The characteristics and cultivation techniques of sweet corn
First, the type and characteristics of sweet corn
The essential difference between sweet corn and common corn is that sweet corn carries a recessive mutation gene that significantly improves grain sugar content. Due to the different genes controlled, sweet corn in production is often divided into three types: sweet corn, super sweet corn and sweetened corn.
(1) The total sugar content of common sweet corn during the milk ripening period is generally between 8% and 16%, which is usually 2 times that of normal corn. The water-soluble polysaccharide content of the grain is extremely high, reaching 25% of the dry weight of the grain. It is common corn. 10 times. As the sugar content of the grain and the content of the water-soluble polysaccharide increase, it not only has a certain sweetness, but also has a unique twist, has a good flavor and is easily absorbed and utilized by the body. Normal sweet corn usually converts starch to starch rapidly after 1-2 days of picking, and the sweetness decreases. In the mature grains, the starch content is significantly less than that of normal corn. The grain shrinks and shrinks, generally translucent.
(b) Super-sweet corn kernels have extremely high sugar content, with a total content of 25%-35%, especially high sucrose content, which is usually 10 times that of ordinary corn and more than 1 times higher than that of ordinary sweet corn. The mature super-sweet corn kernels contain a small amount of starch, and the seeds shrink and shrink in appearance and appear opaque. The remarkable feature is that the sweetness is significantly increased, and the sugar is converted into starch at a slower speed than ordinary sweet corn. Therefore, during harvesting, corn lacks soluble sugar, and its peel is thick, its softness is poor, its contents are small, and its flavor and flavor are not good. It is not appropriate to make canned food because of the low seed germination rate caused by grain pods and weak seedling viability.
(C) Strengthening sweet corn is divided into whole sweet corn and semi-sweet corn. The milk content of the former can reach more than 30% during the milky period, which is equivalent to that of the super sweet corn. The water-soluble polysaccharide content is equivalent to ordinary sweet corn. It has both the advantages of ordinary sweet corn and super sweet corn. It has high grain content and good flavor. At the same time, the harvest period is long and the shelf life is long. The starch content of mature grain is slightly lower than that of ordinary sweet corn, but significantly higher than that of super sweet corn. The sugar content of semi-sweet corn during the milk ripening period is 50%-60% higher than that of common sweet corn, and the edible flavor is obviously better than that of common sweet corn and close to whole sweet corn. The seed germination rate and growth at the seedling stage are similar to that of ordinary sweet corn, which is significantly better than that of super sweet corn. The grain of the ear often has the same flower type as yellow and white, which is favored by people.
Second, the growth and development characteristics of sweet corn
Sweet corn kernels are generally lighter in weight than normal corn and exhibit shriveledness. Seed 1000-grain weight: Normal sweet corn is equivalent to 70% of normal maize, and super-sweet corn is equivalent to 50% of normal corn. Strong sweet corn is slightly lower than common sweet corn, but significantly higher than super sweet corn. The main reason for the lightness of sweet corn kernels was that sweet genes inhibited the starch synthesis in grains and caused less accumulation of starch in the endosperm, which did not meet the needs of seed germination and self-nutrition before the three-leaf stage of seedlings. The germination rate and seedling growth were significantly inferior to those of ordinary corn. The poor growth of shoots and the lack of photosynthetic products lead to slow rooting, low number of roots, and weak roots, which make it difficult to form robust and well-developed root systems. As a result, seedlings are weak, seedling growth is irregular, and leaf growth is slow, making it difficult to cultivate strong seedlings. After silk spinning, the sweet potato gene inhibited the starch accumulation of endosperm and the conversion of free amino acids to protein, which caused the photosynthetic product of the leaves to be hindered from transporting to the grain and inhibited the photosynthetic efficiency of the leaves, resulting in premature aging in the late growth stage.
III. Cultivation Techniques for Sweet Corn
(1) Variety selection should be based on the right high yield, good fresh yield per mu 500 kg, suitable sweetness, pure aroma, soft texture, rich nutrition, uniform ear size, thin seed coat, yellow grain, white cob, seeds The varieties with high bud rate, strong seedling potential, and good resistance to ear rot and ear pests, and strong lodging resistance, such as Tianyu No.2, No.4 and No.6 of the Chinese Academy of Agricultural Sciences, Shanxi Agricultural Sciences The hospital's Jin Tian No. 1 and so on.
(ii) Selection of Sowing Time According to the special use of sweet corn and the short harvesting period, in order to extend the time of listing or processing, it is possible to adopt the method of staged sowing on production to match early, middle and late-maturing varieties. The earliest sowing date, when the temperature is stable through 12 °C can be sowing, as long as the minimum sowing date can ensure that the temperature during the harvest can be above 18 °C or. The use of mulching can be advanced 7-10 days; taking thin seedlings can be advanced 10-15 days. Our district generally sows from April to mid-July.
(3) Isolation and planting shall not allow any type of sweet corn to cross-bred with each other, and it must not be crossed with normal corn starch powder, nor can it be hybridized with normal corn starch powder. Otherwise, due to the complementary function of genes, the seeds of contemporary crops will lose their sweetness. It becomes normal corn. No matter what kind of sweet corn is grown, it must be planted. The isolation area requires more than 400 meters. Time difference isolation can also be adopted, requiring a difference of more than 30 days in flowering time.
(D) Fine Seeding The cultivation of sweet corn should be like the cultivation of vegetables, choose a higher fertility, deep loose water, permeability of a good block. Seeds should be sorted and graded to remove insect seeds, bad seeds and moldy seeds. When sowing, the soil moisture is suitable, sowing should not be too deep, cover soil 3-5 cm, and ensure that the depth of cover soil consistent, 2-3 seeds per seed. Applying base fertilizer between rows of holes, generally 35-45 kg of ammonium diammonium phosphate, 0.5-1.0 kg of zinc sulfate. At the same time, we must pay attention to the control of underground pests
(5) Planting density and population control The general high-yield requirement density is 5000-6000/667m2. The density of early-maturing varieties is slightly higher, and the spring sowing of the same variety should be higher than that of summer sowing. In order to ensure the appropriate number of panicles and improve the uniformity, when adopting group control measures, based on the improvement of the sowing quality, the number of emergences is two times the number of suitable panicles. 3-4 leaves according to the seedlings partial application Miao Fei promote balance, 5-6 leaves in addition to weak seedlings, and according to the appropriate density on the definition of seedlings. At the same time, according to the characteristics of sweet corn with high Xue, it is necessary to fight for strong seedlings in a timely manner. The combination of large bell mouths to prevent corn seedlings from removing weak strains will improve overall uniformity.
(VI) Water and Fertilizer Management Sweet corn production should pay attention to the application of potash fertilizer, increasing potassium can improve its nutritional quality and stalk sugar content. In the general condition of soil fertility, Mushi applies 7.5 kg of effective potassium, and general P and K fertilizers are applied as basic seed fertilizer at one time. Nitrogen fertilizer 30% for the base seed fertilizer, seedlings 3-4 leaves to recover 10% -20%, 7-8 leaves to start chasing 40% -50%, generally do not have to apply granules. Moisture management should pay attention to flood control at the seedling stage and drought protection in the middle and later stages.
(7) Compared with ordinary corn, the prevention and treatment of diseases, weeds and weeds must be done as early as possible in the early stage due to the slow seedlings of sweet corn and the grass shortage during the seedling stage. Insect pests of sweet corn are mainly seedling stage soil pests and ear stage corn borer, and 50% phoxim can be used for seed dressing or rooting. If corn is used to control pesticides, low-toxicity pesticides should be selected. For example, phoxim should be used for prevention and control during the trumpet period, so that pesticides can be used with caution, use less, and use pesticides earlier, which effectively controls pests without affecting the quality of sweet corn. Disease prevention and control is generally resolved through fitness cultivation and selection of disease-resistant varieties.
(8) The sweet corn harvested at the proper harvesting stage has the characteristics of being sweet, fragrant, crisp, tender and nutritious. Harvest time: Normal sweet corn is 17-23 days after silking. Supersweet corn is 20-28 days after spinning, and sweet corn is added 18-30 days after silking. For specific harvesting, a few ears can be peeled off first, and then the filaments and loquat leaves of the ear can be taken, and then the correct harvested ear can be properly grasped according to the color standard of the filaments and the loquat leaves. Generally speaking, the color of the spun silk in the same period is basically the same. Picking is usually done early in the morning so that it can be listed on the same day or shipped to a processing plant.
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