Detailed Explanation of Eggplant Cultivation Techniques and Management Methods
Eggplant Seedling Raising
1. Determination of seedling raising site and sowing time: In Shanxi Province, winter-spring crop eggplants in solar greenhouses are generally sown in mid-October. In order to bring them to market earlier, eggplants need to be raised into large seedlings with a longer seedling age, usually 90-100 days.
2. Seed soaking and sprouting: First put the seeds into 55°C warm water, using an amount of water 5-6 times the volume of the seeds, stirring constantly, and maintaining the 55°C water temperature for 10-15 minutes, then soak the seeds in the water as it naturally cools for 8-12 hours. The eggplant seed coat is thick and absorbs water with difficulty; if the seeds have not been fully fermented, they are even harder to germinate. First wash them with a 0.2-0.5% alkaline solution, and rub and wash repeatedly with clean water until the seed coat is clean and free of mucus, then soak the seeds. Alternatively, first soak them in a 1% potassium permanganate solution for 30 minutes before soaking the seeds. During soaking, change the water once every 5-8 hours. When the seeds have fully absorbed water, rinse them clean with clean water and scoop them out, wrap them well in multiple layers of wet cloth or burlap, shake off the water, place them in a container, and put them in a warm place to sprout. The suitable temperature for eggplant germination is 25-35°C. Because seed maturity varies, the temperature and oxygen in the sprouting bag are uneven, which causes uneven seed germination. Therefore, it is best to use alternating temperature sprouting: in one day, 30°C for 8 hours and 20°C for 16 hours. After 5-6 days, 75% of the seeds will have sprouted white, and the sprouts will be neat and uniform. During sprouting, frequently turn the seed bundle to help with gas exchange through the seed coat.
3. Sowing: Eggplant growth requires relatively high temperatures, so in greenhouses it is best to sow in sowing boxes; this method allows them to be moved freely and makes it easier to adjust temperature and light. First spread a 3 cm thick layer of nutrient soil in the sowing box; water thoroughly the first time, and after the water has seeped down, sprinkle a layer of fine soil, then broadcast or drill the seeds. After sowing, cover with 1 cm of fine soil, then cover with plastic film, and remove it promptly when the seeds emerge.
4. Seedling stage management: After sowing, the room temperature should be 25-30°C with even light, and seedlings emerge after 5-6 days. After 80% of the young sprouts have emerged, lower the room temperature to 20-25°C during the day and 20°C at night; ventilate appropriately when it exceeds 28°C, but the ventilation amount must not be too large or too sudden. Stop ventilation when the room temperature drops to about 20°C. When the cotyledons have unfolded and the first true leaf is tipping out, the room temperature can be raised to 25-27°C during the day, 16-18°C at night, and the soil temperature to 18-20°C, to promote smooth true leaf growth until transplanting. Under conditions of sufficient soil moisture, eggplant grows and develops well; when moisture is insufficient, flower bud differentiation is delayed, the fruiting period is postponed, and early yield declines. Before sowing and transplanting eggplants, the bottom water must be watered sufficiently; afterward, according to seedling growth, appropriately supplement water to meet their growth needs. Eggplant seedlings have strict requirements for light conditions; sufficient light not only benefits flower bud differentiation but also allows seedling growth and development to proceed smoothly. When light is insufficient, flower bud differentiation is delayed, seedlings become leggy, and deformed flowers appear, directly affecting yield formation. To improve light conditions, the seedling box can be tilted toward the south to capture light. Increasing the area of the nutrient paper bags used for transplanting and arranging them at a reasonable density also helps improve light conditions.
5. Transplanting: Eggplant roots have poor regeneration ability and difficulty producing new roots, so generally seedlings are transplanted only once into nutrient paper bags when they have 2-3 true leaves and flower bud differentiation has not yet begun. Using nutrient paper bags for seedling raising is a relatively good method for protecting eggplant roots; just note that when preparing the nutrient soil, add somewhat more nitrogen fertilizer. Water the nutrient paper bags sufficiently 1-2 days before transplanting, judging by moisture visible at the bottom of the paper bags. When transplanting, shake the seedlings out of the already loose soil in the sowing box, and plant them into the nutrient paper bags along the direction of the roots, without bending them. The standard for strong seedlings when eggplants are planted out is: seedling height 18-20 cm, 6-7 leaves, more than 70% of the first eggplant flower showing buds, thick purple stems, and well-developed roots.
Planting Out
1. Before planting out, apply 5000 kg of base fertilizer per mu, deep plow and level, then make high ridges 60-65 cm wide and 15 cm high, then open two shallow furrows on the ridges and water the bottom water sufficiently. After the water seeps down, plant according to a spacing of 30-40 cm between plants, then take soil from between the two shallow furrows on the high ridge to close the furrows. The planting depth should be such that the seedling block is level with the ground surface. Plant 3000-4000 seedlings per mu.
2. The planting time should be chosen during the warming period just after a cold wave has passed. According to the patterns of northern climate conditions, choosing this planting period can ensure that the seedlings maintain clear, fine weather for 3-5 days after planting out, which helps them recover. On the day of planting out, it should be done during the high-temperature period from 10:00 to 14:00.
Management
1. After eggplants are planted out, the biggest difficulty is insufficient soil temperature, so during the low-temperature season after planting out, cold protection and heat preservation must be strengthened. For 7-10 days after planting out, keep the room temperature above 30°C, thereby raising soil temperature, supplementing night temperature, and helping the seedlings recover as quickly as possible. Also try to keep the soil temperature stable at 16-18°C. After the seedling recovery period, the plants begin normal growth, and every day attention must be paid to removing covers to let in light; insufficient light can very easily cause flower drop. After seedling recovery, the first eggplant flower opens and the plant enters the fruiting period. At this time, attention should be paid to regulating the balance between vegetative growth and reproductive growth, lowering the room temperature to 25-30°C during the day and 15-17°C at night. This allows the eggplant to flower and fruit while also growing lush branches and leaves. When the room temperature exceeds 25°C, begin appropriate ventilation to remove excess moisture from the greenhouse, increase carbon dioxide content, raise light intensity, and reduce flower drop. Even on cloudy days, persist with appropriate ventilation, but pay extra attention to the ventilation amount and duration.
2. After eggplants are planted out and given the seedling recovery water, do not water again until the first eggplant flowers open; water and fertilize only after the first eggplants have generally grown to 3 cm in size. The first fertilizer and water application can be somewhat larger: apply 10-20 kg of ammonium sulfate per mu or 1000 kg of diluted manure. When the second eggplant fruit begins to swell, give the second fertilizer and water application; afterward, apply fertilizer and water once every 10-15 days. In the mid-to-late fruiting period, water and fertilizer must not be lacking.
3. Eggplant is a light-loving crop, but in winter-spring cultivation in solar greenhouses, natural light can hardly meet its needs, causing plants to become leggy, producing short-stigma flowers, and resulting in deformed fruit. Therefore, in addition to cleaning the greenhouse roof every day, reflective curtains should also be hung to reduce the light gap in the middle and rear parts of the greenhouse and increase light intensity.
4. 2-3 days before the eggplant flowers open, use 25-30 ppm 2,4-4 to smear the fruit stalk, or spray the flowers; treat each flower only once, do not repeat, and do not spill the solution onto the leaves.
5. Prune in a timely manner to improve ventilation and light conditions. After the first eggplant fruit swells, remove the side branches sprouting below the first eggplant and the lower old leaves; the axillary buds below the second fruit (the second eggplant) must also be removed.
6. During the peak fruiting period, appropriately increase the amount of fertilizer and water; generally water once every 7-10 days, alternating chemical fertilizer and organic fertilizer. At the same time, increase ventilation to meet the needs of photosynthesis and promote fruit ripening.
Harvesting
When the eggplant has fully swollen and the fruit is purple and glossy, harvest it early to increase early yield and raise output value. When harvesting, it is best to cut it off at the fruit stalk to reduce bruising.