grains. Significant efforts in plant breeding are made to develop lysine-rich wheat varieties, without success, as of 2017. Supplementation with proteins from other food sources (mainly legumes )
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#17328517007581596-431: A major component of woody plant tissues and many nonwoody plants. For example, storage roots of sweet potato have secondary growth but are not woody. Secondary growth occurs at the lateral meristems , namely the vascular cambium and cork cambium . The former forms secondary xylem and secondary phloem , while the latter forms the periderm . In plants with secondary growth, the vascular cambium, originating between
1729-447: A major contribution to the nutritional welfare of the poor. Some wheat species are diploid , with two sets of chromosomes , but many are stable polyploids , with four sets of chromosomes ( tetraploid ) or six ( hexaploid ). Einkorn wheat ( Triticum monococcum ) is diploid (AA, two complements of seven chromosomes, 2n=14). Most tetraploid wheats (e.g. emmer and durum wheat) are derived from wild emmer , T. dicoccoides . Wild emmer
1862-474: A major contributor to increased grain output. More widely over the last 40 years, a massive increase in fertilizer use together with the increased availability of semi-dwarf varieties in developing countries, has greatly increased yields per hectare. In developing countries, use of (mainly nitrogenous) fertilizer increased 25-fold in this period. However, farming systems rely on much more than fertilizer and breeding to improve productivity. A good illustration of this
1995-637: A marked decline of polyunsaturated compounds that would be expected to have negative impacts for integrity of the plant membrane , that could effect some properties like its permeability, and is needed for the ion uptake activity of the root membranes. The term root crops refers to any edible underground plant structure, but many root crops are actually stems, such as potato tubers. Edible roots include cassava , sweet potato , beet , carrot , rutabaga , turnip , parsnip , radish , yam and horseradish . Spices obtained from roots include sassafras , angelica , sarsaparilla and licorice . Sugar beet
2128-498: A nearby plant was exposed to drought conditions. Since nearby plants showed no changes in stomatal aperture researchers believe the drought signal spread through the roots and soil, not through the air as a volatile chemical signal. Soil microbiota can suppress both disease and beneficial root symbionts (mycorrhizal fungi are easier to establish in sterile soil). Inoculation with soil bacteria can increase internode extension, yield and quicken flowering. The migration of bacteria along
2261-577: A photosynthetic pathway, linked to specialized Kranz leaf anatomy , which allows for increased water use efficiency , rendering them better adapted to hot, arid environments. The C3 grasses are referred to as "cool-season" grasses, while the C4 plants are considered "warm-season" grasses. Although the C4 species are all in the PACMAD clade (see diagram below), it seems that various forms of C4 have arisen some twenty or more times, in various subfamilies or genera. In
2394-399: A plant's root system. This system can be extremely complex and is dependent upon multiple factors such as the species of the plant itself, the composition of the soil and the availability of nutrients. Root architecture plays the important role of providing a secure supply of nutrients and water as well as anchorage and support. The configuration of root systems serves to structurally support
2527-481: A protein content of about 13%, which is relatively high compared to other major cereals but relatively low in protein quality (supplying essential amino acids ). When eaten as the whole grain , wheat is a source of multiple nutrients and dietary fiber . In a small part of the general population, gluten – which comprises most of the protein in wheat – can trigger coeliac disease , noncoeliac gluten sensitivity , gluten ataxia , and dermatitis herpetiformis . Wheat
2660-428: A range of features. The evolutionary development of roots likely happened from the modification of shallow rhizomes (modified horizontal stems) which anchored primitive vascular plants combined with the development of filamentous outgrowths (called rhizoids ) which anchored the plants and conducted water to the plant from the soil. Light has been shown to have some impact on roots, but its not been studied as much as
2793-482: A root system are: All components of the root architecture are regulated through a complex interaction between genetic responses and responses due to environmental stimuli. These developmental stimuli are categorised as intrinsic, the genetic and nutritional influences, or extrinsic, the environmental influences and are interpreted by signal transduction pathways . Extrinsic factors affecting root architecture include gravity, light exposure, water and oxygen, as well as
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#17328517007582926-402: A signal as to how fast the shoots can grow. Roots often function in storage of food and nutrients. The roots of most vascular plant species enter into symbiosis with certain fungi to form mycorrhizae , and a large range of other organisms including bacteria also closely associate with roots. In its simplest form, the term root system architecture (RSA) refers to the spatial configuration of
3059-543: A significant variable cost in wheat production. Estimates of the amount of wheat production lost owing to plant diseases vary between 10 and 25% in Missouri. A wide range of organisms infect wheat, of which the most important are viruses and fungi. Poaceae Gramineae Juss. Poaceae ( / p oʊ ˈ eɪ s i . iː , - s i aɪ / poh- AY -see-e(y)e ), also called Gramineae ( / ɡ r ə ˈ m ɪ n i . iː , - n i aɪ / grə- MIN -ee-e(y)e ),
3192-596: A smaller part of the vegetation in almost every other terrestrial habitat. Grass-dominated biomes are called grasslands. If only large, contiguous areas of grasslands are counted, these biomes cover 31% of the planet's land. Grasslands include pampas , steppes , and prairies . Grasses provide food to many grazing mammals, as well as to many species of butterflies and moths . Many types of animals eat grass as their main source of food, and are called graminivores – these include cattle , sheep , horses , rabbits and many invertebrates , such as grasshoppers and
3325-466: A source of straw , which could be used for fuel, wicker-making , or wattle and daub construction. Domestic wheat was quickly spread to regions where its wild ancestors did not grow naturally. Emmer was introduced to Cyprus as early as 8600 BC and einkorn c. 7500 BC ; emmer reached Greece by 6500 BC, Egypt shortly after 6000 BC, and Germany and Spain by 5000 BC. "The early Egyptians were developers of bread and
3458-804: A tree usually supply nutrients to the foliage on the same side. Some families however, such as Sapindaceae (the maple family), show no correlation between root location and where the root supplies nutrients on the plant. There is a correlation of roots using the process of plant perception to sense their physical environment to grow, including the sensing of light, and physical barriers. Plants also sense gravity and respond through auxin pathways, resulting in gravitropism . Over time, roots can crack foundations, snap water lines, and lift sidewalks. Research has shown that roots have ability to recognize 'self' and 'non-self' roots in same soil environment. The correct environment of air , mineral nutrients and water directs plant roots to grow in any direction to meet
3591-904: A variety that include grasses that are related to modern rice and bamboo . Grasses have adapted to conditions in lush rain forests , dry deserts , cold mountains and even intertidal habitats , and are currently the most widespread plant type; grass is a valuable source of food and energy for all sorts of wildlife. A cladogram shows subfamilies and approximate species numbers in brackets: Chloridoideae (1600) Danthonioideae (300) Micrairoideae (200) Arundinoideae (50) Panicoideae (3250) Aristidoideae (350) Oryzoideae (110) Bambusoideae – bamboos (1450) Pooideae (3850) Puelioideae (11) Pharoideae (13) Anomochlooideae (4) Before 2005, fossil findings indicated that grasses evolved around 55 million years ago. Finds of grass-like phytoliths in Cretaceous dinosaur coprolites from
3724-425: A viable crop. When the use of seed drills replaced broadcasting sowing of seed in the 18th century, another great increase in productivity occurred. Yields of pure wheat per unit area increased as methods of crop rotation were applied to land that had long been in cultivation, and the use of fertilizers became widespread. Improved agricultural husbandry has more recently included pervasive automation , starting with
3857-500: A year's supply. Wheat grain was stored after threshing , with the chaff removed. It was then processed into flour using ground stone mortars . Bread made from ground einkorn and the tubers of a form of club rush ( Bolboschoenus glaucus ) was made as early as 12,400 BC. At Çatalhöyük ( c. 7100–6000 BC ), both wholegrain wheat and flour was used to prepare bread, porridge and gruel . Apart from food, wheat may also have been important to Neolithic societies as
3990-451: Is Australian wheat growing in the southern winter cropping zone, where, despite low rainfall (300 mm), wheat cropping is successful even with relatively little use of nitrogenous fertilizer. This is achieved by crop rotation with leguminous pastures. The inclusion of a canola crop in the rotations has boosted wheat yields by a further 25%. In these low rainfall areas, better use of available soil-water (and better control of soil erosion)
4123-473: Is a grass used as a culinary herb for its citrus-like flavor and scent. Many species of grass are grown as pasture for foraging or as fodder for prescribed livestock feeds, particularly in the case of cattle , horses , and sheep . Such grasses may be cut and stored for later feeding, especially for the winter, in the form of bales of hay or straw , or in silos as silage . Straw (and sometimes hay) may also be used as bedding for animals. An example of
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4256-465: Is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses . It includes the cereal grasses, bamboos , the grasses of natural grassland and species cultivated in lawns and pasture . The latter are commonly referred to collectively as grass . With around 780 genera and around 12,000 species, the Poaceae is the fifth-largest plant family , following
4389-564: Is a rich source (20% or more of the Daily Value , DV) of multiple dietary minerals , such as manganese , phosphorus , magnesium , zinc , and iron (table). The B vitamins , niacin (36% DV), thiamine (33% DV), and vitamin B6 (23% DV), are present in significant amounts (table). Wheat is a significant source of vegetable proteins in human food, having a relatively high protein content compared to other major cereals. However, wheat proteins have
4522-446: Is a stout grass of medium to tall height. Its stem is jointed and usually hollow, forming a straw. There can be many stems on one plant. It has long narrow leaves, their bases sheathing the stem, one above each joint. At the top of the stem is the flower head, containing some 20 to 100 flowers. Each flower contains both male and female parts. The flowers are wind-pollinated , with over 99% of pollination events being self-pollinations and
4655-566: Is able to withstand typhoon-force winds that would break steel scaffolding. Larger bamboos and Arundo donax have stout culms that can be used in a manner similar to timber, Arundo is used to make reeds for woodwind instruments , and bamboo is used for innumerable implements. Phragmites australis (common reed) is important for thatching and wall construction of homes in Africa. Grasses are used in water treatment systems, in wetland conservation and land reclamation , and used to lessen
4788-453: Is achieved by retaining the stubble after harvesting and by minimizing tillage. Pests and diseases consume 21.47% of the world's wheat crop annually. There are many wheat diseases, mainly caused by fungi, bacteria, and viruses . Plant breeding to develop new disease-resistant varieties, and sound crop management practices are important for preventing disease. Fungicides, used to prevent the significant crop losses from fungal disease, can be
4921-455: Is also important to identify periods of higher risk from the climate. Farmers benefit from knowing when the 'flag leaf' (last leaf) appears, as this leaf represents about 75% of photosynthesis reactions during the grain filling period, and so should be preserved from disease or insect attacks to ensure a good yield. Several systems exist to identify crop stages, with the Feekes and Zadoks scales being
5054-589: Is an important source of sugar. Yam roots are a source of estrogen compounds used in birth control pills . The fish poison and insecticide rotenone is obtained from roots of Lonchocarpus spp. Important medicines from roots are ginseng , aconite , ipecac , gentian and reserpine . Several legumes that have nitrogen-fixing root nodules are used as green manure crops, which provide nitrogen fertilizer for other crops when plowed under. Specialized bald cypress roots, termed knees, are sold as souvenirs, lamp bases and carved into folk art. Native Americans used
5187-416: Is called an ear. Leaves emerge from the shoot apical meristem in a telescoping fashion until the transition to reproduction i.e. flowering. The last leaf produced by a wheat plant is known as the flag leaf. It is denser and has a higher photosynthetic rate than other leaves, to supply carbohydrate to the developing ear. In temperate countries the flag leaf, along with the second and third highest leaf on
5320-623: Is commonly used to compensate for this deficiency, since the limitation of a single essential amino acid causes the others to break down and become excreted, which is especially important during growth. Consumed worldwide by billions of people, wheat is a significant food for human nutrition, particularly in the least developed countries where wheat products are primary foods. When eaten as the whole grain , wheat supplies multiple nutrients and dietary fiber recommended for children and adults. In genetically susceptible people, wheat gluten can trigger coeliac disease . Coeliac disease affects about 1% of
5453-996: Is for piecing together historical landscapes and weather patterns, considering other factors such as genetic material amount might also affect pollen size. Despite these challenges, new techniques in Fourier-Transform Infrared Spectroscopy (FT-IR) and improved statistical methods are now helping to better identify these similar-looking pollen types. Grasses are the primary plants used in lawns, which themselves derive from grazed grasslands in Europe. They also provide an important means of erosion control (e.g., along roadsides), especially on sloping land. Grass lawns are an important covering of playing surfaces in many sports, including football (soccer) , American football , tennis , golf , cricket , softball and baseball . Root The major functions of roots are absorption of water , plant nutrition and anchoring of
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5586-466: Is in its inactive form. This stabilized transcription factor is then able to be transported to the roots of the plant through the phloem , where it proceeds to induce its own transcription as a way to amplify its signal. In the roots of the plant HY5 functions to inhibit an auxin response factor known as ARF19, a response factor responsible for the translation of PIN3 and LAX3, two well known auxin transporting proteins . Thus, through manipulation of ARF19,
5719-472: Is itself the result of a hybridization between two diploid wild grasses, T. urartu and a wild goatgrass such as Ae. speltoides . The hybridization that formed wild emmer (AABB, four complements of seven chromosomes in two groups, 4n=28) occurred in the wild, long before domestication, and was driven by natural selection . Hexaploid wheats evolved in farmers' fields as wild emmer hybridized with another goatgrass, Ae. squarrosa or Ae. tauschii , to make
5852-626: Is likely to be prioritised in drought-adapted crops, while stem non-structural carbohydrate is prioritised in varieties developed for countries where disease is a bigger issue. Depending on variety, wheat may be awned or not awned. Producing awns incurs a cost in grain number, but wheat awns photosynthesise more efficiently than their leaves with regards to water usage, so awns are much more frequent in varieties of wheat grown in hot drought-prone countries than those generally seen in temperate countries. For this reason, awned varieties could become more widely grown due to climate change . In Europe, however,
5985-436: Is limited by cooler temperatures at subsoil levels. Needs vary by plant species, but in temperate regions cool temperatures may limit root systems. Cool temperature species like oats , rapeseed , rye , wheat fare better in lower temperatures than summer annuals like maize and cotton . Researchers have found that plants like cotton develop wider and shorter taproots in cooler temperatures. The first root originating from
6118-606: Is linked to crop improvement, since meiotic recombination is an important component of plant breeding . Unlike in animals, the specification of both male and female plant germlines occurs late in development during flowering. The transition from the sporophyte phase to the gametophyte state is initiated by meiotic entry. Grasses are, in human terms, perhaps the most economically important plant family. Their economic importance stems from several areas, including food production, industry, and lawns . They have been grown as food for domesticated animals for up to 6,000 years and
6251-399: Is localized in both the root system as well as the shoot system of plants, but through knockout mutant experimentation, it was found that root localized PhyA does not sense the light ratio, whether directly or axially, that leads to changes in the lateral root architecture. Research instead found that shoot localized PhyA is the phytochrome responsible for causing these architectural changes of
6384-455: Is more diverse, with domesticated varieties falling into two major groups: hulled or non-shattering, in which threshing separates the whole spikelet ; and free-threshing, where the individual grains are separated. Both varieties probably existed in prehistory, but over time free-threshing cultivars became more common. Wild emmer was first cultivated in the southern Levant , as early as 9600 BC. Genetic studies have found that, like einkorn, it
6517-399: Is normally planted after tilling the soil by ploughing and then harrowing to kill weeds and create an even surface. The seeds are then scattered on the surface, or drilled into the soil in rows. Winter wheat lies dormant during a winter freeze. It needs to develop to a height of 10 to 15 cm before the cold intervenes, so as to be able to survive the winter; it requires a period with
6650-428: Is often called corn in countries including Britain). Since 1960, world production of wheat and other grain crops has tripled and is expected to grow further through the middle of the 21st century. Global demand for wheat is increasing because of the usefulness of gluten to the food industry. Wheat is an important source of carbohydrates . Globally, it is the leading source of vegetable proteins in human food, having
6783-590: Is regulated by a novel gene called Enhanced Gravitropism 1 (EGT1). Research indicates that plant roots growing in search of productive nutrition can sense and avoid soil compaction through diffusion of the gas ethylene . In order to avoid shade, plants utilize a shade avoidance response. When a plant is under dense vegetation, the presence of other vegetation nearby will cause the plant to avoid lateral growth and experience an increase in upward shoot, as well as downward root growth. In order to escape shade, plants adjust their root architecture, most notably by decreasing
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#17328517007586916-489: Is valuable to impart viscoelastic functional qualities in dough , enabling the preparation of diverse processed foods such as breads, noodles, and pasta that facilitate wheat consumption. Raw red winter wheat is 13% water, 71% carbohydrates including 12% dietary fiber , 13% protein , and 2% fat (table). Some 75–80% of the protein content is as gluten . In a reference amount of 100 grams (3.5 oz), wheat provides 1,368 kilojoules (327 kilocalories) of food energy and
7049-449: The Aristida genus for example, one species ( A. longifolia ) is C3 but the approximately 300 other species are C4. As another example, the whole tribe of Andropogoneae , which includes maize , sorghum , sugar cane , " Job's tears ", and bluestem grasses , is C4. Around 46 percent of grass species are C4 plants. The name Poaceae was given by John Hendley Barnhart in 1895, based on
7182-698: The Albian stage of the Early Cretaceous approximately 113–100 million years ago, which were found to belong to primitive lineages within Poaceae, similar in position to the Anomochlooideae. These are currently the oldest known grass fossils. The relationships among the three subfamilies Bambusoideae, Oryzoideae and Pooideae in the BOP clade have been resolved: Bambusoideae and Pooideae are more closely related to each other than to Oryzoideae. This separation occurred within
7315-503: The Americas ). Sugarcane is the major source of sugar production. Additional food uses of sugarcane include sprouted grain , shoots , and rhizomes , and in drink they include sugarcane juice and plant milk , as well as rum , beer , whisky , and vodka . Bamboo shoots are used in numerous Asian dishes and broths, and are available in supermarkets in various sliced forms, in both fresh, fermented and canned versions. Lemongrass
7448-550: The Asteraceae , Orchidaceae , Fabaceae and Rubiaceae . The Poaceae are the most economically important plant family, providing staple foods from domesticated cereal crops such as maize , wheat , rice , oats , barley , and millet for people and as feed for meat-producing animals . They provide, through direct human consumption, just over one-half (51%) of all dietary energy; rice provides 20%, wheat supplies 20%, maize (corn) 5.5%, and other grains 6%. Some members of
7581-453: The Cenozoic contributed to the spread of grasses. Without large grazers, fire-cleared areas are quickly colonized by grasses, and with enough rain, tree seedlings. Trees eventually outcompete most grasses. Trampling grazers kill seedling trees but not grasses. Sexual reproduction and meiosis have been studied in rice , maize , wheat and barley . Meiosis research in these crop species
7714-850: The hexaploid wheats including bread wheat . A 2007 molecular phylogeny of the wheats gives the following not fully-resolved cladogram of major cultivated species; the large amount of hybridisation makes resolution difficult. Markings like "6N" indicate the degree of polyploidy of each species: Barley 2N, rye 2N/4N, and other cereals Triticum monococcum ( einkorn ) 2N × Aegilotriticum hybrids ( Aegilops x Triticum ) 6N Triticum timopheevii (zanduri wheat) and others 4N Triticum aestivum ( common or bread wheat ) 6N Triticum durum/turgidum ( durum wheat) 4N Triticum spelta ( spelt ) 6N Triticum turanicum ( khorasan wheat ) 4N Triticum dicoccum ( emmer ) 4N many other species During 10,000 years of cultivation, numerous forms of wheat, many of them hybrids , have developed under
7847-422: The ligule lies at the junction between sheath and blade, preventing water or insects from penetrating into the sheath. Flowers of Poaceae are characteristically arranged in spikelets , each having one or more florets. The spikelets are further grouped into panicles or spikes . The part of the spikelet that bears the florets is called the rachilla. A spikelet consists of two (or sometimes fewer) bracts at
7980-513: The 20th century, global wheat output expanded by about 5-fold, but until about 1955 most of this reflected increases in wheat crop area, with lesser (about 20%) increases in crop yields per unit area. After 1955 however, there was a ten-fold increase in the rate of wheat yield improvement per year, and this became the major factor allowing global wheat production to increase. Thus technological innovation and scientific crop management with synthetic nitrogen fertilizer , irrigation and wheat breeding were
8113-562: The Poaceae are used as building materials ( bamboo , thatch , and straw ); others can provide a source of biofuel , primarily via the conversion of maize to ethanol . Grasses have stems that are hollow except at the nodes and narrow alternate leaves borne in two ranks. The lower part of each leaf encloses the stem, forming a leaf-sheath. The leaf grows from the base of the blade, an adaptation allowing it to cope with frequent grazing. Grasslands such as savannah and prairie where grasses are dominant are estimated to constitute 40.5% of
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#17328517007588246-437: The availability or lack of nitrogen, phosphorus, sulphur, aluminium and sodium chloride. The main hormones (intrinsic stimuli) and respective pathways responsible for root architecture development include: Early root growth is one of the functions of the apical meristem located near the tip of the root. The meristem cells more or less continuously divide, producing more meristem, root cap cells (these are sacrificed to protect
8379-442: The base, called glumes , followed by one or more florets. A floret consists of the flower surrounded by two bracts, one external—the lemma —and one internal—the palea . The flowers are usually hermaphroditic — maize being an important exception—and mainly anemophilous or wind-pollinated, although insects occasionally play a role. The perianth is reduced to two scales, called lodicules , that expand and contract to spread
8512-450: The caterpillars of many brown butterflies . Grasses are also eaten by omnivorous or even occasionally by primarily carnivorous animals. Grasses dominate certain biomes , especially temperate grasslands , because many species are adapted to grazing and fire. Grasses are unusual in that the meristem is near the bottom of the plant; hence, grasses can quickly recover from cropping at the top. The evolution of large grazing animals in
8645-469: The cause of non-coeliac gluten sensitivity. As of 2019, reviews have concluded that FODMAPs only explain certain gastrointestinal symptoms, such as bloating , but not the extra-digestive symptoms that people with non-coeliac gluten sensitivity may develop. Other wheat proteins, amylase-trypsin inhibitors, have been identified as the possible activator of the innate immune system in coeliac disease and non-coeliac gluten sensitivity. These proteins are part of
8778-402: The coverage was only around 37%. Before the 1970s, scientists believed that the majority of the root surface was covered by microorganisms. Researchers studying maize seedlings found that calcium absorption was greatest in the apical root segment, and potassium at the base of the root. Along other root segments absorption was similar. Absorbed potassium is transported to the root tip, and to
8911-411: The deepest of arable crops, extending as far down as 2 metres (6 ft 7 in). While the roots of a wheat plant are growing, the plant also accumulates an energy store in its stem, in the form of fructans , which helps the plant to yield under drought and disease pressure, but it has been observed that there is a trade-off between root growth and stem non-structural carbohydrate reserves. Root growth
9044-474: The domestic form comes after c. 8800 BC in southern Turkey, at Çayönü , Cafer Höyük , and possibly Nevalı Çori . Genetic evidence indicates that it was domesticated in multiple places independently. Wild emmer wheat ( T. turgidum subsp. dicoccoides ) is less widespread than einkorn, favouring the rocky basaltic and limestone soils found in the hilly flanks of the Fertile Crescent. It
9177-679: The earliest known wheat with sufficient gluten for yeasted breads was found in a granary at Assiros in Macedonia dated to 1350 BC. From the Middle East , wheat continued to spread across Europe and to the Americas in the Columbian exchange . In the British Isles, wheat straw ( thatch ) was used for roofing in the Bronze Age , and remained in common use until the late 19th century. White wheat bread
9310-497: The effect of light on other plant systems. Early research in the 1930s found that light decreased the effectiveness of Indole-3-acetic acid on adventitious root initiation. Studies of the pea in the 1950s shows that lateral root formation was inhibited by light, and in the early 1960s researchers found that light could induce positive gravitropic responses in some situations. The effects of light on root elongation has been studied for monocotyledonous and dicotyledonous plants, with
9443-830: The erosional impact of urban storm water runoff. Pollen morphology, particularly in the Poaceae family, is key to figuring out their evolutionary relationships and how environments have changed over time . Grass pollen grains, however, often look the same, making it hard to use them for detailed climate or environmental reconstructions. Grass pollen has a single pore and can vary a lot in size, from about 20 to over 100 micrometers, and this size difference has been looked into for clues about past habitats, to tell apart domesticated grasses from wild ones, and to indicate various biological features like how they perform photosynthesis , their breeding systems, and genetic complexity. Yet, there's ongoing debate about how effective pollen size
9576-430: The experiments of van Gelderen et al. (2018), they wanted to see if and how it is that the shoot of A. thaliana alters and affects root development and root architecture. To do this, they took Arabidopsis plants, grew them in agar gel , and exposed the roots and shoots to separate sources of light. From here, they altered the different wavelengths of light the shoot and root of the plants were receiving and recorded
9709-558: The farm and because of poor roads, inadequate storage technologies, inefficient supply chains and farmers' inability to bring the produce into retail markets dominated by small shopkeepers. Some 10% of total wheat production is lost at farm level, another 10% is lost because of poor storage and road networks, and additional amounts are lost at the retail level. In the Punjab region of the Indian subcontinent, as well as North China, irrigation has been
9842-456: The farmer have a detailed understanding of each stage of development in the growing plants. In particular, spring fertilizers , herbicides , fungicides , and growth regulators are typically applied only at specific stages of plant development. For example, it is currently recommended that the second application of nitrogen is best done when the ear (not visible at this stage) is about 1 cm in size (Z31 on Zadoks scale ). Knowledge of stages
9975-475: The first thousand years of the Neolithic (when barley predominated), but became a staple after around 8500 BC. Early wheat cultivation did not demand much labour. Initially, farmers took advantage of wheat's ability to establish itself in annual grasslands by enclosing fields against grazing animals and re-sowing stands after they had been harvested, without the need to systematically remove vegetation or till
10108-778: The flexible roots of white spruce for basketry. Tree roots can heave and destroy concrete sidewalks and crush or clog buried pipes. The aerial roots of strangler fig have damaged ancient Mayan temples in Central America and the temple of Angkor Wat in Cambodia . Trees stabilize soil on a slope prone to landslides . The root hairs work as an anchor on the soil. Vegetative propagation of plants via cuttings depends on adventitious root formation. Hundreds of millions of plants are propagated via cuttings annually including chrysanthemum , poinsettia , carnation , ornamental shrubs and many houseplants . Roots can also protect
10241-469: The full list of Poaceae genera . The grass family is one of the most widely distributed and abundant groups of plants on Earth . Grasses are found on every continent, including Antarctica . The Antarctic hair grass, Deschampsia antarctica is one of only two plant species native to the western Antarctic Peninsula . Grasses are the dominant vegetation in many habitats, including grassland , salt-marsh , reedswamp and steppes . They also occur as
10374-529: The general population in developed countries . The only known effective treatment is a strict lifelong gluten-free diet . While coeliac disease is caused by a reaction to wheat proteins, it is not the same as a wheat allergy . Other diseases triggered by eating wheat are non-coeliac gluten sensitivity (estimated to affect 0.5% to 13% of the general population), gluten ataxia , and dermatitis herpetiformis . Certain short-chain carbohydrates present in wheat, known as FODMAPs (mainly fructose polymers ), may be
10507-587: The glumes are fragile and the rachis tough. On threshing, the chaff breaks up, releasing the grains. Wheat grain classes are named by colour, season, and hardness. The classes used in the United States are: Wheat is a staple cereal worldwide. Raw wheat berries can be ground into flour or, using hard durum wheat only, can be ground into semolina ; germinated and dried creating malt ; crushed or cut into cracked wheat; parboiled (or steamed), dried, crushed and de-branned into bulgur also known as groats . If
10640-560: The grains of wild grasses led to the creation of domestic strains, as mutant forms ('sports') of wheat were more amenable to cultivation. In domesticated wheat, grains are larger, and the seeds (inside the spikelets ) remain attached to the ear by a toughened rachis during harvesting. In wild strains, a more fragile rachis allows the ear to shatter easily, dispersing the spikelets. Selection for larger grains and non-shattering heads by farmers might not have been deliberately intended, but simply have occurred because these traits made gathering
10773-478: The grains of grasses such as wheat , rice, maize (corn) and barley have been the most important human food crops . Grasses are also used in the manufacture of thatch , paper , fuel , clothing , insulation , timber for fencing , furniture , scaffolding and construction materials, floor matting , sports turf and baskets . Of all crops grown, 70% are grasses. Agricultural grasses grown for their edible seeds are called cereals or grains (although
10906-478: The grains, and (in domesticated wheats) a semi-brittle rachis that breaks easily on threshing. The result is that when threshed, the wheat ear breaks up into spikelets. To obtain the grain, further processing, such as milling or pounding, is needed to remove the hulls or husks. Hulled wheats are often stored as spikelets because the toughened glumes give good protection against pests of stored grain. In free-threshing (or naked) forms, such as durum wheat and common wheat,
11039-612: The heads of grain. In Canada, modern farm implements made large scale wheat farming possible from the late 1840s. By 1879, Saskatchewan was the center, followed by Alberta , Manitoba and Ontario , as the spread of railway lines allowed easy exports to Britain. By 1910, wheat made up 22% of Canada's exports, rising to 25% in 1930 despite the sharp decline in prices during the worldwide Great Depression . Efforts to expand wheat production in South Africa, Kenya and India were stymied by low yields and disease. However, by 2000 India had become
11172-463: The high energy required to fix nitrogen from the atmosphere, the bacteria take carbon compounds from the plant to fuel the process. In return, the plant takes nitrogen compounds produced from ammonia by the bacteria. Soil temperature is a factor that effects root initiation and length. Root length is usually impacted more dramatically by temperature than overall mass, where cooler temperatures tend to cause more lateral growth because downward extension
11305-459: The land area of the Earth , excluding Greenland and Antarctica . Grasses are also an important part of the vegetation in many other habitats, including wetlands , forests and tundra . Though they are commonly called "grasses", groups such as the seagrasses , rushes and sedges fall outside this family. The rushes and sedges are related to the Poaceae, being members of the order Poales , but
11438-529: The lateral root density, amount of lateral roots, and the general architecture of the lateral roots. To identify the function of specific photoreceptors, proteins, genes, and hormones, they utilized various Arabidopsis knockout mutants and observed the resulting changes in lateral roots architecture. Through their observations and various experiments, van Gelderen et al. were able to develop a mechanism for how root detection of Red to Far-red light ratios alter lateral root development. A true root system consists of
11571-401: The lateral root. Research has also found that phytochrome completes these architectural changes through the manipulation of auxin distribution in the root of the plant. When a low enough Red to Far Red ratio is sensed by PhyA, the phyA in the shoot will be mostly in its active form. In this form, PhyA stabilize the transcription factor HY5 causing it to no longer be degraded as it is when phyA
11704-453: The latest Cretaceous ( Maastrichtian ) aged Lameta Formation of India have pushed this date back to 66 million years ago. In 2011, fossils from the same deposit were found to belong to the modern rice tribe Oryzeae , suggesting substantial diversification of major lineages by this time. In 2018, a study described grass microfossils extracted from the teeth of the hadrosauroid dinosaur Equijubus normani from northern China, dating to
11837-615: The latter term, when used agriculturally, refers to both cereals and similar seeds of other plant species, such as buckwheat and legumes ). Three cereals—rice, wheat, and maize (corn)—provide more than half of all calories consumed by humans. Cereals constitute the major source of carbohydrates for humans and perhaps the major source of protein; these include rice (in southern and eastern Asia ), maize (in Central and South America ), and wheat and barley (in Europe , northern Asia and
11970-463: The leaves are attached. Grass leaves are nearly always alternate and distichous (in one plane), and have parallel veins. Each leaf is differentiated into a lower sheath hugging the stem and a blade with entire (i.e., smooth) margins. The leaf blades of many grasses are hardened with silica phytoliths , which discourage grazing animals; some, such as sword grass , are sharp enough to cut human skin. A membranous appendage or fringe of hairs called
12103-469: The lemma and palea; these are generally interpreted to be modified sepals. The fruit of grasses is a caryopsis , in which the seed coat is fused to the fruit wall. A tiller is a leafy shoot other than the first shoot produced from the seed. Grass blades grow at the base of the blade and not from elongated stem tips. This low growth point evolved in response to grazing animals and allows grasses to be grazed or mown regularly without severe damage to
12236-497: The length and amount of lateral roots emerging from the primary root. Experimentation of mutant variants of Arabidopsis thaliana found that plants sense the Red to Far Red light ratio that enters the plant through photoreceptors known as phytochromes . Nearby plant leaves will absorb red light and reflect far-red light, which will cause the ratio red to far red light to lower. The phytochrome PhyA that senses this Red to Far Red light ratio
12369-399: The level and activity of auxin transporters PIN3 and LAX3 is inhibited. Once inhibited, auxin levels will be low in areas where lateral root emergence normally occurs, resulting in a failure for the plant to have the emergence of the lateral root primordium through the root pericycle . With this complex manipulation of Auxin transport in the roots, lateral root emergence will be inhibited in
12502-475: The main drivers of wheat output growth in the second half of the century. There were some significant decreases in wheat crop area, for instance in North America. Better seed storage and germination ability (and hence a smaller requirement to retain harvested crop for next year's seed) is another 20th-century technological innovation. In Medieval England, farmers saved one-quarter of their wheat harvest as seed for
12635-416: The majority of studies finding that light inhibited root elongation, whether pulsed or continuous. Studies of Arabidopsis in the 1990s showed negative phototropism and inhibition of the elongation of root hairs in light sensed by phyB . Certain plants, namely Fabaceae , form root nodules in order to associate and form a symbiotic relationship with nitrogen-fixing bacteria called rhizobia . Owing to
12768-435: The meristem), and undifferentiated root cells. The latter become the primary tissues of the root, first undergoing elongation, a process that pushes the root tip forward in the growing medium. Gradually these cells differentiate and mature into specialized cells of the root tissues. Growth from apical meristems is known as primary growth , which encompasses all elongation. Secondary growth encompasses all growth in diameter,
12901-479: The most striking characteristic of roots that distinguishes them from other plant organs such as stem-branches and leaves is that roots have an endogenous origin, i.e. , they originate and develop from an inner layer of the mother axis, such as pericycle . In contrast, stem-branches and leaves are exogenous , i.e. , they start to develop from the cortex, an outer layer. In response to the concentration of nutrients, roots also synthesise cytokinin , which acts as
13034-566: The most widely used. Each scale is a standard system which describes successive stages reached by the crop during the agricultural season. For example, the stage of pollen formation from the mother cell, and the stages between anthesis and maturity, are susceptible to high temperatures, and this adverse effect is made worse by water stress. Technological advances in soil preparation and seed placement at planting time, use of crop rotation and fertilizers to improve plant growth, and advances in harvesting methods have all combined to promote wheat as
13167-471: The next crop, leaving only three-quarters for food and feed consumption. By 1999, the global average seed use of wheat was about 6% of output. In the 21st century, rising temperatures associated with global warming are reducing wheat yield in several locations. Wheat is an annual crop. It can be planted in autumn and harvested in early summer as winter wheat in climates that are not too severe, or planted in spring and harvested in autumn as spring wheat. It
13300-469: The plant body to the ground. Root morphology is divided into four zones: the root cap , the apical meristem , the elongation zone, and the hair. The root cap of new roots helps the root penetrate the soil. These root caps are sloughed off as the root goes deeper creating a slimy surface that provides lubrication. The apical meristem behind the root cap produces new root cells that elongate. Then, root hairs form that absorb water and mineral nutrients from
13433-481: The plant's natural defense against insects and may cause intestinal inflammation in humans. In 2022, world wheat production was 808.4 million tonnes, led by China, India, and Russia which collectively provided 43.22% of the world total. As of 2019, the largest exporters were Russia (32 million tonnes), United States (27), Canada (23) and France (20), while the largest importers were Indonesia (11 million tonnes), Egypt (10.4) and Turkey (10.0). In 2021, wheat
13566-472: The plant's needs. Roots will shy or shrink away from dry or other poor soil conditions. Gravitropism directs roots to grow downward at germination , the growth mechanism of plants that also causes the shoot to grow upward. Different types of roots such as primary, seminal, lateral and crown are maintained at different gravitropic setpoint angles i.e. the direction in which they grow. Recent research show that root angle in cereal crops such as barley and wheat
13699-409: The plant, compete with other plants and for uptake of nutrients from the soil. Roots grow to specific conditions, which, if changed, can impede a plant's growth. For example, a root system that has developed in dry soil may not be as efficient in flooded soil, yet plants are able to adapt to other changes in the environment, such as seasonal changes. The main terms used to classify the architecture of
13832-574: The plant, supply the majority of carbohydrate in the grain and their condition is paramount to yield formation. Wheat is unusual among plants in having more stomata on the upper ( adaxial ) side of the leaf, than on the under ( abaxial ) side. It has been theorised that this might be an effect of it having been domesticated and cultivated longer than any other plant. Winter wheat generally produces up to 15 leaves per shoot and spring wheat up to 9 and winter crops may have up to 35 tillers (shoots) per plant (depending on cultivar). Wheat roots are among
13965-400: The plant. Three general classifications of growth habit present in grasses: bunch-type (also called caespitose), stoloniferous , and rhizomatous . The success of the grasses lies in part in their morphology and growth processes and in part in their physiological diversity. There are both C3 and C4 grasses, referring to the photosynthetic pathway for carbon fixation. The C4 grasses have
14098-460: The raw wheat is broken into parts at the mill, as is usually done, the outer husk or bran can be used in several ways. Wheat is a major ingredient in such foods as bread , porridge , crackers , biscuits , muesli , pancakes , pasta , pies , pastries , pizza , semolina , cakes , cookies , muffins , rolls , doughnuts , gravy , beer , vodka , boza (a fermented beverage ), and breakfast cereals . In manufacturing wheat products, gluten
14231-622: The relatively short time span of about 4 million years. According to Lester Charles King , the spread of grasses in the Late Cenozoic would have changed patterns of hillslope evolution favouring slopes that are convex upslope and concave downslope and lacking a free face were common. King argued that this was the result of more slowly acting surface wash caused by carpets of grass which in turn would have resulted in relatively more soil creep . There are about 12,000 grass species in about 771 genera that are classified into 12 subfamilies. See
14364-414: The rest cross-pollinations . The flower is housed in a pair of small leaflike glumes . The two (male) stamens and (female) stigmas protrude outside the glumes. The flowers are grouped into spikelets , each with between two and six flowers. Each fertilised carpel develops into a wheat grain or berry; botanically a fruit , it is often called a seed. The grains ripen to a golden yellow; a head of grain
14497-450: The results these mutations had on the root architecture, protein presence, and gene expression. To do this, Salisbury et al. used GFP fluorescence along with other forms of both macro and microscopic imagery to observe any changes various mutations caused. From these research, Salisbury et al. were able to theorize that shoot located phytochromes alter auxin levels in roots, controlling lateral root development and overall root architecture. In
14630-451: The right moment to harvest. Harvesting involves reaping , cutting the stems to gather the crop; and threshing , breaking the ears to release the grain; both steps are carried out by a combine harvester . The grain is then dried so that it can be stored safe from mould fungi. Wheat normally needs between 110 and 130 days between sowing and harvest, depending upon climate, seed type, and soil conditions. Optimal crop management requires that
14763-451: The root varies with natural soil conditions. For example, research has found that the root systems of wheat seeds inoculated with Azotobacter showed higher populations in soils favorable to Azotobacter growth. Some studies have been unsuccessful in increasing the levels of certain microbes (such as P. fluorescens ) in natural soil without prior sterilization. Grass root systems are beneficial at reducing soil erosion by holding
14896-513: The roots and the root will instead elongate downwards, promoting vertical plant growth in an attempt to avoid shade. Research of Arabidopsis has led to the discovery of how this auxin mediated root response works. In an attempt to discover the role that phytochrome plays in lateral root development, Salisbury et al. (2007) worked with Arabidopsis thaliana grown on agar plates. Salisbury et al. used wild type plants along with varying protein knockout and gene knockout Arabidopsis mutants to observe
15029-412: The seagrasses are members of the order Alismatales . However, all of them belong to the monocot group of plants. Grasses may be annual or perennial herbs , generally with the following characteristics (the image gallery can be used for reference): The stems of grasses, called culms , are usually cylindrical (more rarely flattened, but not 3-angled) and are hollow, plugged at the nodes , where
15162-504: The second largest producer of wheat in the world. In the 19th century the American wheat frontier moved rapidly westward. By the 1880s 70% of American exports went to British ports. The first successful grain elevator was built in Buffalo in 1842. The cost of transport fell rapidly. In 1869 it cost 37 cents to transport a bushel of wheat from Chicago to Liverpool . In 1905 it was 10 cents. In
15295-475: The secondary phloem including the epidermis and cortex, in many cases tend to be pushed outward and are eventually "sloughed off" (shed). At this point, the cork cambium begins to form the periderm, consisting of protective cork cells. The walls of cork cells contains suberin thickenings, which is an extra cellular complex biopolymer. The suberin thickenings functions by providing a physical barrier, protection against pathogens and by preventing water loss from
15428-488: The seed usually has a wider diameter than root branches, so smaller root diameters are expected if temperatures increase root initiation. Root diameter also decreases when the root elongates. Plants can interact with one another in their environment through their root systems. Studies have demonstrated that plant-plant interaction occurs among root systems via the soil as a medium. Researchers have tested whether plants growing in ambient conditions would change their behavior if
15561-511: The seeds easier; nevertheless such 'incidental' selection was an important part of crop domestication . As the traits that improve wheat as a food source involve the loss of the plant's natural seed dispersal mechanisms, highly domesticated strains of wheat cannot survive in the wild. Wild einkorn wheat ( T. monococcum subsp. boeoticum ) grows across Southwest Asia in open parkland and steppe environments. It comprises three distinct races , only one of which, native to Southeast Anatolia ,
15694-448: The soil together. Perennial grasses that grow wild in rangelands contribute organic matter to the soil when their old roots decay after attacks by beneficial fungi , protozoa , bacteria, insects and worms release nutrients. Scientists have observed significant diversity of the microbial cover of roots at around 10 percent of three week old root segments covered. On younger roots there was even low coverage, but even on 3-month-old roots
15827-405: The soil. The first root in seed producing plants is the radicle , which expands from the plant embryo after seed germination. When dissected, the arrangement of the cells in a root is root hair , epidermis , epiblem , cortex , endodermis , pericycle and, lastly, the vascular tissue in the centre of a root to transport the water absorbed by the root to other places of the plant. Perhaps
15960-496: The soil. The deepest roots are generally found in deserts and temperate coniferous forests; the shallowest in tundra, boreal forest and temperate grasslands. The deepest observed living root, at least 60 metres (200 ft) below the ground surface, was observed during the excavation of an open-pit mine in Arizona, US. Some roots can grow as deep as the tree is high. The majority of roots on most plants are however found relatively close to
16093-430: The soil. They may also have exploited natural wetlands and floodplains to practice décrue farming , sowing seeds in the soil left behind by receding floodwater. It was harvested with stone-bladed sickles . The ease of storing wheat and other cereals led farming households to become gradually more reliant on it over time, especially after they developed individual storage facilities that were large enough to hold more than
16226-515: The surface where nutrient availability and aeration are more favourable for growth. Rooting depth may be physically restricted by rock or compacted soil close below the surface, or by anaerobic soil conditions. The fossil record of roots—or rather, infilled voids where roots rotted after death—spans back to the late Silurian , about 430 million years ago. Their identification is difficult, because casts and molds of roots are so similar in appearance to animal burrows. They can be discriminated using
16359-410: The surrounding tissues. In addition, it also aids the process of wound healing in plants. It is also postulated that suberin could be a component of the apoplastic barrier (present at the outer cell layers of roots) which prevents toxic compounds from entering the root and reduces radial oxygen loss (ROL) from the aerenchyma during waterlogging. In roots, the cork cambium originates in the pericycle ,
16492-405: The temperature at or near freezing, its dormancy then being broken by the thaw or rise in temperature. Spring wheat does not undergo dormancy. Wheat requires a deep soil , preferably a loam with organic matter, and available minerals including soil nitrogen, phosphorus, and potassium. An acid and peaty soil is not suitable. Wheat needs some 30 to 38 cm of rain in the growing season to form
16625-459: The tribe Poeae described in 1814 by Robert Brown , and the type genus Poa described in 1753 by Carl Linnaeus . The term is derived from the Ancient Greek πόα (póa, "fodder") . Grasses include some of the most versatile plant life-forms . They became widespread toward the end of the Cretaceous period, and fossilized dinosaur dung ( coprolites ) have been found containing phytoliths of
16758-597: The use of threshing machines , and progressing to large and costly machines like the combine harvester which greatly increased productivity. At the same time, better varieties such as Norin 10 wheat , developed in Japan in the 1930s, or the dwarf wheat developed by Norman Borlaug in the Green Revolution , greatly increased yields. In addition to gaps in farming system technology and knowledge, some large wheat grain-producing countries have significant losses after harvest at
16891-525: The use of the oven and developed baking into one of the first large-scale food production industries." By 4000 BC, wheat had reached the British Isles and Scandinavia . Wheat likely appeared in China 's lower Yellow River around 2600 BC. The oldest evidence for hexaploid wheat has been confirmed through DNA analysis of wheat seeds, dating to around 6400–6200 BC, recovered from Çatalhöyük . As of 2023,
17024-455: The wheat kernel is a caryopsis , a type of fruit . Wheat is grown on a larger area of land than any other food crop (220.7 million hectares or 545 million acres in 2021). World trade in wheat is greater than for all other crops combined. In 2021, world wheat production was 771 million tonnes (850 million short tons), making it the second most-produced cereal after maize (known as corn in North America and Australia; wheat
17157-413: The xylem and the phloem, forms a cylinder of tissue along the stem and root. The vascular cambium forms new cells on both the inside and outside of the cambium cylinder, with those on the inside forming secondary xylem cells, and those on the outside forming secondary phloem cells. As secondary xylem accumulates, the "girth" (lateral dimensions) of the stem and root increases. As a result, tissues beyond
17290-455: Was domesticated in southeastern Anatolia, but only once. The earliest secure archaeological evidence for domestic emmer comes from Çayönü, c. 8300–7600 BC , where distinctive scars on the spikelets indicated that they came from a hulled domestic variety. Slightly earlier finds have been reported from Tell Aswad in Syria, c. 8500–8200 BC , but these were identified using
17423-426: Was domesticated. The main feature that distinguishes domestic einkorn from wild is that its ears do not shatter without pressure, making it dependent on humans for dispersal and reproduction. It also tends to have wider grains. Wild einkorn was collected at sites such as Tell Abu Hureyra ( c. 10,700–9000 BC ) and Mureybet ( c. 9800–9300 BC ), but the earliest archaeological evidence for
17556-477: Was grown on 220.7 million hectares or 545 million acres worldwide, more than any other food crop. World trade in wheat is greater than for all other crops combined. Global demand for wheat is increasing due to the unique viscoelastic and adhesive properties of gluten proteins, which facilitate the production of processed foods, whose consumption is increasing as a result of the worldwide industrialization process and westernization of diets . Wheat became
17689-584: Was historically a high status food, but during the nineteenth century it became in Britain an item of mass consumption, displacing oats , barley and rye from diets in the North of the country. It became "a sign of a high degree of culture". After 1860, the enormous expansion of wheat production in the United States flooded the world market, lowering prices by 40%, and (along with the expansion of potato growing) made
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