High-yield cultivation techniques for sweet corn: Is sweet corn genetically modified?

I. Isolation planting

Sweet corn should be planted in isolation from common corn or other types of corn to prevent cross-pollination. Spatial isolation and time isolation can be used, but spatial isolation is preferable. If spatial isolation is used, the distance should generally be more than 400 m in plain areas; if there are natural barriers such as woods, hills, buildings or roads, the isolation distance can be appropriately shortened. If time isolation is used, the sowing dates should differ by more than 30 days. In short, the principle is to prevent the pollen of the two types of corn from meeting.

II. Fine land preparation, adequate base fertilizer, shallow and careful sowing

Because sweet corn kernels contain little starch and have weak germination and soil-emergence ability, plots with loose soil, good fertility, good soil moisture and convenient irrigation and drainage should be chosen for planting. Where conditions permit, 1000-1500 kg of high-quality decomposed barnyard manure per mu, plus 15 kg of superphosphate, can be thoroughly mixed and composted, then applied before sowing. Sowing should be careful, with 3-4 seeds per hole, and the sowing depth should be slightly shallower than that of common corn, generally covering with about 4 cm of soil.

III. Sowing in stages

Sweet corn is grown to sell fresh young ears on the market or to supply factories for processing canned food, which is completely different from growing common corn. At the same time, sweet corn cannot be stored for long after harvest. Therefore, sweet corn should be sown in stages according to market demand and factory processing capacity, and early-, mid- and late-maturing varieties should be combined to improve economic returns.

IV. Reasonable dense planting

Planting density depends on variety characteristics, soil fertility, sowing date and planting method, while also taking into account the market quality of the ears. On generally medium-fertility soil, 4000 plants per mu is suitable; early-maturing varieties can be denser, and late-maturing varieties can be sparser.

V. Strengthen field management

1. Check and replant seedlings, thin and finalize seedlings

After emergence, seedlings should be checked and replanted promptly; when the seedlings have 3-4 leaves, thin them, and when they have 4-5 leaves, finalize them. The principle of thinning and finalizing is to remove the large and small ones and keep the middle ones, so as to ensure that the seedlings in the whole field are uniform and consistent.

2. Pay attention to topdressing and cultivate in time

Generally, about 1000 kg of organic fertilizer or farmyard manure per mu, 30 kg of urea (7.5 kg each at the seedling stage and jointing stage, and 15 kg at the large trumpet stage), and 5-7 kg of potassium chloride are applied as topdressing; potassium fertilizer and organic fertilizer or farmyard manure are applied as a one-time topdressing at the seedling stage. Topdressing should be applied in holes and deeply as much as possible, and soil should be covered promptly after application. After each topdressing, cultivate and weed, paying attention to leveling, breaking up clods and loosening the soil without damaging the seedlings.

3. Water in case of drought

In areas with irrigation conditions, water promptly at the seedling stage, large trumpet stage and grain-filling stage.

4. Control insect pests

For underground pests, 0.5 kg of phoxim plus 25-30 kg of fine sand per mu can be broadcast at the seedling stage; for corn borers, carbofuran granules can be broadcast at the heart-leaf stage or the late heart-leaf stage.

VI. Timely detasseling

Timely detasseling is a key cultivation technique for ensuring high yield and good quality in sweet corn. But timely detasseling is the key to success; if detasseling is too early, the top leaves are easily pulled out; if too late, too much nutrition is consumed and the significance of detasseling is lost. For harvesting baby corn, detasseling should be done when the tassel extends beyond the top leaves but has not yet shed pollen; for harvesting young sweet corn ears, detasseling should be done 2-3 days after the tassel sheds pollen.

VII. Timely harvest

The harvest time of sweet corn greatly affects its market quality and nutritional quality. If harvested too early, the kernels contain fewer contents; if harvested too late, the pericarp becomes hard and fibrous, and the unique flavor of sweet corn is lost. Generally speaking, the suitable harvest time is 20-23 days after pollination of the ear; if the purpose is canning, it can be harvested 1-2 days earlier, and if the main purpose is selling fresh ears, it can be harvested 1-2 days later.

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The cultivation history of sweet corn is very long, and purple corn and multicolored kernel corn are also the result of changes in corn's own genes, which has nothing to do with transgenic technology itself. Moreover, China has not yet approved commercial cultivation of this type of genetically modified corn, so it is very unlikely that genetically modified sweet corn can be bought on the market.