What is the reason for the decrease in the purity of corn seeds? How to improve?

The yield of maize is also closely related to the purity of varieties. In the same variety, the yield of planting high-purity seeds is higher than that of low-purity seeds, and the yield is decreasing with the decrease of purity. What is the reason for the decrease in the purity of corn seeds? How to improve? Let's get to know it together.

First, what are the reasons for the decrease in the purity of corn seeds?

1. Biology is mixed. The conditions of the quarantine zone and impurity removal did not meet the national standards, and different varieties of pollination caused biological confusion.

two。 It is not timely to get rid of male in seed production. The male ear of some parent inbred lines blossomed and scattered powder in the bract, but failed to get rid of the male in time, resulting in self-crossing.

3. Seed harvesting, threshing and storage are not strictly controlled, miscellaneous ears are not strictly removed according to quality standards, and threshing machines and sorting machines are not cleaned thoroughly, resulting in mechanical confusion. Every important link of maize seed production will lead to the decrease of seed germination rate. The parents of seed production field are greedy for green and late ripening, the filling is not full, and the water content is high. Seed germination ability can be reduced when seeds suffer from low temperature, cold injury and frost at milky stage, and are forced to be harvested, and ears suffer frost injury in the sun field after harvest. Seeds are stored in dark, damp and other poorly closed warehouses after they are stored. These factors can lead to the decrease of seed germination rate.

Second, how to improve the purity of corn seeds when it is reduced?

1. Screening and preserving pure inbred lines

The first is to select all kinds of inbred lines with completely stable characters; the second is to strictly set the isolation area during propagation; the third is to reduce the propagation algebra and set up a special person for year-by-year bagging and purification.

two。 Set up quarantines according to standard

The first is spatial isolation, which requires that the spatial isolation between different varieties is not less than 200m. The second is natural barrier isolation, which requires that under the premise of spatial isolation of not less than 100m, natural barriers such as villages, roads, forest belts and high walls should be used to isolate, and 2m 5m male parent rows, sorghum, high-pole flax and other crops should be planted at the edge of the seed production field to protect them.

3. Strictly remove impurities

Impurity removal at seedling stage: impurity removal at seedling stage was carried out at 4-5 leaves, and the time of impurity removal for plots with many variants and serious seedlings should be postponed, selected at 6-7 leaves, and adhered to the principle of "go to the big, go to the small and stay in the middle".

Removal of miscellaneous before male removal: removal of miscellaneous before male removal was carried out in late June. According to the physiological characteristics of parents, such as plant height, stem thickness, leaf color, leaf width and width, and the angle between leaf and stem, miscellaneous and heteromorphic plants were removed. With the attitude of "would rather kill by mistake than miss", the miscellaneous removal work of male parents should be strictly implemented.

4. Accurately judge the florescence and get rid of male in time.

Timely, clean and thorough male removal is the key to ensure the purity of corn. Maize castration in Hexi irrigation area is mainly from late June to mid-July. Florescence should be accurately judged, labor should be organized in advance, and the time of castration should be arranged reasonably. Do the first male removal to remove 95% of the male ear, remove the remaining 5% of the male ear twice, and check the missing plants in the middle and around the ridges three times. In the whole process of castration, we should strictly ensure that there is no hindrance, rain or shine, and continuous irrigation.

5. Cut off the male parent at the right time

The male parent can be cut off when 80% of the female parent filaments wither after pollination, which is usually carried out from late July to early August according to the maturity of the variety. This work should be done early rather than late, so that there is no exposure and no residue.

6. Earnest panicle selection in the later stage

Panicle selection after harvest to pre-processing is the guarantee to improve seed purity. Strict panicle selection should be made before and after seed harvest in late September, and the last panicle inspection should be made when the ear enters the processing plant, such as drying, processing line transportation and so on. At the same time, mechanical mixing among varieties should be avoided in transportation, drying, threshing and other links.