Key Technical Points for Raising Seedlings of Sweet Peppers and Hot Peppers in Open-Field Cultivation

I. Variety Selection

For this cultivation method, it is advisable to choose varieties with strong growth vigor, disease resistance, and strong heat tolerance. For sweet peppers, such as Jiyan No. 6, Jiyan No. 4, and Zhongjiao No. 4; for hot peppers, such as Jize pepper, Wangdu pepper, etc.

II. Seedling Raising Must Be Adopted

For direct seeding, due to extensive management, it causes uneven seedling growth or missing plants and gaps in rows, a short growth period, and a transplanting time more than 40 days later than seedling raising and transplanting, with short plants and poor seedling quality. If a year with a major outbreak of viral disease occurs, the disease spreads, causing severe yield reduction or even total crop loss. When transplanting with the seedling-raising method, most of the seedlings already have flower buds, which can ensure that the plants grow effectively within the suitable season, that is, they quickly flower and set fruit, obtain a harvest, and before the hot summer season arrives, they can quickly close the rows, improve heat resistance, reduce the occurrence of diseases, and are especially helpful for suppressing viral disease. This allows earlier fruit setting, achieving the goals of early maturity, high yield, and disease resistance, and can save land and seeds.

III. Sowing

The sowing time is determined according to the local seedling-raising site, conditions, and transplanting period, as well as the standard that most seedlings have reached the stage of visible flower buds at transplanting. The seedling age is about 70 days. In the central and southern Hebei region, sowing is generally carried out in February in a solar greenhouse.

Seed disinfection before sowing: After soaking seeds in warm water at 55°C for 20-30 minutes, soak them in 1% copper sulfate for 5 minutes, which can prevent anthracnose, bacterial spot disease, and Phytophthora blight, then rinse them clean with clear water, then soak them in 2% sodium hydroxide or 10% trisodium phosphate for 15 minutes, which can inactivate the virus and prevent the occurrence of viral disease, rinse them clean with clear water, and soak them at room temperature for 4-8 hours. After soaking, remove the seeds, shake off the water, and place them at 25°C-30°C for germination acceleration, rinsing them once with clear water in the morning and evening, and sow after germination. In some places, germination acceleration is not carried out, and the soaked seeds can be rinsed and sown. During the germination acceleration process, in addition to paying attention to turning and rinsing the seeds, the wrapping should not be too tight. They will germinate in 4-5 days.

IV. Seedling Raising

Use ground-bed seedling raising. To reduce opportunities for disease transmission, do not prick out seedlings during the seedling stage, only thin them, and the seedling-raising area should be increased. For every 15 sq m of seedling bed, apply 100-150 kg of screened decomposed organic fertilizer and 1-1.5 kg of ternary compound fertilizer, mix evenly with the soil and level it, and water thoroughly before sowing. To prevent seedling-stage diseases, after the water seeps down, disinfect the seedling bed with 100-fold dilution of 50% carbendazim wettable powder, using 0.5 kg of solution per sq m, then mark rows at a spacing of 7 cm and sow in drills, cover with 1 cm of soil after sowing, and cover with plastic film on top.

Use plastic pot seedling raising. Preparation of nutrient soil: 50% fertile surface sandy loam that has not grown solanaceous fruit vegetables, plus 50% decomposed screened barnyard manure, and for every cubic meter add 0.5-1 kg of nitrogen-phosphorus-potassium compound fertilizer, 80-100 g of 50% carbendazim or 5 g of Luheng No. 1. After preparing the materials, mix the soil and fertilizer thoroughly and evenly, then fill the nutrient pots. Before sowing, water thoroughly, and sow directly with seeds that have already been germinated. After the cotyledons of the seedlings flatten out, thin them in time.

V. Seedling-Stage Management

Avoid seedlings being too crowded. Starting from the 1-leaf-1-heart stage, prick out and thin seedlings in time, and set plants at the 3-leaf-1-heart stage, with a hole spacing of 5 cm, to ensure sufficient nutrient area. At the 2-3 true leaf stage, the 3-4 true leaf stage, and 7-10 days before transplanting, spray a mixed fertilizer solution of 0.2% potassium dihydrogen phosphate + 0.1% urea + 0.2% zinc sulfate together with pesticide spraying, to promote flower bud differentiation and improve the disease resistance of the plants.

Temperature should be controlled in stages. After sowing, the soil temperature can be maintained at 28°C-30°C or even 32°C. When the seedlings arch through the soil, lower it to 27°C-28°C, and keeping the minimum nighttime soil temperature at 18°C-20°C can promote emergence. After the seedlings emerge, the maximum daytime air temperature should be maintained at 23°C-25°C, and at night it can gradually drop from 20°C to 15°C-17°C. 7-10 days before transplanting, gradually lower the temperature, and carry out low-temperature hardening of the seedlings; the daytime temperature can drop to 18°C-20°C and the nighttime temperature to 10°C-12°C.

Before sowing and at transplanting, the bottom water should be sufficient to maintain appropriate soil temperature. After transplanting, supplement water according to the seedlings, choosing a sunny day and doing it before noon. Special attention should be paid to not affecting soil temperature because of water supplementation in the later stage of seedling raising.

VI. Issues to Note in Seedling-Stage Management

1. Seedling legginess: Especially from the stage when the two cotyledons flatten out to the stage when true leaves break through the heart, this is the period most prone to legginess, and during this period temperature and water must be strictly controlled.

2. Seedling-stage diseases: The temperature must not be too high, and the soil moisture and air humidity must not be too high; otherwise, damping-off and Rhizoctonia rot are extremely likely to occur. Control measures: After 75% of the seedlings have emerged, spray 500-fold dilution of 50% carbendazim, or 500-fold dilution of 64% oxadixyl-mancozeb wettable powder, or 600-fold dilution of 75% chlorothalonil wettable powder to sterilize and prevent disease, and thereafter spray once every 7-10 days. Ventilate and exchange air in a timely manner to prevent excessive moisture and temperature in the seedling bed from inducing diseases.

3. Insect pests: When underground pests such as white grubs and mole crickets occur in large numbers in the seedling bed, they cause damage and lead to dead seedlings. Control measures: 1000-fold dilution of 80% dichlorvos emulsifiable concentrate can be used to pour onto the soil surface of the seedling bed to control white grubs; 50-fold dilution of 50% phoxim emulsifiable concentrate can be mixed with crushed, stir-fried fragrant soybean cake, wheat bran, etc. to make poison bait, and scattered on the soil surface of the seedling bed to kill mole crickets.

4. Wind-dried dead seedlings: Seedlings that have not undergone ventilation hardening are long kept in a space with relatively high humidity. When the seedling bed is ventilated, cold air directly convects, and when the covering is blown open by strong wind, the air temperature and humidity suddenly drop, causing the tender leaves to lose too much water and wilt. If the wilting lasts too long, the leaves cannot recover and finally become green and dry.

Control measures: When ventilating the seedling bed, open the ventilation opening on the leeward side, and the ventilation volume should go from small to large, so that the seedlings have a process of adaptation. In windy weather, pay attention to pressing the covering firmly to prevent it from being blown open.