Key Points for Maize Seedling Management

Corn is an annual herbaceous plant belonging to the genus Zea in the grass family, and it is an important food and feed crop. During corn cultivation, effective management throughout the various growth stages is crucial for enhancing yield and quality, particularly during the seedling stage.

The seedling stage spans from emergence to the jointing phase. The primary objectives of seedling-stage management are to ensure uniform, complete, well‑spaced, and vigorous stands. Key management practices include checking fields and replanting missing seedlings, thinning to establish an even stand, and performing intertillage and weeding.

1. Field Inspection and Seedling Replacement: Due to factors such as seed quality and soil moisture, sown corn may exhibit varying degrees of missing seedlings or broken rows, which can significantly reduce yield. After emergence, regularly inspect the fields; if any gaps are found, promptly carry out replanting or transplanting.

2. Timely thinning and final planting: Thinning should be done early, ideally before the seedlings have fully established their roots—typically when they have 3–4 leaves. The guiding principles are: remove weak seedlings and retain strong ones; eliminate杂seedlings and keep uniform, uniformly colored plants; and discard diseased seedlings, leaving only healthy ones. If thinning is delayed, the plants may become overly crowded, shading one another and competing for water and nutrients, which can stunt the development of the primary root system and, in turn, hinder above‑ground growth. Final planting is generally carried out when the plants have 5–6 leaves, with spacing adjusted according to the variety and soil fertility.

The timing of final thinning should be as early as possible. In areas and fields where underground pests are severe, increase the number of thinning operations and delay final thinning slightly, but ensure it is completed no later than when the plants have six leaves. When thinning, be sure to pull out the seedlings with their roots intact to prevent the emergence of “stubborn” regrowth. During final thinning, follow the principle of “four removals and four retainments”: remove weak seedlings and retain strong ones; remove uneven-sized seedlings and retain uniform ones; remove diseased seedlings and retain healthy ones; and remove mixed‑type seedlings and retain pure‑line seedlings. Additionally, remember to carry out thinning on clear, sunny days.

3. Intermediate Cultivation and Weeding: Intermediate cultivation loosens the soil, promotes root development, and regulates above‑ground growth, thereby enhancing soil microbial activity. It also helps control weeds, reduces soil nutrient depletion, and improves the nutritional conditions for corn. By eliminating weeds and preventing weed competition, it minimizes the consumption of nutrients and water and limits the spread of pests and diseases, creating a favorable environment for corn growth. During the seedling stage, three rounds of intermediate cultivation are generally recommended: the first, before thinning, when the seedlings have 4–5 leaves, at a depth of 3–5 cm; the second, after thinning, when the seedlings reach about 30 cm in height, at a depth of 7–8 cm; and the third, just before the jointing stage, at a depth of 5–6 cm. The principle to follow is: “Do not mound soil on the first pass; mound lightly on the second; and form wide ridges on the third.”