Good varieties and seeds are the basis for a good harvest. Variety selection is the first step in corn production. There are significant differences between varieties in terms of growth period, yield level, disease resistance, drought tolerance, disease resistance, lodging resistance and adaptation area. A variety that performs well in one area may perform poorly in other areas, and production often involves poor choice of varieties or poor quality seeds that result in reduced yields or even total production. How to choose the best varieties and seeds that are suitable for the needs of corn producers is an important issue. It is generally believed that the following points should be noted: Select a variety that has been tested for at least 3 years in the local area. After three years or more of trials and demonstrations in the local area, it is basically possible to know the suitability of the varieties in the area. Choosing breeds that perform better over many years will have less chance of producing catastrophic losses in production. Choose a variety that can mature normally in your area. Choose mid-early-maturing and mid-late-maturing varieties that can normally mature in the region, and use less late-maturing varieties. Before the first heavy frost in autumn, grain corn must reach a physiological maturity or a black layer, otherwise the grain moisture content is higher, the bulk density is lower, and the quality of the product is reduced. With the change of climate, autumn creams come late in a few years, and late frosts for two or three consecutive years often make people less vigilant, and grow some varieties with longer growth periods and cause greater losses. This occurs frequently in China's northeastern spring maize area and northern China's northern summer corn area. Choose varieties with high potential for production and wide adaptability. The yield potential of varieties with similar growth periods can vary greatly. The productive potential of the variety cannot be determined by the size of the ear, the number of ear rows, the number of grains per row, the grain depth, the rate of double panicles, and the special characteristics of erection (compactness) and flattening of the leaves. The production potential of the variety is reflected in the level of yield. Therefore, it is necessary to select varieties based on the yield results of the trials rather than the traits such as the size of panicles and the rate of double panicles. Due to the unpredictability and variability of climate, varieties with higher yield levels in multiple sites, multiple regions, and multiple environments should be selected. Choose a high resistant lodging variety. It is very important to choose lodging-resistant varieties, especially windy areas. Although lodging has a close relationship with the environment and cultivation measures, the genetic difference of the breed is also an important factor that influences lodging. The lodging generally has lodging during the period of reproduction and lodging after maturity. Lodging during breeding is more harmful, and severe can lead to abortion; while lodging at late growth stage or after physiological maturity has little effect on yield, it often results in deterioration of quality, rotting of grains, aggravation of rodent loss, difficulty of harvest, and harvesting. The cost increases. Select resistant or resistant varieties. Disease is an important disaster in corn production. In recent years, the main feature of breed renewal is the continuous improvement of disease resistance. The types of major diseases in different regions and the degree of the disease are different. For example, head smut is the main disease in corn production in the northeastern spring maize region, and it is less harmful in the Huanghuai corn area. The disease resistance of the varieties, in addition to the characteristics of the reference varieties, the evaluation tests of the local seed companies or the agricultural technology promotion departments, also refer to the cultivation experience of other farmers. More mature and more varieties with planting. Multi-maturity and multi-cultivation planting is one of the most effective measures to reduce pests and adverse environmental conditions such as drought resistance and low temperature. Multi-maturity and multi-species band spacing planting, such as early-maturing, medium-maturing and late-maturing varieties with 25%-50%-25% collocation, can reduce the drought-caused flower failure and poor pollination resulting from drought At the same time, it can not only make full use of the light and heat resources in the long growth period, but also reduce the damage of the early morning frost. In addition, the combination of multi-maturing varieties can increase the genetic diversity of maize and reduce the loss caused by the loss of variety resistance. Special varieties are selected for special needs. Due to special needs, such as feeding or processing, special corn varieties such as high starch varieties, high oil varieties and high quality protein corn varieties, waxy corn, and sweet corn are selected. Choose a practical variety. At present, most peasant households are interested in new varieties, which reflects the improvement of farmers’ own technological production levels and their eagerness for new technologies. However, it should be pointed out that new varieties are not necessarily suitable for demand, and they must be selected in relation to the level of production management and land fertility. Matching varieties. In addition, under the current management situation, some new varieties have not been tested in the local area for many years, and it is not clear whether they can adapt to the local environment. The risk of planting is relatively large. Therefore, the selection of varieties should be based on practicality, and must not be new and demanding. Choose high quality seeds. Seed quality has a great influence on yield, and its impact sometimes exceeds the difference in yield between varieties. Therefore, not only good varieties but also high-quality seeds should be selected for production. At this stage, the indicators for measuring seed quality in China mainly include species purity, seed clarity, germination rate, and moisture. The state has made clear provisions on the purity, cleanliness, germination rate, and moisture content of corn seeds. The purity of the first-class seed seed is not less than 98%, the cleanliness is not less than 98%, and the germination rate is not less than 85%. The moisture content is not higher than 13%; the secondary seed seed purity is not less than 96%, the clarity is not less than 98%, the germination rate is not less than 85%, and the moisture content is not higher than 13%. The detection and supervision of maize hybrid seeds in China adopts the method of “Limiting the lower limit of qualityâ€, that is, it cannot reach the target of the second-level seeds. In principle, it cannot be sold as seeds.
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