This document summarizes the process of hybrid seed production for maize. It discusses selecting appropriate parent lines and maintaining isolation distances between male and female lines. Key steps include planting ratios, detasseling the male plants, roguing undesirable plants, and harvesting when seeds reach proper maturity. Multiple inspections are needed to ensure genetic purity is maintained throughout production. Proper post-harvest handling and storage is also important for high quality hybrid maize seed.

1. HYBRID SEED PRODUCTION TECHNOLOGY OF MAIZE By: MOHAMMAD SAFAR ALIZADAH NOORI

4. Flour corn: Flour soft maize as kernels , which are compose entirely of soft starch Pop corn: The grains unusually small pointed and contain an even higher per cent of hard starch than flint maize Pod maize: It is an unusual type of maize each kernel of which enclosed within the lemma and palea which are well develop Waxy maize: Waxy maize is so named because of the some what waxy appearance of the kernels

5. Floral biology The monoecious corn plant has female flowers that develop on the side of the plant and emerge from the leaf node. The inflorescence is unisexual and monoecious. Staminateinflorescence is terminal and known as tassel and pistillate is axillary and called as cob

7. Pollen shedding begins 1-3 days before the silks emerge from the cob.

8. It is estimated that a normal tassel produces 2,50,00,000 pollen grains.

9. Pollen is viable for 12-18 hours. Silk remains receptive for 8-10 days.

11. Hybrid seed production Hybrid seed of maize may generally be produced from following different cross combinations Single cross hybrid: (AXB) e.g. DMH-2(CI-4 X KDMI-10) NAH-2049(147-F2#89 X MAI-105) (Nithyashree) Double cross: (AXB) X (CXD) e.g. Deccan (CM 104 x CM 105) x (CM 202 x CM 201) Ganga-1 (CM 101 x CM 102) x (CM 200 x CM 202) Three way cross: (AXB) X C e.g. Ganga -5 (CM 202 x CM 111) x CM 500 Double top cross : (AXB) X Composite e.g. Ganga safed, Histarch, Ganga 4.

13. Non-synchronization of flowering

14. Genetic drift

15. Detasseling

16. Mechanical admixtures

17. Rouging

18. Physiological maturity of the crop

19. Harvest seed crop

25. Mark the male rows with marker to avoid mistake in detasseling.

27. Donot carry the tassel through the field as any fall of pollen may lead to contamination.

28. Donot practice, improper, immature and incomplete detasseling.

29. Improper detasseling: a portion of the tassel is remaining in the plant while detasseling.

30. Immature detasseling: carrying out detasseling work when the tassel is within the leaves.

31. Incomplete detasseling: the tassel is remaining in lower or unseen or unaccounted in within the whole of leaves.

33. Harvest seed crop: the seed crop should be harvested when moisture content falls to 20-25% and harvest the male row first and remove from the field and then harvest the female rows. Post harvest operation : Cobs sorting: Remove sheath and check for kernel colour, shank colour , disease cobs, kernel arrangement etc. Shelling : moisture content 15 % and mechanical cob shellers and also manual rubbing against stone are used. Improper shelling leads to 48 % damage to kernel, growth of storage fungi and also pericarp damage, to identify the pericarp damage a crack on the pericarp and also by ferrichloride test or Tz test.

34. Seed production technology

36. About 85% of the total acreage under maize is grown during monsoon because of the fact that the crop stops growing if the night temperature falls below 15.60 C or 600 F.

37. Maize crop needs more than 50% of its total water requirements in about 30 to 35 days after tasseling and inadequate soil moisture at seed filling stage results in a poor yield of shriveled seeds.

38. Maize needs bright sunny days for its accelerated photosynthetic activity and rapid growth of plants.

40. Seed source Certified or foundation seeds are to be procured from the approved certified agencies

41. Seed rate and Spacing A plant population density of 50-55 thousands/ha is ideal to attain maximum yield. Hybrids: Female 10kg/ha Male 4 kg/ha Spacing : 60 - 75cm row spacing and plant to plant 25 -30cm.

43. NPK: 200:100:100kg /ha

45. Methods of planting and Earthingup Sowing depth (3-5cm) must be uniform to get a uniform emergence. The planting may be done as follows Planting on the ridge Planting in furrows Planting on flat bed with no earthing up Planting on flat bed. Earthing up after 40-45 days of days of planting

46. Isolation Distance Field standards for isolation For Foundation single crosses and hybrid of certified class

47. Isolation distance Isolation distance depends on seed yield of the lines and size of the plot. The required minimum isolation distance is 200 m in certified seed production from the contaminant source. Four pollen parent border rows in the field is to be inspected four ha or less in size. The isolation distance may be decreased by 5 m for each increment in 2 ha in size of the plot to a maximum of 16 ha. Here the isolation distance may be further decreased by 12.5 m for each additional border rows to a maximum of 16 pollen parent border rows.

48. Border rows Borders rows must be planted in the seed field or adjacent to it, but in no case separated by more than five meters from the field. Borders rows must be planted all along and opposite to the contaminating maize. There should be a reasonable stand of border row, i.e., there must not be gapes in the border rows. Border rows must have been planted using the seed rate and spacing adopted for the seed crop. The area planted under the border rows is taken into consideration while modifying the isolation distance.

49. Contd.. natural barriers such as tall thick trees, buildings…etc between in the seed and contaminating fields shall not be a substitute to border rows. Border rows must be planted with seed used for planting male rows in the seed field. Seed saved from male rows of the previous production of the same cross can not be used for planting of border or for planting with isolation distance.

50. Rouging: It is the process of removal of voluntary plants, off-types, other crop plants, pollen shedders, and objectionable weed plants from the seed field before either of the crops comes to flowering.

51. Field Inspections First inspection: The field should be inspected to verify that it is properly isolated and free of volunteer plants. Second inspection: During the vegetative growth phase. Isolation should be checked, along with the presence of disease, insect pests, or weed infestations. At this stage, off-type and disease plants may be rouged. Third inspection: made just prior to and during flowering. At this time the maize seed field is most susceptible to genetic contamination from windblown pollen coming from off-type plants within the field or other maize varieties in surrounding fields. Plants that are off-type or diseased, along with harmful weeds, must be removed at this time. Fourth inspection : A pre-harvest or harvest inspection may be conducted as the crop reaches maturity and the seed has lost a significant portion of its moisture content.

55. Polysora rust,

56. Tropical rust,

57. Black kernel rot,

58. Maize mosaic virus I (MMV),

59. Turcicum leaf blight,

60. Common smut and

61. Head smut.

62. Shoot fly and cob borer are the important insects.

63. Control measures: Spray Mancozeb 2.5g/lit or Dithane M-45 spray can be taken (0.4%) as soon as first symptoms are observed and it can be repeated at 10 days interval till flowering.

65. Storage Seeds stored in high density polythene bag (700 gauge) and poly lined gunny bag with reduced moisture of 8 per cent retained seed quality parameters upto 15 months compared to seeds stored in cloth bag and gunny bag.

66. Field standards Seed standards for hybrids:

67. Standards for Germination test

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