Eggplants are almost always grown from seedlings to avoid contact with low temperatures, which can inhibit their growth and development. Due to the frequent use of PE film in eggplant cultivation, the “drip irrigation” system is most commonly used.
Advantages of Container Seedling Cultivation:
Container-grown seedlings have a completely uniform vegetative space, allowing for consistent plant growth and uniform seedlings.
Ready-made substrates with good water-air relations, high water retention, and nutrient content sufficient for the complete development of seedlings are used for seedling cultivation. The substrates for seedling cultivation are sterilized and free from disease-causing organisms, pests, and viable weed seeds, which are present in all soils.
Transplanting is done with a substrate clump around the roots, which the well-developed seedlings have fully grown into. Transplanting with a substrate clump around the roots reduces transplant shock compared to bare-root transplants, allowing continuous growth. This also makes transplanting easier and faster, reducing the need for replanting. Such seedlings can be transplanted even if the soil moisture is not optimal, and transplanting can be done throughout the day, allowing for better utilization of existing planting equipment and planting on larger areas in optimal time.
Container-grown seedlings are ready for harvest earlier and generally yield higher than bare-root seedlings grown in beds.
Container cultivation is especially suitable for producing hybrid vegetables, where it is crucial to obtain quality seedlings from each seed due to the high cost of seeds.
For sowing in containers, ready-made substrates with good water-air relations, high water retention, and sufficient nutrient content for complete seedling development are used. The substrates are sterilized and free from disease-causing organisms, pests, and viable weed seeds.
Sowing can be done manually or with pneumatic seeders.
Eggplant seedlings can be pricked out after the first true leaf develops, which is why they are sown densely in beds or trays without partitions or in containers designed for pricking out. Such containers, typically 60×40 cm in size, have 400 – 450 cells (pots). The seedlings that sprout in these cells are pricked out with substrate clumps, ensuring 100% take and speeding up and simplifying the process compared to pricking out seedlings grown in beds or trays. Pricking out seedlings from small pots can be done mechanically. Pricking out, i.e., transplanting young seedlings, is done when the first true leaf appears. During pricking out, the seedlings from smaller pots are transplanted into larger ones (35 – 100 cm3). Weak or damaged plants are removed during pricking out, better utilizing the growing space as all cells are filled with plants. Pricked out plants are of higher quality, enter the generative phase earlier, and the fruits of such plants are generally larger, resulting in higher yields. Pricking out can be done manually or mechanically, and in both cases, the substrate must be optimally moist to prevent damage to the seedlings during extraction.
Microclimatic Conditions for Seedling Cultivation
To ensure faster seed germination, containers are placed in germination chambers where an optimal temperature (around 30°C) is maintained, with the air fully saturated with moisture using micro-sprayers that create a mist. The containers remain in the germination chambers for several days until the seeds germinate. They are then moved to heated protected spaces where a uniform optimal temperature is maintained day and night until the seeds fully germinate and the substrate moisture is maintained. After the young seedlings germinate and develop the first cotyledon leaves, the temperature in the protected space should be lowered to 20 – 25°C, with nighttime temperatures about 7°C lower than during the day, along with regular ventilation and substrate moistening. This temperature regime is maintained with ventilation and active airing until the seedlings develop 5 – 7 leaves and a visible flower bud, at which point they are ready for transplanting. High temperatures after germination can result in elongated and weak seedlings of poor quality and lower productivity.
If transplanting must be delayed due to unfavorable external conditions (low temperatures, overly wet soil, rain), seedlings can be stored for up to 2 weeks at a temperature of 1 – 2°C.
Seedling Cultivation and Care Before Transplanting
In protected spaces, containers are placed on raised platforms, achieved by placing bricks or stone blocks on the ground and laying iron mesh or wooden slats on top. The raised position allows for faster and better warming, and the air space under the containers prevents root growth through the openings at the bottom of the cells, allowing easier removal of seedlings during transplanting.
The substrate should be kept moderately moist throughout the entire seedling cultivation period. Due to the relatively small volume of the sowing cells in the containers, watering should be done in the morning, with moisture maintained during the day by misting. In the evening and overnight, it is preferable to keep the plants dry. Rainwater collected from the structures, water from private wells, or clean water from natural watercourses is best for watering. Direct watering with tap water is not ideal as it is usually much colder, which can negatively affect seedling development. Watering seedlings is done using automatic rain wings with sprayers that create very fine droplets, which do not damage young seedlings or compact the substrate. If watering is done manually, it is also necessary to use watering cans with fine rose nozzles. Automatic watering systems can also be used to apply foliar fertilizers like Fertina P, Profert Mara, Kristalon, and others as needed. Foliar feeding in seedling production is used when there is a noticeable loss of dark green color, often occurring if seedlings remain in containers for an extended period due to the inability to transplant at the optimal development stage.
Using quality treated seeds and growing in sterilized substrate generally negates the need for disease protection during container seedling cultivation. However, before transplanting, seedlings should be preventively treated with contact fungicides like mancozeb at a concentration of 0.2% or copper-based fungicides.
A week before the planned transplanting date, protected spaces should be fully opened to allow the seedlings to come into direct contact with sunlight and better adapt to the full spectrum of sunlight they will encounter after transplanting into the field. Before transplanting, the substrate should be moderately moist to facilitate the easy removal of seedlings with the substrate attached to the roots. If the substrate is too wet, it falls off the roots during planting, and if it is too dry, the plants will not take well in the field.
