(1) Technical points of maize parent breeding The hybrid heterosis of the first generation hybrids was the strongest in the corn, and gradually weakened after the second generation. The production was planted everywhere, and the mother of the system was detasseled. Therefore, at the same time as the seed production, It is necessary to multiply the female parent's self-incompatibility for the next season, and the male parent self-crosses in the system for breeding. It can only use one or two times. Long-term use can lead to miscellaneous, so it is also necessary to propagate the male parent and reproduce the parent. The technical points of the submission are:
1. The isolation zone separation method is basically the same as the seed production method, but the requirements are more stringent and the seed purity must be ensured. If space isolation is used, no other corn varieties are required within 500 years around the isolation zone.
2. Strict decontamination is carried out in the three stages of seedling stage, tasselling stage and post-harvest stage. The inbred line is the original species of hybrid maize, and the breeding area is more stringent than the seed area. Carefully observe from the seedling stage, all plants that do not have typical traits must be pulled out, do not be soft.
3. Improve cultivation techniques and improve seeding quality Inbred lines generally have weaker seedlings, less resistance to stress, shorter plants, and lower yield per plant. When breeding, they must be intensively cultivated, apply basic fertilizers, increase density, and improve seed quality. Miao whole Miao.
4. Artificially-assisted pollination Breeding inbred lines are often caused by male or female flowers inconsistent due to physiological or environmental conditions, or due to the lack of pollen in the inbred lines themselves, artificial supplemental pollination is needed.
(B) Hybrid Seed Production Technology
1. It is easy to isolate and segregate corn in selected areas. Regardless of whether the breeding parent can prepare hybrids, isolation zones must be set up to achieve the purpose of safe isolation. The inbred line is called the inbred line isolation zone. The plots for preparing hybrids are called hybrid seed production isolation zones. In addition to ensuring isolation safety, the isolation zones should also use fertile soils with evenly-distributed soil, flat terrain, convenient irrigation and drainage, and drought and flood protection. The plan was completed, and the plants were also grown neatly and consistently. They were consistent in the drawing and were easy to complete in the field and ensure that the quality was achieved in a short time.
1. Segregation method (1) Space segregation means that corn of other varieties is not planted within a certain distance around the isolation area to prevent foreign pollen from being contaminated and the segregation area of ​​inbred breeding and segregation area should be not less than 500 meters. The single-crop seed production area is not less than 400 meters, and the double-crop seed production system is not less than 300 meters. In windy areas, especially when the isolation area is located at the downwind direction of other corn fields, the isolation distance should be appropriately increased.
(2) Time segregation When spatial segregation is difficult, the sowing date of the corn in the isolation zone and the sowing date of the neighboring maize outside the zone can be staggered, and the purpose of isolation can also be achieved. Under normal circumstances, the spring corn offset period is about 40 days, and the summer corn error occurs. The period of about 30 days, due to different natural conditions, according to the situation can be flexible.
(3) Natural barrier isolation is the use of natural barriers such as mountains, villages, houses, and forests.
(4) High-till crop isolation is the isolation of high-till crops (sunflower, reed, sorghum, and kenaf) around the isolation zone. The number of high-stem crops is not too few, and the inbred breeding areas need to grow high-stem crops more than 100 meters. The seed production area is more than 50 meters. The high-stem crops should be properly sown early, and the management should be strengthened so that the plant height of the corn tassels can reach the height of the corn in the isolation zone.
(5) Number of isolation zones The preparation of hybrids requires several isolation zones. Depending on the type of hybrids and the use of seeds, the preparation of a single cross should require the establishment of two parental inbred lines isolation zones and one single line at a time each year. For the isolation and isolation zones, a total of three isolation zones were prepared for the breeding and breeding of three cross-breeding species. At the same time, three parental inbred lines isolation and breeding zones, one single-cross seed production isolation zone and one three-cross seed production isolation zone were set. A total of 5 isolation areas were prepared and a set of double crosses was prepared. Each year, there were 7 isolation zones, ie, 4 parental inbred breeding areas, 2 parental cross-breeding seeding areas, and a double-crossed seeding area. When the parental inbred lines of the two parental single-crossed seeding areas were separately planted, two inbred breeding areas were omitted.
The single seed or three crossbred (using male parent as the father) seed seed replanting in the seed production area, although can reduce the number of isolation areas, but it is often easy to cause mixed seed seed production, reduce the yield of hybrids The effect is not advocated in principle.
(3) The area of ​​the isolation area is mainly based on the number of hybrid seeds required for production and the average yield per unit of the hybrid seed production, and the propagation coefficient of the parental inbred line, and the progeny inbred lines should be proportionately arranged for breeding and hybrid seeding area. Planned breeding of parental inbred seeds and preparation of hybrid seed.
2, specifications sowing (1) adjust the parents of the sowing date, to ensure that the flowering period meet, planting area parent, parental flowering period is the key to the success of seed production. The parental flowering period meets the criterion that female parental silking takes 2-3 days earlier than paternal and tassel loose powder. This is due to the fact that the vigor of the female ear silk can generally maintain more than 7 days, while the paternal loose powder can generally maintain 6- 8 days, but the most flowering on the 2nd to 5th day, the pollen viability generally can only maintain 4-6 hours. Therefore, in the wrong time sowing should follow the principle of "Ningkemu father, not the father and mother."
(1) Parents who have planted a later flowering period are sown in the wrong season, and another parent is replanted after a certain number of days. The number of days in the wrong-time sowing will vary depending on the maturation period, the seeding season, the climate, the soil, and the lyrics of the parents. The parental seeding time adjustment can be based on the number of days of parental fertility difference. When the parent is earlier than the maternal heading, the parental time of wrong seeding should be the parents' heading difference days plus 4-5 days, because under normal circumstances Tassels are drawn 4 to 5 days earlier than the ear. The 2-4 days after silking, the strongest powder, so that the adjustment can reach the flowering period is good, when the parent than the maternal heading late, the father should be sowed early, the number of days of early sowing should be the difference between the two parental heading date The number of days minus 4-5 days, when the maternal parental growth period is basically the same, in order to make the maternal silking season than the original loose powder or soak the seeds of the mother seeds 8-12 hours and then planted with the father.
2 Parents were sowed in stages to prolong the period of loose powder, so that the entire maternal silking period has a large amount of pollen, resulting in the formation of “parental packageâ€, which has a significant effect on improving maternal seed setting rate and reducing baldness and lack of grain. It is also possible to plant a small area of ​​the father's line in the vicinity of the planting area as a powder collection area in case the flowering period is not good enough. As a supplementary pollination and powder collection, the sowing time in the sampling area is later than the isolation area. 6— 7 days.
3 Using leaf inspection method to predict whether the flowering period meets, the method is to regularly select representative plants to check the number of parental leaves, in the case of close to the total parent leaf number, such as the parent's leaf number than the female parent 1-2 behind, indicating that the two parental flowering days can meet each other well. Otherwise, we must promptly adopt remedial measures to promote the control. The method of adjustment is to take early sparse seedlings, early seedlings, and partial application of water to the slow growing or poorly growing parents. Other measures to promote development, can also be combined with foliar spraying 20ppm "90%" and 1% urea mixture, 10-20kg per acre 1-2 times, if the parent is earlier than the mother, can be earlier to the mother Male, cut off the mother's loquat leaves to promote early female spinning.
(2) Properly expand the ratio of parents to the bank, in principle, to ensure that the parental pollen supply is sufficient, increase the proportion of the parent line as much as possible so as to receive more hybrid seeds. Usually, the ratio of parent to parent in the single-cross breeding area is 1:3-4. If parents pollen is adequate and artificial pollination or top-flight cross-breeding, double cross-breeding, and inter-species cross-breeding are performed, the parental ratio can be increased to 1:5-6. In order to tap the potential of seed production from adjusting the proportion of the parents, a 3:0 or 4:0 seed production method can also be used. That is to say, parents are still sowed according to a certain ratio, so that when the father's plants are all loose powder, the parent is immediately removed to improve the ventilation conditions of the parent bank, to create good environmental conditions for the mother's growth and development at the later stage, and to promote the early maturing of seeds. To ensure seed purity and quality.
(3) Improve seeding quality to ensure a full seedling. The maize inbreds have weak seed germination power, slow emergence, and poor seedling growth, and must improve the quality of sowing. At the same time, a full seedling, uniform plant growth, uniform and consistent flowering time, and good flowering time can shorten the time of detasseling and improve the system. Seed quality (4) Improve planting specifications and appropriately increase the planting density in the planting area. Due to differences in parental types, cultivation levels, soil fertility, etc., the objective is to increase the seed yield per unit area. For double-crossing, three-crossing and top-crossing seed production, the planting densities should be smaller because the parent plants are single-crossed and the planting densities should be smaller. In general, mid-late and late-maturing crops have 3000-3500 strains per acre; the smaller plant-type early maturing species Mu 3500-4000 strains. The seedling density of the single-cross seed production in view of the dwarf plantlets of the inbred lines, the yield potential of the individual plants is relatively small. If the fertilizer and water conditions are good, the density can be appropriately increased, the number of panicles per unit area can be increased, and the seed production can be increased.
3. Strictly remove impurities and impurities in order to improve quality, obtain pure seeds, and strictly eliminate impurities when breeding and seed production, generally three times in the field.
(1) In the seedling stage, the seedlings are mixed before the seedlings, according to the seedling's appearance, leaf color, leaf shape,
Leaf sheath color, growth potential and other features to remove impurities.
(2) Before the jointing of males, the cultivars can be removed according to their growth potential, plant shape, leaf width, color, tassel, morphology, male and female ear position, and filament color. The elimination of miscellaneous disorders should be completed before tassel loose powder, so that the purity of the seeds will not be affected by loosening of the mixed strains, and the extracted strains should be brought outside the production area.
(3) After harvesting, the maternity heads in the hybrid seed production area should be re-identified and decontaminated based on the ear shape, grain shape, grain color, axial color of the original parent, and then threshed to ensure storage. The purity of the seed.
4. Male emasculation and artificial-assisted pollination are emasculation of the female parent of the seeding area, which results in pollination by the father, resulting in hybrid seeds. Therefore, emasculation of the female parent is a key technique for obtaining true hybrid seeds. Normal female tassels show about one-third of the parietal lobe can be emasculated, but according to the mother's flowering habits are different, appropriate early or postponed, when emasculation, hold the tassel branches and pull up a little harder Out. When detasseling, attention should be paid to the absence of the parietal lobe, no branching, and one planting at a time. When the fertility of the maternal parent is more than 90-95%, there are still some plants whose tassels have not been extracted and can be taken once. Pull out so as to save time and labour. The tassels to be pulled out must be planted outside the field to be buried or used as fertilizer. Don't throw them around the system to prevent stringing.
Artificial pollination is an important measure to reduce bald and lack of grains and increase seed production. In the flowering peak and late stage of maize tassels, dried dew on a daily basis, a trumpet-type pollinator or kraft paper is folded into triangle bags, or Put the newspaper on the straw hat and make it into the powder collection tray. Collect the pollen from the father in the father's line or in the powder collection area. After removing the pollen from the collected pollen, pour the pollen into the cylindrical pollinator with double gauze on the bottom. , gently shaking on the mother's line has not been pollinated fresh filaments, continuous 3-4 times, each pollination to be at around 11 o'clock before the end of high temperature.
5. Harvesting of the harvested seedlings in the seed collection area shall be timely harvested after ripening, avoiding the rain due to harvesting, the water absorption of the eucalyptus leaves, the germination of the seeds, and the reduction of the quality. Strict implementation of parental income, transportation, share of the sun, points off, sub-reserve, and avoid miscellaneous, generally receive the mother's ear, and other maternal ear all received, shipped back to the drying field, and then receive the parent ear, Ears that fall to the ground should be handled as spikes, except for parents who have obvious trait differences.
Before the threshing, the panicle selection should be carried out to eliminate the miscellaneous panicles, first remove the miscellaneous ear, then take off the parent line and then take off the parent, and the threshing should be carried out to remove the fungus, pods and broken granules, and then drying to achieve safe moisture ( After 14%) can be stored in the storage, when the seeds are bagged, the inside of the bag should be added with a label, indicating the name of the seed, the harvest year, quantity, quality level, and the seed production unit. To be responsible for the fixed person, regularly check the seed moisture content and germination rate, safe storage.
1. The isolation zone separation method is basically the same as the seed production method, but the requirements are more stringent and the seed purity must be ensured. If space isolation is used, no other corn varieties are required within 500 years around the isolation zone.
2. Strict decontamination is carried out in the three stages of seedling stage, tasselling stage and post-harvest stage. The inbred line is the original species of hybrid maize, and the breeding area is more stringent than the seed area. Carefully observe from the seedling stage, all plants that do not have typical traits must be pulled out, do not be soft.
3. Improve cultivation techniques and improve seeding quality Inbred lines generally have weaker seedlings, less resistance to stress, shorter plants, and lower yield per plant. When breeding, they must be intensively cultivated, apply basic fertilizers, increase density, and improve seed quality. Miao whole Miao.
4. Artificially-assisted pollination Breeding inbred lines are often caused by male or female flowers inconsistent due to physiological or environmental conditions, or due to the lack of pollen in the inbred lines themselves, artificial supplemental pollination is needed.
(B) Hybrid Seed Production Technology
1. It is easy to isolate and segregate corn in selected areas. Regardless of whether the breeding parent can prepare hybrids, isolation zones must be set up to achieve the purpose of safe isolation. The inbred line is called the inbred line isolation zone. The plots for preparing hybrids are called hybrid seed production isolation zones. In addition to ensuring isolation safety, the isolation zones should also use fertile soils with evenly-distributed soil, flat terrain, convenient irrigation and drainage, and drought and flood protection. The plan was completed, and the plants were also grown neatly and consistently. They were consistent in the drawing and were easy to complete in the field and ensure that the quality was achieved in a short time.
1. Segregation method (1) Space segregation means that corn of other varieties is not planted within a certain distance around the isolation area to prevent foreign pollen from being contaminated and the segregation area of ​​inbred breeding and segregation area should be not less than 500 meters. The single-crop seed production area is not less than 400 meters, and the double-crop seed production system is not less than 300 meters. In windy areas, especially when the isolation area is located at the downwind direction of other corn fields, the isolation distance should be appropriately increased.
(2) Time segregation When spatial segregation is difficult, the sowing date of the corn in the isolation zone and the sowing date of the neighboring maize outside the zone can be staggered, and the purpose of isolation can also be achieved. Under normal circumstances, the spring corn offset period is about 40 days, and the summer corn error occurs. The period of about 30 days, due to different natural conditions, according to the situation can be flexible.
(3) Natural barrier isolation is the use of natural barriers such as mountains, villages, houses, and forests.
(4) High-till crop isolation is the isolation of high-till crops (sunflower, reed, sorghum, and kenaf) around the isolation zone. The number of high-stem crops is not too few, and the inbred breeding areas need to grow high-stem crops more than 100 meters. The seed production area is more than 50 meters. The high-stem crops should be properly sown early, and the management should be strengthened so that the plant height of the corn tassels can reach the height of the corn in the isolation zone.
(5) Number of isolation zones The preparation of hybrids requires several isolation zones. Depending on the type of hybrids and the use of seeds, the preparation of a single cross should require the establishment of two parental inbred lines isolation zones and one single line at a time each year. For the isolation and isolation zones, a total of three isolation zones were prepared for the breeding and breeding of three cross-breeding species. At the same time, three parental inbred lines isolation and breeding zones, one single-cross seed production isolation zone and one three-cross seed production isolation zone were set. A total of 5 isolation areas were prepared and a set of double crosses was prepared. Each year, there were 7 isolation zones, ie, 4 parental inbred breeding areas, 2 parental cross-breeding seeding areas, and a double-crossed seeding area. When the parental inbred lines of the two parental single-crossed seeding areas were separately planted, two inbred breeding areas were omitted.
The single seed or three crossbred (using male parent as the father) seed seed replanting in the seed production area, although can reduce the number of isolation areas, but it is often easy to cause mixed seed seed production, reduce the yield of hybrids The effect is not advocated in principle.
(3) The area of ​​the isolation area is mainly based on the number of hybrid seeds required for production and the average yield per unit of the hybrid seed production, and the propagation coefficient of the parental inbred line, and the progeny inbred lines should be proportionately arranged for breeding and hybrid seeding area. Planned breeding of parental inbred seeds and preparation of hybrid seed.
2, specifications sowing (1) adjust the parents of the sowing date, to ensure that the flowering period meet, planting area parent, parental flowering period is the key to the success of seed production. The parental flowering period meets the criterion that female parental silking takes 2-3 days earlier than paternal and tassel loose powder. This is due to the fact that the vigor of the female ear silk can generally maintain more than 7 days, while the paternal loose powder can generally maintain 6- 8 days, but the most flowering on the 2nd to 5th day, the pollen viability generally can only maintain 4-6 hours. Therefore, in the wrong time sowing should follow the principle of "Ningkemu father, not the father and mother."
(1) Parents who have planted a later flowering period are sown in the wrong season, and another parent is replanted after a certain number of days. The number of days in the wrong-time sowing will vary depending on the maturation period, the seeding season, the climate, the soil, and the lyrics of the parents. The parental seeding time adjustment can be based on the number of days of parental fertility difference. When the parent is earlier than the maternal heading, the parental time of wrong seeding should be the parents' heading difference days plus 4-5 days, because under normal circumstances Tassels are drawn 4 to 5 days earlier than the ear. The 2-4 days after silking, the strongest powder, so that the adjustment can reach the flowering period is good, when the parent than the maternal heading late, the father should be sowed early, the number of days of early sowing should be the difference between the two parental heading date The number of days minus 4-5 days, when the maternal parental growth period is basically the same, in order to make the maternal silking season than the original loose powder or soak the seeds of the mother seeds 8-12 hours and then planted with the father.
2 Parents were sowed in stages to prolong the period of loose powder, so that the entire maternal silking period has a large amount of pollen, resulting in the formation of “parental packageâ€, which has a significant effect on improving maternal seed setting rate and reducing baldness and lack of grain. It is also possible to plant a small area of ​​the father's line in the vicinity of the planting area as a powder collection area in case the flowering period is not good enough. As a supplementary pollination and powder collection, the sowing time in the sampling area is later than the isolation area. 6— 7 days.
3 Using leaf inspection method to predict whether the flowering period meets, the method is to regularly select representative plants to check the number of parental leaves, in the case of close to the total parent leaf number, such as the parent's leaf number than the female parent 1-2 behind, indicating that the two parental flowering days can meet each other well. Otherwise, we must promptly adopt remedial measures to promote the control. The method of adjustment is to take early sparse seedlings, early seedlings, and partial application of water to the slow growing or poorly growing parents. Other measures to promote development, can also be combined with foliar spraying 20ppm "90%" and 1% urea mixture, 10-20kg per acre 1-2 times, if the parent is earlier than the mother, can be earlier to the mother Male, cut off the mother's loquat leaves to promote early female spinning.
(2) Properly expand the ratio of parents to the bank, in principle, to ensure that the parental pollen supply is sufficient, increase the proportion of the parent line as much as possible so as to receive more hybrid seeds. Usually, the ratio of parent to parent in the single-cross breeding area is 1:3-4. If parents pollen is adequate and artificial pollination or top-flight cross-breeding, double cross-breeding, and inter-species cross-breeding are performed, the parental ratio can be increased to 1:5-6. In order to tap the potential of seed production from adjusting the proportion of the parents, a 3:0 or 4:0 seed production method can also be used. That is to say, parents are still sowed according to a certain ratio, so that when the father's plants are all loose powder, the parent is immediately removed to improve the ventilation conditions of the parent bank, to create good environmental conditions for the mother's growth and development at the later stage, and to promote the early maturing of seeds. To ensure seed purity and quality.
(3) Improve seeding quality to ensure a full seedling. The maize inbreds have weak seed germination power, slow emergence, and poor seedling growth, and must improve the quality of sowing. At the same time, a full seedling, uniform plant growth, uniform and consistent flowering time, and good flowering time can shorten the time of detasseling and improve the system. Seed quality (4) Improve planting specifications and appropriately increase the planting density in the planting area. Due to differences in parental types, cultivation levels, soil fertility, etc., the objective is to increase the seed yield per unit area. For double-crossing, three-crossing and top-crossing seed production, the planting densities should be smaller because the parent plants are single-crossed and the planting densities should be smaller. In general, mid-late and late-maturing crops have 3000-3500 strains per acre; the smaller plant-type early maturing species Mu 3500-4000 strains. The seedling density of the single-cross seed production in view of the dwarf plantlets of the inbred lines, the yield potential of the individual plants is relatively small. If the fertilizer and water conditions are good, the density can be appropriately increased, the number of panicles per unit area can be increased, and the seed production can be increased.
3. Strictly remove impurities and impurities in order to improve quality, obtain pure seeds, and strictly eliminate impurities when breeding and seed production, generally three times in the field.
(1) In the seedling stage, the seedlings are mixed before the seedlings, according to the seedling's appearance, leaf color, leaf shape,
Leaf sheath color, growth potential and other features to remove impurities.
(2) Before the jointing of males, the cultivars can be removed according to their growth potential, plant shape, leaf width, color, tassel, morphology, male and female ear position, and filament color. The elimination of miscellaneous disorders should be completed before tassel loose powder, so that the purity of the seeds will not be affected by loosening of the mixed strains, and the extracted strains should be brought outside the production area.
(3) After harvesting, the maternity heads in the hybrid seed production area should be re-identified and decontaminated based on the ear shape, grain shape, grain color, axial color of the original parent, and then threshed to ensure storage. The purity of the seed.
4. Male emasculation and artificial-assisted pollination are emasculation of the female parent of the seeding area, which results in pollination by the father, resulting in hybrid seeds. Therefore, emasculation of the female parent is a key technique for obtaining true hybrid seeds. Normal female tassels show about one-third of the parietal lobe can be emasculated, but according to the mother's flowering habits are different, appropriate early or postponed, when emasculation, hold the tassel branches and pull up a little harder Out. When detasseling, attention should be paid to the absence of the parietal lobe, no branching, and one planting at a time. When the fertility of the maternal parent is more than 90-95%, there are still some plants whose tassels have not been extracted and can be taken once. Pull out so as to save time and labour. The tassels to be pulled out must be planted outside the field to be buried or used as fertilizer. Don't throw them around the system to prevent stringing.
Artificial pollination is an important measure to reduce bald and lack of grains and increase seed production. In the flowering peak and late stage of maize tassels, dried dew on a daily basis, a trumpet-type pollinator or kraft paper is folded into triangle bags, or Put the newspaper on the straw hat and make it into the powder collection tray. Collect the pollen from the father in the father's line or in the powder collection area. After removing the pollen from the collected pollen, pour the pollen into the cylindrical pollinator with double gauze on the bottom. , gently shaking on the mother's line has not been pollinated fresh filaments, continuous 3-4 times, each pollination to be at around 11 o'clock before the end of high temperature.
5. Harvesting of the harvested seedlings in the seed collection area shall be timely harvested after ripening, avoiding the rain due to harvesting, the water absorption of the eucalyptus leaves, the germination of the seeds, and the reduction of the quality. Strict implementation of parental income, transportation, share of the sun, points off, sub-reserve, and avoid miscellaneous, generally receive the mother's ear, and other maternal ear all received, shipped back to the drying field, and then receive the parent ear, Ears that fall to the ground should be handled as spikes, except for parents who have obvious trait differences.
Before the threshing, the panicle selection should be carried out to eliminate the miscellaneous panicles, first remove the miscellaneous ear, then take off the parent line and then take off the parent, and the threshing should be carried out to remove the fungus, pods and broken granules, and then drying to achieve safe moisture ( After 14%) can be stored in the storage, when the seeds are bagged, the inside of the bag should be added with a label, indicating the name of the seed, the harvest year, quantity, quality level, and the seed production unit. To be responsible for the fixed person, regularly check the seed moisture content and germination rate, safe storage.
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