Five Key Measures for Successful Plug Tray Substrate Seedling Raising

Plug tray substrate seedling raising is a major technological innovation in vegetable seedling production. It overcomes the drawbacks of traditional nutrient pot seedling raising, such as lower seedling survival rates, difficult disease control, high cost input, and large bed space occupation, and is warmly welcomed by the majority of vegetable growers.

When it comes to plug tray substrate seedling raising, Song Chunming of Guanlu Village, Daotian Town, Shouguang City, is highly experienced. Facing the high-temperature conditions of summer, Song Chunming said: “To cultivate uniform and sturdy seedlings, the following five steps must be carried out well.”

1. Select plug trays with suitable cell sizes and substrates according to the specific seedlings.

The choice of plug tray should be determined based on factors such as the type of vegetable being grown and the size of the seedlings. For example, 72-cell or 105-cell trays are mostly used for sweet peppers, 105-cell trays are mostly used for tomatoes, and 50-cell trays are mostly used for grafted seedlings. Before sowing, the plug trays should first be disinfected. They can be soaked in hymexazol solution, or disinfected with potassium permanganate solution. This is especially important for old plug trays, which require thorough disinfection measures.

The selection of substrate is an important step in plug tray substrate seedling raising. In production, many seedling factories and vegetable growers experience problems such as slow seedling growth and yellowing leaves precisely because of improper substrate selection.

Substrate selection should be based on the requirements of the seedling root systems of the melon and vegetable crops being grown for pH value, nutrients, and other factors. A suitable substrate should be chosen; for example, imported substrates can be used, or Luqing seedling substrate, among others. The substrate should also be disinfected before being loaded into the plug trays. It can be treated with carbendazim, or mixed in a certain proportion with Jikangjun 968 Miaobao, using beneficial microorganisms to suppress harmful ones and protect normal seedling growth.

2. Water thoroughly to ensure full emergence after sowing.

Before sowing, spray enough bottom water in one application to thoroughly soak the substrate. When water begins to appear at the bottom layer, the requirement for sowing, germination, and emergence is met. At the same time, pesticides can be applied along with watering based on seedling-stage diseases. If there is too much bottom water, it will lower the bed temperature; if there is insufficient bottom water, it will increase the difficulty of supplementary watering to promote full emergence. After sowing, cover the seeds with substrate according to the required covering depth for different crops, then cover with plastic film on top to retain heat and moisture, promoting uniform, full, and even seedling emergence.

3. Remove the film promptly to prevent scalding the seedlings.

When the emergence rate of plug tray seedlings reaches more than 50%, the plastic film should be removed promptly to prevent high temperature and water shortage from scorching the seedlings during emergence, thereby helping to ensure full stands and promote sturdy seedlings.

4. Strengthen management and improve the seedling growing environment.

Although plug tray substrate seedling raising is simple and feasible, during the high-temperature and rainy summer season, using “two nets and one film” coverage for seedling raising remains the focus of management during this period.

The two nets refer to a shade net and an insect-proof net; the one film refers to plastic film. The shade net serves to block light and lower temperature, the insect-proof net serves to prevent pests from entering, and the plastic film serves to protect against rain. It should be emphasized here that the use of shade nets must be scientific and reasonable. After the seeds emerge, they must not be covered for extended periods, so as to avoid poor seedling growth.

5. Supplement water and fertilizer appropriately to achieve full-age sturdy seedlings for transplanting.

Plug tray seedling raising requires timely water supplementation. Generally, when the substrate surface turns white, water supplementation is needed. At the same time, based on the nutrient content of the substrate and the growth condition of the seedlings, foliar spraying is mostly used to appropriately supplement nutrients along with watering. Pest and disease control is the same as for normal seedling raising. Based on seedling age and transplanting time, reasonably determine the appropriate sowing date, and carry out scientific regulation according to the leaf age standard for transplanting, preventing excessive fertilizer use from causing excessive seedling growth, to ensure sturdy seedlings of the appropriate age are transplanted.