How to remove impurities and emasculate maize hybrid seed production.

In order to improve the quality of seed production and ensure the purity of seeds, impurities must be strictly removed and emasculated in the process of hybrid corn seed production.

(1) Remove impurities. Impurity removal is generally carried out in three phases and five times.

(1) Before sowing. Before sowing, impurities, chaff, mildew, diseases, moth-eaten grains, etc. are removed from the seeds according to their color, size and grain type.

② Remove impurities in the field. Impurity removal in maize seed production field is generally carried out in three times. First combination, plant spacing, impurity removal. According to the characteristics of parents' seedlings, such as leaf color, leaf sheath color, leaf shape, growth potential, leaf edge color, etc. Keep seedlings strictly and remove impurities. The female parent should keep the same size of seedlings, and can keep two seedlings when they are short of seedlings, but it is not recommended to replenish seedlings, which is called "Que Ning does not replenish seedlings"; Parents should save seedlings of different sizes to prolong the pollen transmission period. The second pass is to further strictly remove impurities when jointing. According to parents' plant height, plant type, leaf color, etc. The third time, I went to do chores before smoking male powder. This is a critical period to ensure the purity of seeds, which must be carried out seriously and strictly controlled. Check the impurity removal of male parents one by one according to the number of branches of male ears and the color of anthers, so as to ensure that the pollen of hybrid plants will never spread in the isolation area. The impurity removal of the female parent is based on the filament color of the female ear. All miscellaneous plants must be uprooted. According to the national regulations, if the cumulative rate of scattered plants of male parents exceeds 0.5%, the seed field will be scrapped.

③ Harvesting before threshing. According to ear type, grain type, grain color and axis color, pick out miscellaneous ears. It can only be threshed when the rate of miscellaneous ear is below 1.5% after inspection by technicians.

(2) The female parent is completely castrated. In the seed production area, the female parent is completely emasculated, so that it can only accept the pollen of the male parent and bear fruit, so that the seeds produced by the female parent plant can be hybrid seeds. The emasculation of female parent plants should be timely, thorough, clean and brought out. Timely means to pull out the male ear of the female parent plant before it is scattered; Thorough cleaning refers to pulling out all the male ears of the female parent in the whole field in the seed production area, without leakage or residual branches; Taking out refers to taking the picked tassel out of the seed field with a bag and burying it in the soil or making feed. In order to ensure the quality of castration, we should often go to the seed production field for inspection a few days before castration so as to castrate in time. The castration time can be carried out after the dew is dry, in the morning and afternoon, and once every other day in the early stage of castration, but it must be carried out twice a day in full bloom and late stage, rain or shine. At the end of emasculation, special attention should be paid to cutting off the weak plants in the mother bank at one time to prevent the loose powder from being missed, and all previous efforts will be wasted, which will affect the emasculation quality. When using advanced castration (castration), before the top leaf of the female parent in the seed field is exposed, the top leaf is peeled off or pulled out together with the top leaf. Taking early emasculation can promote the development of female ear, because nutrition is concentrated on female ear, and it can be spun 3 ~ 5 days in advance. Therefore, early castration should be adopted, and the sowing date of parents should be adjusted to ensure that parents meet at this flowering period.