GB/T 17315-2026Technical code of practice for maize seed production (English PDF)

4.1 Production of the original seed

4.1.1 Develop a plan Before producing the original seed, a production plan is formulated, the process is strictly followed, and production records are established.

4.1.2 Site Selection Production sites should be spatially isolated and at least 500 meters away from other corn pollen sources (with sufficient protective measures to ensure no...). For pollen sources that may be contaminated, a 500m isolation distance may not be necessary; alternatively, barrier isolation or time-based isolation methods can be used. The fertility of the producing fields must be considered. The soil is uniform, fertile, and easy to irrigate and drain, ensuring stable yields.

4.1.3 Sowing Before sowing, the land should be carefully prepared, and seeds should be selected and coated. Sowing should be done at the appropriate time with sufficient moisture, or drip irrigation technology can be used for "dry sowing and wet emergence" to ensure uniform and strong seedlings.

4.1.4 Removing impurities During the seedling stage, jointing stage, tasseling stage, and before pollen shedding, it is essential to promptly, strictly, and thoroughly remove any unwanted or atypical plants. This should be done before drying and storing, and before sun-drying and threshing. Miscellaneous and diseased ears should be strictly removed.

4.1.5 Storage Individual harvesting and storage are required, with complete records filled out. Labels should be affixed to both the inside and outside of the packaging. The principle of original seed production is one-time propagation for batch use; continuous propagation is not advisable. It should be stored for more than 3 generations. Storage method shall comply with GB/T 7415, and labeling shall comply with GB 20464.

4.1.6 Seed Testing Seed quality inspection should be conducted according to GB/T 3543 (all parts), including seed purity, moisture content, germination rate, authenticity, and purity. Non-GMO seeds still need to undergo GMO component testing, while GMO seeds need to undergo transformant authenticity and GMO purity testing. Testing methods... National standards or relevant industry standards shall be adopted. The routine detection targets for genetically modified maize components include commonly used universal elements, target genes, and transformant events. Authenticity testing of transgenic maize seed transformants. The transgenic seeds contain only the labeled transgenic components; the testing targets include the labeled... Transformants, as well as commonly used universal elements, target genes, and transformant events. For inbred lines, transgenic purity testing indicates homozygosity of transformants. The proportion of individuals.

4.1.7 Threshold requirements for accidental contamination (AP) of genetically modified organisms In non-GMO maize varieties, no GMO components should be detected in the inbred lines. In GMO inbred lines, no other GMOs not listed should be detected. Element.

4.2 Production of seeds from parental inbred lines

4.2.1 Site Selection Production sites should be spatially isolated and at least 300 meters away from other corn pollen sources (with sufficient protective measures to ensure no...). For pollen sources that may be contaminated, a 300m isolation distance may not be necessary; alternatively, barrier isolation or time-based isolation methods can be used. The fertility of the producing fields must be considered. The soil is uniform, fertile, and easy to irrigate and drain, ensuring stable yields.

4.2.2 Sowing Same as 4.1.3.

4.2.3 Removing impurities Same as 4.1.4.

4.2.4 Storage Same as 4.1.5.

4.2.5 Threshold requirements for accidental contamination (AP) of genetically modified organisms Same as 4.1.7.

4.3 Flowchart of inbred line original seed and parental seed production The production process of inbred lines and parent seeds is shown in Figure 1.

5.2 Isolation

5.2.1 Spatial Isolation When spatial isolation is required, the seed production base should be at least 100m away from other pollen sources.

5.2.2 Barrier Isolation Where the spatial isolation distance is less than 100 meters, a barrier isolation zone should be set up around the seed production base. Non-GMO maize hybrids Barrier isolation is implemented by planting dense-leaved, tall-stalked crops to create barrier isolation zones. These zones must be at least 5 meters wide and 3 meters high. Another type of parent line with a width of not less than 5m. Biological isolation of genetically modified maize hybrids is achieved by establishing biological isolation zones through the planting of dense-leaved, tall-stalked crops, with a width of no less than A buffer zone of at least 5 meters in length and at least 3 meters in height, along with a non-GMO parental line at least 5 meters in width, should be planted to reduce pollen dispersal; non-biological methods should be employed. When setting up barriers, the height and distance of the barriers must meet the requirements for safe production.

5.2.3 Time Isolation When using time isolation, the difference in sowing period for spring seed production should be no less than 40 days, and the difference in sowing period for summer seed production should be no less than 30 days.

5.3 Sowing Before sowing, effective measures should be taken to strictly remove self-growing seedlings to reduce the impact of the previous crop on seed production in the next crop. The authenticity and purity of parent lines should be verified, and genetically modified lines should be included. Because the authenticity of the transformants and the purity of the transgenic lines should be verified, seed selection, coating, and germination rate testing should be performed; based on the characteristics of the parents and Based on local natural conditions, determine the appropriate parent seeding period, seeding rate, row ratio, and density.

5.4 Removing impurities

5.4.1 Removing impurities from the paternal parent Hybrids of the male parent should be completely removed before males emerge.

5.4.2 Removing impurities from the parent plant Hybrid plants of the mother plant should be completely removed before emasculation.

5.5 Castration For the female parent, the male spike should be removed promptly, cleanly, and thoroughly before pollen shedding, by removing 1 to 2 leaves.

5.6 Remove seedlings and tillers from the mother plant. Before the emasculation of the female parent is completed, weak seedlings that have not been emasculated and tillers of the female parent should be removed from the field in a timely manner.

5.7 Artificial pollination To ensure good pollination in seed production fields, artificial pollination can be carried out as needed.

5.8 Removal of the paternal parent After pollination, the male parent plants should be completely removed and taken out of the seed production field for disposal.

5.9 Harvest Harvest the grains promptly after they have reached physiological maturity, and dry or bake them to prevent frost damage and contamination. Before threshing, conduct rigorous ear selection to remove impure and diseased ears. Genetically modified (GM) and non-GM crops must be handled and stored separately and clearly labeled to ensure traceability of the process.

5.10 Anti-hybridization For mechanical sowing and harvesting, ensure that the mechanical sowing and harvesting equipment and storage containers are cleaned before operation to prevent mixing.

5.11 Threshold requirements for accidental contamination (AP) Same as 4.1.7.

5.12 Shelter Seed Requirements Genetically modified maize seeds containing insect-resistant traits should be mixed with shelter seeds according to regulations, including the mixing ratio and seed quality of the shelter seeds. It should meet the requirements of relevant regulations. To ensure consistency in the field, shelter seeds should preferably be of similar varieties, grown in the same or similar production environments. Production under certain conditions.

6.1 Inspection Items and Basis

6.1.1 Inspection of Production Base The key focus is to determine whether the isolation conditions, previous crop conditions, and planting specifications meet the requirements.

6.1.2 Seedling Stage Inspection At least two inspections should be conducted, focusing on seedling emergence, timely seedling placement, seedling thinning, seedling growth, leaf sheath color, leaf shape, and leaf color. The typicality of the seedlings should be observed, and weeding should be carried out during the seedling stage. At the same time, corn diseases and pests should be inspected and prevented, and the growth process should be marked and the flowering period predicted.

6.1.3 Flowering period inspection The focus of the inspection should be on the removal of weeds and tassels, as well as the inspection and control of corn diseases and pests. This should be based primarily on plant height, plant type, leaf shape, leaf color, and tassel shape. The examination and removal of impurities were based primarily on the typical characteristics of the female parent in the seed production field, including the number of branches, glumes, anther color, and filament color. The inspection covered the removal of weak seedlings and tillers, including whether they were removed in a timely, clean, and thorough manner, and the handling of the removed male ears. During the field inspection period at the flowering stage, field inspectors moved between different seed corn production plots, genetically modified seed production bases, and non-genetically modified seed production bases. Do a good job of cleaning to prevent human-caused pollution.

6.1.4 Harvest Inspection Check for miscellaneous plants, pests and diseases, and any instances of incorrect or mixed harvesting.

6.1.5 Pre-threshing inspection The focus of the inspection is on the typicality of traits such as ear type, grain type, grain color, and ear cob color.

6.2 Processing of Inspection Results Each inspection should be conducted according to the standards in Appendix A, and the inspection results should be recorded in Appendix B. If any non-compliance with the requirements of this document is found, the production department should be notified. The department submitted a written report and promptly proposed rectification measures. Upon review, those items that still failed to meet the requirements were recommended for scrapping.