synonymCorn(Gramineae maize) generally refers to maize (Gramineae maize)
Maize (scientific name:Zea mays50. ) is a plant of the family Gramineae and the genus Maize, commonly known as corn.[1]GM corn: sweet and crisp.[31]Maize is a tall annual herb.Culms erect, usually unbranched, 1-4 m tall.Leaf sheath with transverse veins;Ligule membranous, about 2 mm long;The blade is flat and wide.The terminal male panicle is large, and the male spikelets are twin, up to 1 cm long.Caryopsis globose or oblate, usually 5-10 mm long.The flowering and fruiting period is autumn.[6]
Maize is native to Central and South America.[1]It is widely planted in tropical and temperate regions all over the world.[6]It is an excellent food crop with high nutritional value;It is also one of the indispensable raw materials for food, health care, light industry, chemical industry, etc.[3]In August 2018, the Ministry of Finance, the Ministry of Agriculture and Rural Affairs and the China Banking and Insurance Regulatory Commission issued a notice to include maize crop seed production in the central government's agricultural insurance premium subsidy catalogue.[29]
When Columbus arrived in the New World in November 1492, corn only existed in America.At that time, corn was the most important food crop for Indians. Without corn, there would be no Indian civilization.Through the selection of farmers and the work of breeders in modern times, maize has acquired more high-yielding traits and become one of the most important feed crops and food crops in the world.[25]
Any wild seed plant has its own seed dispersal method, so that its descendants can continue.Modern maize is a highly domesticated crop, and its continuation depends entirely on human beings.The ear of maize is a kind of distorted type in biology. It can produce a large number of seeds, but it does not have the method to spread its seeds.If the ear dropped on the ground under natural conditions is allowed to germinate and grow under conditions conducive to germination, it will produce a cluster of excessively dense seedlings. They compete for soil moisture and nutrition in a limited space, so that all of them cannot develop and bear fruit normally.Therefore, without human intervention, modern maize will be extinct within a few generations.They can be preserved only after being harvested, threshed and sown by people.Corn ears are created by human beings through long-term selection and breeding for their own needs. All wild plants and other plants do not have such ears.But corn must have evolved from some wild plant.[25]
Some studies believe that maize originated fromAmazonWatershed, such as Peru, Brazil, Bolivia, etc.However, some people believe that Mexico, Guatemala, Honduras, etc. in Central America are also the origin of maize.Among them, the "big ruminant grass" found in Mexico is said by some studies to be the ancestor of various maize types.In modern times, archaeologists have found corn ears and other evidence from ancient tombs and ruins in Mexico, Peru, Colombia, Brazil, etc. in South America, which is estimated to be 7000 to 5000 years old.Among them, there are sculptures of Indians worshipping maize.[12]
origin
From the viewpoint of biological evolution, this paper discusses the close ancestors of maize and the process of its evolution into modern maize.The wild ancestor of cultivated maize is a kind of maize.[25]
Maize nationality（Maydae）There are 7 genera of plants in the plant, including maize（zea）And Rubus（Tripsacum）Native to America.It is related to maize, which is similar to maize（Teosinte）, commonly known as big ruminant grass, originally classified as the genus Mizuo（Euchlaena）, changed toZea mexicana。It includes six annual wild species families, which are distributed in Mexico, Guatemala and Honduras. It has a low genetic relationship with maize, and is similar to maize in plant shape and inflorescence organs.[25]
From the perspective of ecological habits, like maize, it is an annual thermophilic plant with 12-13 hours of short sunshine.As a wild grass, it is distributed in the same area where maize was first domesticated in central Mexico.While most species of friction grass are perennial weeds with dense rhizomes, which is a trait never seen in maize cultivation.Cytological observation showed that the number of gametic chromosomes of Mexican maize like and cultivated maize was the same, with n=10, and the corresponding number of rubella was n=18.In the microspore mother cells of modern cultivated maize and Mexican maize like maize, the staining knots on pachytene chromosomes are often distributed near the middle of chromosomes;On the corresponding chromosomes of Rubus sativus and Guatemalan maize, apical knots were dominant, indicating that the chromosome characteristics were significantly different from those of maize.It is easier to cross maize like maize with cultivated maize by manual method. In the first generation of its hybrid, the corresponding chromosomes of both parents can be linked into pairs, showing homology, leading to good fruit setting.[25]
After maize like maize was gradually domesticated into cultivated maize in Central America, hybridization often occurred among different maize clusters, resulting in various variation types.The highest yield horsetooth maize distributed in the maize belt of the Midwest of the United States is the product of hybridization and selection between northern hard grain maize and southern typical deep horsetooth maize.[12]
taxonomy
Related species of maize: maize in taxonomy（Zea mays50. ) belongs to the family Gramineae, the family Maydeae, the genus Maize（zeaL.）。The Maize family consists of 7 genera, of which 2 are Maize and Mopyrum（Tfipsacum50. ) originated in the Western Hemisphere.Another 5 genera Coix（CoiscL.）、Tassel（Chionachne R.Br.）、Scleroderma（SchlerachneR.Br.）、Trifidum（TrilobachneHenr.) and Panicum（PolytocaR. Br.) originated in the Eastern Hemisphere.[25]
Theoretical hypothesis
There are five main theoretical hypotheses and several secondary theoretical hypotheses about the origin of maize.[25]
Theory of maize with lemma
The theory of maize with lemma was put forward by Saint Hi laire, a French naturalist, in 1829.At that time, someone sent him a unique type of maize from Brazil. This type of grain was wrapped in glumes, and he described it as a new varietyZea maysvar.tunicataIt is believed that this type is the natural state of maize, and it is speculated that its origin is in South America, possibly Paraguay.The theory of maize with lemma attracted the attention of scientists at that time. Because there is only one single gene difference between the lemma type and the normal maize, it is morphologically similar to the malformed maize types such as comgrass and teopod, but it does not have the characteristics of wild grasses and cannot exist in the wild,Many people are against this theory (Mange lsdorf, 1974).[25]
Common ancestor theory
In 1906, Montgomery first proposed that maize and big ruminant originated from a common ancestor.In 1918, Wei therwgx believed that it was not only maize and big ruminant grass, but also friction grass. These three plants were passed down from a common ancestor according to the usual evolutionary pattern described by Darwin.These three plants all have many undeveloped structures, which are traces of organs lost during evolution. If these structures can be fully developed, these three plants will have a common form in morphology (Mangelsdorf, 1974).[25]
"Three component" theory
This theory was put forward by Reeves and MangelsdorI in 1939. It consists of three independent parts.Maize with lemma may be an ancestor type;Since maize with lemma is a common feature of wild gramineous plants, Reeves and Mangelsdorf believe that the strange character of "lemma" is the result of a single wild gene imprinted on a highly domesticated modern maize variety.The third part of this theory is that during the domestication of maize, the big ruminant grass played at least a very important role in the evolution of maize.In some areas of Mexico, there is a common growth of big ruminant grass around maize fields. It frequently crosses with maize, and its hybrid is highly fertile, and it is easy to cross with one or two parents for many times. As a result, there is inevitably a gene flow from big ruminant grass to maize.Therefore, many modern maize varieties must be the product of hybridization with big ruminant grass in the past.[25]
Hybrid theory of wild maize and perennial big ruminant grass
When it was reported in 1979 that diploid perennial big ruminant grass (i.e. diploid perennial maize) was found, Mangelsdorf put forward another theoretical hypothesis that maize originated from the hybrid of wild maize and perennial big ruminant grass.He believed that the ancestors of modern maize were not one, but two. It originated from the hybrid offspring between the original lemma - popcorn and the diploid perennial big ruminant grass.This hybrid not only produces modern maize, but also produces annual big ruminant grass.The idea of this theory was originally put forward by Wiucers, and Mangelsdorf tested this hypothesis with hybridization experiments in early 1979.The hybrid parents used were the original maize variety Palom ero Toluqueno and the diploid perennial big ruminant grass, the hybrid generation I crossed each other and backcrossed with the perennial big ruminant grass.Four plant types were obtained from F2 population: annual big ruminant, perennial big ruminant, annual maize and perennial maize, and a considerable number of annual big ruminant plants were found in backcross population (Mangelsdorf, 1986).[25]
From supporting the theory of maize with lemma to proposing the theory of hybrid between wild maize and perennial maize, Mangelsdorf has always insisted on the opinion that there are extinct ancestors of wild maize, which is mainly based on archaeological discoveries.Since the late 1940s, a large number of maize cobs or fossil pollen and fragments of large ruminant grass have been found in at least 10 regions from Arizona to Peten in Guatemala (MacNeish, 1985).These maize specimens range in age from about 8000 BC to A.D.The most abundant and valuable archaeological specimens are from TehuaIn the Call Valley, the caves excavated there are the holes where the ancient people accumulated garbage. The corn cob in the holes shows an obvious sequence of evolution due to domestication in different levels.20364 maize cobs or cob parts and 3822 maize fragments were found there.Among them, 75 maize cobs came from the earliest cultivation period - the Coxtadan period, about 5000 BC to 3500 BC.These cobs are small, about 2.5 cm long, with soft and long glumes, shallow, long but not wide shell, as obvious as the big straw shell;Most cobs bear 8 rows of grains, with the remains of male spikes at the top, and each spike has about 5060 grains.The next period is the Abeias period, about 3400 BC to 2300 BC.Most of the cobs (176 cobs) on the excavation plane from this period are very similar to those in the Coxtatlan period, but there are 10 cobs that are obviously different. Among them, 8 inflorescence axes and glume tissues are hardened, and the glumes are low, thick and curved. They are larger than other cobs. There are 2 large cobs that have some characteristics of big ruminant grass and also have more rows.These 10 panicles seemed to be the first to show the characteristics determined by the dominant genetic characteristics of ruminant grass.In the excavations of the Ajalpan period in about 1000 BC, there were a considerable number of cobs with this feature, and 104 of 186 cobs had this feature (MacNeish, 1985; Beadle, 1980). A cob with the age of 4000 BC had an abscission layer similar to that of ruminant grass extending halfway across the inflorescence axis.The total effect of gradual infiltration of ruminant grass is similar to that of P1 hybrid of modern ConfiteMo rocho maize and Guerrero ruminant grass (Gali. nat, 1977).In the specimens from the Coxtatlan cave in Tehuacan Valley, one of the six complete cobs from the 13th layer and three of the six complete cobs from the 11th layer are slightly larger in volume. Mangelsdorf et al speculated that they were "the first products of cultivation" (Mangelsdorf et al., l967).[25]
The evidence of fossil pollen supporting the idea that there was a wild maize ancestor came from the core retrieved 70 meters deep from the borehole at BellasArtes, Mexico City, where 14 pollen grains were found.At that time, it was estimated that these pollen grains existed for 25000 to 80000 years from 2011.Among them, 9 grains are smaller and 5 grains are larger. The size of these 5 grains is within the range of maize pollen grains. Barghoom identified them as maize pollen grains. According to this discovery, the existence of maize was pushed back to 80000 years ago (Beadie, 1981; Sears, 1984).Maize pollen was found in various sections of GurlaNaquitz cave from 8000 BC to 2011 (Schoenwetter, 1974).According to Ma cNeish, the maize pollen before 5000 BC here is wild maize, and there is no maize residue in the plant residues of all layers from 8000 BC to 5000 BC.Since maize was discovered in archaeology in all places earlier than the discovery of ruminant grass, and maize was found not affected by the gradual infiltration of ruminant grass earlier than the discovery of maize affected by the gradual infiltration of ruminant grass (MaeNeil, 1985), Mangelsdorf and his colleagues believe that ruminant grass is of modern origin, and it cannot be the ancestor of maize.[25]
The age of BellasArtes' fossil pollen has recently been questioned.The drilling site where the core was taken out used to be a shallow lake and marsh. The core section has three layers, the top layer is 6-8 meters thick, and the mixture of Compositae, Amaranthus and Gramineae plants (including maize) is deposited;The middle layer, about 50 meters thick, is the magma erupted by the Xitle volcano;Below the 71.2m level, the sediment is still the same as the top layer.Due to the deposition of lava and volcanic ash, the ground here subsides at a rate of 4 cm per year, and will subside by 70 m around 2000.Therefore, these fossil pollen is not 80000 years ago, but about 2000 BC maize pollen (Sears, l984).[25]
1964 RS. McNish found some well preserved wild corn cobs in the caves where prehistoric humans lived in the Tewakan Valley in southern Mexico. It is estimated that there were remnants of the corn seed burst in 5000 BC, and the modern cultivated species evolved from this.However, some people believe that maize evolved from wild Mexican maize (Euchl aenamexicana), or was formed by crossing maize like maize with other gramineous plants.[25]
Introduced into China
On the introduction of maize varieties into China《Corn Varieties of China》Chinese said: "Maize was introduced into China from Europe in the first half of the 16th century, and it was introduced into China in Mingtian Yiheng《Stay in Green Rizhao》And Li Shizhen《Compendium of Materia Medica》It is recorded in both. "According to Japanese Singkawa Qingqin, the Portuguese introduced maize to India in the early 16th century, and then from India to China.However, recent discoveries indicate that maize was introduced into China earlier than the Ming Dynasty.Here are some examples: Jia Ming of Yuan Dynasty, "Food Instructions - Grain", Volume II: "Maize is wheat, sweet and flat in taste." Li Dongyuan, Yuan Dynasty, "Food Materia Medica - Grain", Volume V: "Maize: a kind of corn sorghum, which is planted in western soil. Its seedling leaves are all like maize, fat and short, and also like coix. The seedling is three or four feet higher, and flowers and ears in June and July, like chaff.A bract appears in the axil of the seedling, like a brown fish, with white whiskers hanging from the bract.After a long time, the buds will come out and gather in clusters.The seeds are as big as rice dumplings, and can be fried. "[12]
There is no clear conclusion about the true time and way of the first introduction of maize into China, but according to the preliminary study of Chinese agricultural heritage, maize was introduced into China at least before 1511 AD.Maize has been recorded in the ancient book Yingzhou Annals in 1511 AD.There may be two routes to China: one is from India to Sichuan via Tibet, and the other is from sea to southeast coastal areas and then to inland provinces.The maize introduced in the early stage was hard grain type, while the horse tooth type was introduced after the 1920s.In 1927, "Meirenhuang" and "White Crane" were introduced from the United States at Gongzhuling Agricultural Experimental Farm;In 1930, Mingxian School in Taigu, Shanxi, introduced the "Golden Queen" from the United States;In 1931, "Italian white" was introduced, and after selection, "white horse tooth" was formed;In 1943, the "British particle" was introduced from Europe.In the early 1950s, the "Golden Queen" and "White Horse Teeth" varieties were popularized in a certain area in the north.After long-term cultivation and selection under local conditions, these introduced horse tooth type varieties differentiated into varieties suitable for local conditions, and new varieties with intermediate grain types were produced through introgression hybridization with local hard grain type varieties.Before 1760, waxy varieties were formed by mutation and selection of local varieties of hard grain type in Yunnan and Guangxi, which are the origin center of waxy maize.Cao Zhenbei and Xu Wenwei divided Chinese maize varieties into five "races" and four groups that may be independent races.[25]
morphological character
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Maize
Annual tallherbaceous。Culms erect, usually unbranched, 1-4 m high, with aerial prop roots at each node of the base.Leaf sheath with transverse veins;LiguleMembranous, about 2 mm long;bladeIt is flat and broad, linear and lanceolate, the base is round and ear shaped, hairless or with defective soft hair, the midrib is thick, and the edge is slightly rough.The terminal male panicle is large, and its main axis isracemeBoth the axis and its axilla are covered with fine pubescence;malespikeletTwins, up to 1 cm long, spikelet stalks one long and one short, 1-2 mm and 2-4 mm long respectively, puberulent;The two glumes are nearly equal, membranous, with about 10 veins, ciliated;Lemma and palea hyaline membranous, slightly shorter than glume;antherOrange yellow;It is about 5 mm long.Female inflorescence is enclosed by most broad sheathed bracts;Female spikelets are twin, arranged in 16-30 longitudinal rows on the stout ordinal axis, with two glumes of equal length, broad, veinless, ciliate;LemmaandPaleaTransparent membranous, pistil with extremely long and thin linearstyle。CaryopsisSpherical or oblate, exposed when matureglumeandLemmaIn addition, its size varies with different growth conditions, generally 5-10 mm long, slightly longer than its length, and its embryo length is 1/2-2/3 of the caryopsis.Chromosome 2n=20,40,80.[6]
The physical characters of seeds are composed of grain color, grain shape, seed coat luster, grain length, grain width, 100 grain weight, grain diameter, grain uniformity and hard seed rate.The color of maize grain includes three parts: seed coat, aleurone layer (rich in protein, also known as protein layer) and endosperm.In most cases, the color of the mature kernel endosperm of maize is yellow or white,seed coatandAleurone layerNo color, transparent.According to the color of maize grains, there are three kinds of maize: yellow maize, white maize and mixed maize.According to the grain shape, hardness and different uses of maize, maize is divided into ordinary maize (hard grain type, middle type, horse tooth type, hard to horse type, horse to hard type) and special maize (high lysine maize, high oil maize, sweet maize, popcorn, waxy maize).The shape and size of seeds vary with varieties. Generally, maize is 8-12 mm long, 7-10 mm wide and 3-7 mm thick. If the difference between maize grains is too large, it will be difficult to clean and break maize during processing.[3]
There are many varieties of maize. According to the use, there are grain feed varieties, vegetable varieties (including waxy, sweet, and corn shoot types), processing varieties (sweet corn, corn shoot types), and explosive grain varieties (popcorn special varieties).[2]
Maize likes light and does not tolerate shade. It is a short day plant.Maize likes temperature. The suitable temperature for growth is 22-30 ℃, the temperature for seed germination is 6-10 ℃, the temperature for jointing is 15-27 ℃, the temperature for flowering is 25-26 ℃, and the temperature for filling is 20-24 ℃.[16]
temperature
Maize is a warm crop, which requires higher temperature during the whole growth period.The biological effective temperature of maize is 10 ℃.Seed germination requires 6-10 ℃, slow germination below 10 ℃, vigorous germination at 16-21 ℃, the optimal temperature for germination is 28-35 ℃, and stop germination above 40 ℃.Seedling stage can withstand short-term low temperature of - 2 to 3 ℃.The jointing stage is 15-27 ℃, the flowering stage is 25-26 ℃, and the grouting stage is 20-24 ℃.Different maize varieties have different requirements for temperature. The accumulated temperature of early maturing varieties in China is 2000-2200 ℃;Medium maturity varieties 2300-2600 ℃;Late ripening and 2500-2800 (3000) ℃.Most of the world's corn producing areas are concentrated in July, where the isotherm is 21-27 ℃ and the frost free period is 120-180 days.Maize is a plant with short sunshine, which can blossom and bear fruit under short sunshine (8-10 hours).[26]
illumination
Spectral components have a great impact on the development of maize. According to research, maize develops quickly under blue and other short wave light in the daytime, while develops quickly under red and equal long wave light in the morning or evening.Corn isC4 plantsIt has strong photosynthetic capacity and high light saturation point. Generally, the photosynthetic intensity of corn is 35-80 mgCO2/Dm2 · leaf · hour.The plant of corn is tall and the leaf area is large, so it needs more water.[26]
water content
The optimum precipitation during maize growth is 410-640mm. Drought affects the yield and quality of maize.It is generally believed that areas less than 150 mm in summer are not suitable for planting corn, while excessive rainfall will affect light, increase disease, lodging and weed damage, and also affect the improvement of corn yield and quality.Although corn needs more water, its relative water demand is not too high. Its transpiration coefficient is 240-370, which is higher than that of barley (280-400), oats (340-500)Purple flowerAlfalfa (831) and clover (797) are low and water consumption is economical.Maize has a strong root system, which can fully utilize the water in the soil.When the temperature is high and the air is dry, the leaves curl upward to reduce the transpiration area, so that the water absorption and transpiration are properly balanced.[26]
soil
Corn is not very strict with soil.The loose, deep and organic rich chernozem, chestnut soil and sandy loam can be used to grow corn in the range of 6-8.Maize can grow at seedling stageNaCl0.21% soil, more than plant death.Corn plant contains 16 elements, exceptC、H2O2From COtwo。Both should be absorbed from the soil.N, P, K, S, Ca and Mg are in large demand, while Fe, Mn, Zn, Cu, Ba and Cl are in small demandtwo。Etc.From 10 days before tasseling to 25-30 days after tasseling, maize has the fastest material accumulation and the most fertilizer absorption. This stage absorbs 70-75% of N, 60-70% of P and 65% of K in the total amount of fertilizer absorption.It is necessary to produce 100 jin corn grainsNI75-2.22kg, HtwoPOfour0.59-0.85 kg andK2O1.5-1.84kg.The ratio of the three elements is 2.6:1:2.[26]
Distribution range
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It is native to Central and South America.[1]whole worldtropicandthe temperate zoneWidely planted in the region, mainly distributed between 30 ° - 50 ° latitudes.The largest cultivated areas are the United States, China, Brazil, Mexico, South Africa, India and Romania.It is cultivated in all parts of China, and the main production areas are the northeast, north and southwest mountain areas.[6][26]
Growth habit
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The flowering and fruiting period is autumn.[6]Compared with traditional grain crops such as rice and wheat, maize has strong drought tolerance, cold tolerance, barren tolerance and better environmental adaptability.[3]
Full growth period
The whole life of maize is from sowing to new grain maturity.Generally, the number of days from sowing to maturity of maize is called the whole growth period, and the number of days from emergence to maturity is called the growth period. The length of growth period and yield are related to factors such as variety characteristics and environmental conditions.[24]
The active accumulated temperature required by a variety during the whole growth period (the sum of the daily average temperature ≥ 10 ℃ during the growth period) is basically stable. The growth period will be appropriately shortened under higher temperature conditions, while the growth period will be appropriately extended under lower temperature conditions.In production, it is generally divided into five categories: early maturity, medium early maturity, medium late maturity and late maturity.[24]
Corn monoculture and spring sowing are the main planting methods in dryland corn area. Due to the vast land, the ecological conditions change significantly.The frost free period increases from north to south. The frost free period in the main corn planting areas is 130-180 days. The active accumulated temperature increases from north to south, with an average of about 3100 ℃;The growth period of spring maize varies greatly, generally between 100-135 days.[24]
Childbearing period
During the whole life of maize, the external morphology, internal physiology and metabolism will undergo periodic changes, which are called the growth period.When more than 50% of the plants show the characteristics of a certain growth period, the whole field enters the growth period.[24]
cultivation techniques
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Seed selection
To achieve high yield of maize, maize seed selection is the key.When selecting seeds, we must adjust measures to local conditions and combine with local actual planting conditions to select excellent varieties suitable for local soil texture, climate and cultivation level. It is best to select new hybrid varieties with high yield potential.It is required that the budding rate and budding potential reach the standard, and the budding rate must reach more than 85%.The maize varieties suitable for cultivation in Zhangjiakou area include Huanong 866, Wannuo, Liaodan 565, etc.[10]
Parcel Selection
Maize needs to absorb a lot of water and nutrients from the soil during its growth. Due to its developed roots, it does not have high requirements for soil conditions and has strong adaptability to the environment.Generally, the plot with flat terrain, deep soil layer, loose texture, good permeability, medium fertility and better water and fertility conservation is selected for planting maize.[10]
begin sowing in good time
Land preparation, ploughing and moisture generation shall be carried out on the land, and timely sowing shall be carried out on the basis of sufficient base fertilizer.As it is located in cold and cold areas, it is necessary to sow early, and it can be considered to promote the use of plastic film planting.The use of plastic film can not only sow early, extend the growth period of maize, but also play a role inMoisture preservation, warming, weeding, and the use of plastic film can also promote the growth and early maturity of maize, and can change varieties with long growth period and high yield potential, so as to achieve the yield increase and efficiency of maize.[10]
Reasonable close planting
To increase the yield of maize, we can reasonably increase the planting density.This planting method is generally preferred in areas with good soil fertility and irrigation conditions.The planting density is generally 3000-3500 plants per mu, and the planting density of density tolerant varieties is larger, which can reach 4500-5000 plants per mu.Different planting methods lead to different densities.The mechanical sowing line spacing is generally 60-70cm, and the manual sowing line spacing is mostly 50-60cm. Large and small ridges or wide and narrow rows can also be used for planting.Increasing planting density is an effective measure to increase yield, but it is required to select varieties with good density tolerance, and at the same time, it is necessary to increase fertilizer and apply balanced formula fertilizer accordingly.[10]
Water and fertilizer management
High yield water and fertilizer management of maize is the key.Maize needs different water and fertilizer in different growth periods. Fertilization and watering shall be carried out strictly according to the growth characteristics and biological requirements of maize crops, and fertilization shall be reasonable to balance nutrition.Therefore, fertilizer and water should be arranged according to the characteristics of maize.[10]
Characteristics of water and fertilizer demand in different periods
one
Sowing seedling stage: the amount of fertilizer and water required is very small, but it is very critical and important. There should be sufficient and appropriate soil moisture to ensure the whole seedling.[10]
two
Emergence jointing stage: maize requires little fertilizer and water at this stage, and proper drought is conducive to squatting.[10]
three
Jointing stage big bell mouth stage: during this period, the water demand for fertilizer increases, and the nutrients and water should be properly increased to ensure the growth demand of maize.[10]
four
Big bell mouth stage filling peak period: about one month, this period is the period with the largest amount of fertilizer and water demand, especially before and after the silking period, which is very sensitive. At this time, lack of fertilizer and water will lead to malnutrition, weak growth, difficulty in male pollination, and serious yield reduction.[10]
Fertilization technology
Fertilization amount of maize: 1000-1500 kg of farmyard manure, 5 kg of phosphate fertilizer, 40 kg of urea and 10 kg of potassium fertilizer per mu.The fertilization principle of maize is to apply sufficient base fertilizer, early seedling fertilizer and heavy topdressing.1/4 of nitrogen fertilizer and all farm manure, phosphorus fertilizer and potassium fertilizer are used as base fertilizer at one time, and 3/4 of nitrogen fertilizer is used as topdressing before jointing.Generally, seedling fertilizer is applied 30-35 days after sowing, leaves are 6-7 leaves, jointing fertilizer is applied 60-65 days after sowing, leaves are 11-12 leaves.[10]
Field management
The field management of maize is mainly seedling management.Seedling management mainly includes seedling inspection, seedling supplement, seedling thinning and seedling fixation.After the emergence of maize seedlings, it is necessary to check and replenish the seedlings in time to prevent the seedlings from crowding each other, competing for water and fertilizer, and wasting nutrients and water.Generally, maize seedlings grow to 3-4 leaves and settle at 6-7 leaves.Intermittent and fixed seedlings are the key link to determine the density. Generally, sparse, small and large seedlings should be kept, and healthy seedlings should be kept.If thinning and seeding are completed at one time, they can be carried out in the 4-5 leaf stage.The plant spacing can be determined according to the density index and row spacing. In addition, 20% more seedlings should be reserved for loss.[10]
Timely harvest
Timely harvesting can ensure the quality of maize.Timely harvest according to local climate characteristics and crop growth period.Fresh maize should be harvested when the grain is full, after filling, and when the taste is best, generally 22-24 days after pollination, and should be sold or processed in time after harvest.The harvested maize can be harvested when it reaches physiological maturity. After harvest, it should be peeled, dried and dehydrated in time for storage.[10]
Disease and insect control
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disease
The main diseases of maize includeCercospora leaf spot, large and small shift diseasesrust、Stem rotIt is necessary to use methyl thiophanate, carbendazim or triadimefon spray in time for prevention and treatment.[10]When the pathogen appears, there will be obvious harm on the maize plant.Therefore, planting personnel should pay attention to the plant growth status, and pay attention to the changes in the process of corn growth in a timely manner.Disease not only affects plant growth, but also has certain infectivity.Pesticide application plays an important role in disease control.However, excessive use of pesticides will cause harm to plant growth and later human consumption.Therefore, when applying pesticides, it is necessary to know the amount of pesticides in advance.[11]
In case of frequent rain and fog and low temperature at the ear stage of maize, it will usually cause a large area outbreak of small spot disease, sheath blight and other diseases.Take sheath blight as an example, the main parts of the disease are in the ear and leaf sheath, and may also appear on the stem. After the disease, light brown patches appear on the leaves.As time went on, the disease became worse, and the disease began to spread from the basal leaf sheath to the upper part of the plant, and finally developed to the ear, making the ear bracts appear large and cloudy spots.Foliar spray control is usually carried out by mixing 37.5ml/ha of Flusilazole with 2250l/ha of water.During the filling and maturity period, the main diseases are premature senescence and bacterial wilt. Generally, improved varieties with strong resistance to disease are used to strengthen field management to ensure the transparency and ventilation of maize population.To prevent and control small spot disease, 50% carbendazim or 70% thiophanate methyl wettable powder 500 times liquid can be sprayed every 7-10 days.[11]
Insect pest
Corn pests mainly includeCorn borerandaphidWait, use it in timeImidacloprid, cypermethrin, etc.The prevention and control of maize diseases and pests should focus on prevention, supplemented by treatment.Targeted prevention and control of diseases and pests shall be carried out to achieve early prevention and treatment.Seed dressing with chemicals and maize seed coating can be carried out, which can not only prevent diseases and pests, but also promote the healthy growth of maize seedlings.[10]
Key values
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nutritive value
The vitamin content of maize is very high, 5-10 times that of rice and wheat. Among all staple foods, maize has the highest nutritional value and health care function.Contained in maizeriboflavinIsotrophic substances are very beneficial to human body.[2]
It is worth noting that the nutritional value of special maize is higher than that of ordinary maize, and the moisture, active substances, vitamins and other nutrients of fresh maize are much higher than that of old maize.[2]
Medicinal value
According to《Compendium of Materia Medica》Record: Maize was planted in the west. It is non-toxic and can regulate the middle and appetizers.The pollen and embryo of maize also contain a large amount of vitamin E and maize flavonoids. Regular consumption of maize products can delay human aging and enhance human physical strength and endurance.Maize fructose syrup can prevent gingival bleeding and has an auxiliary effect on the treatment of cardiovascular diseases.Applying maize modified starch to the burned part of human body can avoid scar formation.Maize starch is also a good medium for penicillin production.It is made of oxidized maize dextrosesorbitolPaste can be used to prepare ascorbic acid tablets.Corn also has the function of beauty and slimming.Compared with soybean and wheat, maize has lower fat and protein content and higher carbohydrate content.[3]
Maize whiskers
Corn whisker
Maize whisker, also known as "dragon whisker", has a wide range of prevention and health care purposes, so it has the saying that "one corn whisker can be called two gold coins".[7]
Maize whiskers contain crude fiber, crude protein, polysaccharide and crude fat.The chemical composition of maize whiskers has changed greatly in different varieties and different periods.The content of total phenols and total anthocyanidins in maize fiber reached the highest at milk ripening stage, and the content of total flavonoids and antioxidant activity were the highest at silking stage, but the content of total phenols and total flavonoids in sweet maize and white maize were the highest at silking stage.[1]
The research shows that the water extract of maize whisker can reduce thecalcium oxalateVolume of crystallization;The flavonoid extract from maize whisker can significantly reduce the degree of joint swelling in gouty arthritis model rats, and has anti gout effect.[1]
By inhibitingAlpha amylaseandα - glucosidaseInhibiting glucose intake to control postprandial hyperglycemia is considered to be an effective method to treat T2DM and related complications.Maize whisker extract rich in phenols and flavonoids is often reported asAlpha amylaseAnd α - glucosidase inhibitors.The ethyl acetate extract of maize silk can significantly reduce the level of reactive oxygen species induced by hydrogen peroxide or methoxyglycolaldehyde, reduce the activity of rat pancreatic β cells, inhibit cell proliferation, and improve the insulin, glucokinase, and pancreatic duodenal homeobox-1mRNAExpression, enhancing glucose stimulationinsulinSecretion to regulate blood sugar.[1]
Among the main components of maize husk, dietary fiber accounts for the highest content.However, due to the rough taste and poor water solubility of maize husk, it is not popular with the public, and the dietary fiber component is not fully utilized, leading to waste.Maize dietary fiber can reduce blood fat, blood pressure and the possibility of intestinal diseases.[1]
ecological value
Corn straw
Corn stalk
Straw crushing and returning to the field can slowly decompose and release mineral nutrients in the soil through the role of microorganisms in the soil, which can be absorbed and utilized by crops. The organic matter and humus formed in the decomposition process can provide raw materials for microorganisms and soil organisms in the soil, thus effectively improving the soil structure and improving soil fertility.The by-product excrement produced from the processing of maize straw as feed is a good agricultural raw material.The direct use of straw resources to produce biogas can effectively alleviate the problem of rural energy shortage.After maize straw is crushed, phosphate fertilizer, ammonia fertilizer, lime and water are added in a certain proportion for fermentation.Bagging of fermented clinker can be used to produce edible fungi, such aslawyer's wig、MushroomThe biotransformation rate can reach 70-100%, and the waste can be used asFarmyard manure。The new type of corn straw beverage has bright color, special aroma of straw, sweet and sour taste, and good taste and even texture.[1]
Feeding value
Maize straw as livestock feed is one of the most efficient utilization methods of straw, and can bring certain economic benefits.[1]Maize is rich in nutrition in seeds and stems, and is a high-quality feed for various livestock.Every 1kg of pork needs 5.6kg of corn grain, and 1kg of beef needs 10kg.100 kg maize grain is equivalent to 135 kg oats, 125 kg sorghum and 130 kg barley.It is an indispensable feed for beef cattle, cows, horses, sheep, pigs, poultry and fish.The whole plant of maize can be fed, with the utilization rate of more than 85%. It is the famous "king of feed".Corn has 5-10% crude protein content, less cellulose and good palatability;All kinds of livestock like to eat.LysineTryptophanThe content of lysine and methionine is insufficient, generally containing 0.2-0.5% lysine, and some varieties bred abroad reach as high as 5%.Maize contains different amino acid components in different parts, and the grain is the most abundant.Corn is also rich in trace elements.According to the determination, maize seeds contain 906.72mg/kg vitamin A, 0.934mg/kg vitamin B1, 0.272mg/kg vitamin B2, 5.073mg/kg vitamin E, 1.3-2 mg/kg carotene and 3.7-6.3 mg/kg riboflavin.According to Beijing Agricultural University.The organic matter digestibility of maize is high.Maize is used as feed in 85% of developed countries, and its grain is the concentrate of pigs, chickens, cows and beef cattle.Mowing and silage maize are essential feedstuffs for cows.With the development of production, maize has become increasingly important as a feed crop in China.[26]
The kernel of maize consists of epidermis, endosperm, embryo and root cap.According to its structural characteristics, its deep processing can be divided into dry processing and wet processing.Dry milling refers to dry milling of maize, which is mainly used in various food, feed and fermentation industries.Wet processing is to use physical methods to divide maize grains into five products, namely maize pulp, maize starch, maize germ, maize gluten protein and cortical fiber. Among them, maize starch is the main product, which can be directly eaten or reprocessed. All these products are widely used in food, textile, paper making, chemical industry, medicine, building materials and other industries.[8]
one
The main characteristics of maize starch are as follows: the amylose content is high, up to 28%;High gelatinization temperature (62-72 ℃), with good shear resistance;Dense particles;There are many lipid compounds, which are easy to form amylose lipid compounds.Starch accounts for about 70% of the dry weight of maize grains and is an important part of maize grains.Starch can be converted into low molecular compounds or high molecular polymers by physical and chemical methods, which can be used as good processing materials.The extraction technology of maize starch mainly includes two processing methods: dry method and wet method.Compared with the dry method, the wet method is the main processing method used for corn processing because its processed products are more pure, the by-products are easier to recover, the operability is strong, and it can better meet the market needs and facilitate deep processing.[3]
two
Maize protein powder: Maize protein mainly exists in two forms: maize gliadin and maize glutenin, both of which are water insoluble proteins.Corn gliadin has good wettability, cohesiveness, water holding capacity and film-forming property, which can be used as the coating of tablets to hide the smell of the tablets themselves, and can also double the hardness of the tablets. Besides, it has moisture-proof, anti-static, fresh-keeping, antioxidant and certain bacteriostatic functions, making it have good development potential in the food, drug and biodegradation industries.[3]
three
Corn germ oil: corn germ oil, also known as corn oil, is made from corn oil through deacidification, degumming, dephosphorization, decolorization, dewaxing and deodorization.Every 100 kg of maize contains 8-10 kg of germ, and every 100 kg of pure germ contains 35-40 kg of oil, twice the oil content of soybean.Generally, corn oil is golden yellow, transparent, and has the smell of fresh corn.With peanuts, rapeseed andsunflower oilCompared with corn oil, it has higher nutritional value. Its protein, mineralslecithin, vitamin A, D, E, etc. are very rich, and also contain 30% oleic acid, 57%linoleic acidIt has significant effects on infant growth, prevention and treatment of cardiovascular and cerebrovascular diseases, anti-aging, etcNight blindness、XerophthalmiaAnd treatmentbronchiectasia, dermatitis, etc. have good effects. The latest research shows that maizeGerm oilIt also has a certain anti-cancer effect.[3]
four
Corn starch sugar production: there are 24 sugar products made from starch in China, such asxylitol、MaltodextrinMaltose maltose, liquid glucose, etc., especially the high sweetness of xylose, will not causedental caries, is widely used in the production of chewing gum, candy, drinks, etc.Crystalline glucose, an important product of starch sugar, has gradually developed in the chemical industry, fermentation, food, medicine and other industries with the development of starch sugar.With the research of biological hydrolysis technology, the technical transformation from enzyme acid method to double enzyme method has been completed.[3]
five
Corn starch brewing: according to the production practice, corn starch is suitable for brewing light beer and beer with high auxiliary materials. The taste difference between corn starch and beer produced by rice is not obvious, and the consumption is lower than that of rice.The fat and protein content of maize starch is very low. The use of maize starch can significantly extend the storage period of beer, reduce the color of beer, and improve the stability of beer smell.Zhang Ning et al. obtained the treated maize buds by germinating, removing the umbilicus and drying maize, and then further reduced the fat content of maize by using the hydrolytic enzyme system in the germination process of maize.Maize starch is highly soluble and can be completely transformed into soluble substances, so it can be used efficiently.[3]
six
Application in petrochemical industry: after adding ethanol with high combustion value, gasoline can burn more fully and reduce pollutantsCOandSO2To improve the atmospheric environment.As a renewable and clean energy, fuel ethanol uses maize (or other grains, sugars, etc.) as raw materials, and uses the principle of biological fermentation to produce fuel ethanol with a purity of more than 99.5%Anhydrous ethanolAnd mixing fuel ethanol and gasoline in proper proportion to produce ethanol gasoline.In addition to making fuel, maize can also be used to repair oil contaminated soil.Adding surfactants from different sources, such as chemical synthesis, microbial production and plant extraction, to the soil at a concentration of 10000 mg/L can enhance the remediation of petroleum hydrocarbons in the soil by maize.Through the test, it was found that after adding surfactants and soybean lecithin to the soil, the number of microorganisms increased significantly, and the reduction of petroleum hydrocarbons increased by 12% and 19% respectively. However, after adding chemical surfactants, the number of microorganisms and the accumulation of polycyclic aromatic hydrocarbons in maize plants did not change significantly.The technology is convenient and practical, and it is an environment-friendly treatment method, which can be widely used to control oil pollution to soil.[3]
seven
Research on modified starch: change some physical or chemical properties of starch, and the produced starch is calledDenatured starchorModified starch。The treatment process of modified starch is generally to cut off, oxidize, recombine starch molecules or introduce substituents to change the molecular structure of starch.According to the different treatment methods, the modified starch can be divided into physical modified starch, chemical modified starch, gene modified starch, enzyme modified starch and composite modified starch.With the continuous development of industrial technology, modified starch, with its unique physical and chemical properties (such as high viscosity, stable freeze-thaw properties of paste solution, etc.), has become a new important raw material in the fields of food, medical and health, paper making, textile, fine chemicals, construction, etc.In the food industry, modified starch can be used as a thickener to improve the quality of food;In the paper industry, as a binder, sizing agent and auxiliary agent, it can improve the printing performance and improve the quality characteristics of paper;In the textile industry, modified starch can be used to replace ethylene size, which is non-toxic and harmless to human body and will not pollute the ambient air.[3]
eight
Research on resistant starch: resistant starch has both the delicate taste of raw starch and the function of dietary fiber, and has special nutritional value and special physiological function. Therefore, resistant starch is a good food additive.MaizeResistant starchIt is developed by countries all over the world.[3]
There is a saying that European civilization is wheat civilization, Asia is rice civilization, and Latin America is maize civilization.Mexico and Central America are the birthplace of maize. According to archaeological findings, as early as 10000 years ago, there was wild maize here, and Indians have cultivated maize for 3500 years.Archaeologists have found the remains of the maize culture between 7000 BC and 1540 AD in the Tewakan Valley of Puebla State, which shows how the ancient Indians gradually began to pick wild fruits and transitioned to artificial cultivation of maize while hunting activities became scarce.[9]
The long history of maize culture makes Mexicans perfect their cultivation and processing technology of maize.In Mexico, there are not only white maize, yellow maize, but also dark blue maize, dark green maize, purplish red maize, as well as colorful maize arranged among red, blue, green, white and yellow.The variety of maize food made by Mexicans has been countless, and there are still new creations.[9]
Maize worship is one of the most important cultural phenomena in Mexico.yesMexicoAs far as people are concerned, maize is not just food, but a divine object, which has been worshipped in Indian religion for thousands of years.There are several maize gods in ancient Indian divinities, such as Sint Alter, Silonen, Comac Alter, and so on. They all symbolize happiness and luck.Mexican people have many myths and legends about maize, which link the origin of mankind with the discovery of maize.According to the legend of the Nawa Indians, in ancient times, the gods, mainly Kete Sarko Atel and Tez Katripoka, created the world and human beings in repeated struggles. When the fifth sun shone on the earth, human beings developed from eating trees, fruits and plants to eating maize.In Mayan mythology, the human body was made of maize by the creator.People still call indigenous people "corn people", the novels of Guatemalan writer and Nobel Prize winner Asturias《Maize Man》It is about the experience of Maya people in modern society.[9]
The history of Mexico keeps pace with the evolution of maize.SpainAfter the invasion of the People's Republic of China, it once spent huge financial resources to promote wheat planting in Mexico, providing preferential conditions in terms of land and funds, but the pattern of corn dominated crop planting in Mexico has never changed.The life of ancient Indians, even some Indians, was organized and arranged closely around the planting and harvesting of maize.Indian tribes and village communities all set maize mills in the center of villages and towns. Because every household needs to grind flour, the mill has become a social place of the whole village.Sometimes the villagers' assembly is also held here, which links it with "power".[9]
In the Mayan circular solar calendar, a year is divided into nine solar terms based on the position of the sun and the cultivation of maize.After one year's hard work, the most joyful and relaxing day for people is the second solar term called "maturity", which is equivalent to August 2. This is the time when maize begins to mature and people begin to enjoy tender maize.IndianAfter harvesting maize, religious ceremonies and festivities should be held around a large number of maize, such as sacrificing maize gods with lambs and drinks.Such festivities will last for a month until all maize is harvested.Even in other rural festivals, maize is also placed on the altar as an indispensable mascot. Sometimes people use colorful maize grains to form religious pictures or to make divination.[9]
In modern Mexican society, maize plays an important role in people's life.Mexico needs to plan a large area of land to grow maize, and each region will add other crops according to its own climate and soil characteristics. Specifically, at the rural grass-roots level, villages of different sizes will be formed according to the size of maize fields.The history of Mexican civilization has almost kept pace with the evolution and development of maize, which has deeply infiltrated into the organizational form of Mexican society, people's lifestyle and way of thinking.[9]
The source of inspiration for poets and artists.Ancient Indian poets wrote many poems extolling maize, some of which are popular.Poet in Mexico, winner of the 1990 Nobel Prize for LiteratureParsIn his poems, the image of maize has repeatedly appeared, such as the line in Between Stone and Flower: "You restrain, endure, live like a bird/from a handful of maize fried noodles to a jar of maize porridge." In Sun Stone, he sang with passion: "Your maize skirt is dancing and singing/Your crystal skirt, water skirt...".[9]
The image of maize and maize god in plastic arts has existed since ancient times, and new evidence has been repeatedly found in archaeological excavations.The works of modern artists bring forth new ideas and give people a new feeling at a higher level.One of the most typical representative works is the huge mural "Life, Death and the Four Elements" on the building of the Department of Medicine of the National Autonomous University of Mexico, written by Mexican muralist Francisco Epens.The "four elements" in the painting refer to water, fire, earth and wind, which is a work of metaphor for the life of Indian aborigines, and maize is at the center of this masterpiece, which makes people feel that maize is closely related to life and death under the cultivation of water, fire, earth and wind.[9]
The maize culture has been protected and promoted by people of insight in Mexico.In March 2003, the Mexico City People's Cultural Museum, together with the Mexican Indigenous Society, Chapingo University and other units, held an exhibition entitled "Without maize, there would be no our country", which will last for eight months.On the brochure of the exhibition, there is such an epigram: "Corn is the foundation of Mexican culture, the symbol of Mexico, and the source of our endless inspiration." "We created corn, and corn created us. We always live in mutual nurturing. We are corn people."[9]
Output price
Announce
edit
In 2018, China's maize output was 257.33 million tons.[4]By October 2020, the average price of spot maize had exceeded 2600 yuan/ton, a new high in nearly four years.The price of maize starch rose to about 2900 yuan per ton, an increase of more than 30%.[5]
In 2022, the annual maize planting area in China will be 43.07 million hectares, 250000 hectares less than the previous year;The output of maize was 277.2 million tons, 1.7% more than that of the previous year.[28]
