Eggplant plants grown in greenhouses typically show strong growth and high yields during the first year. However, in the spring of the second year, their growth weakens significantly, and yield drops dramatically. This is a common issue known as premature aging of the plant's growth and development.
Several factors contribute to this early decline. First, seedlings are often raised from June to July when temperatures are high and humidity is significant. Without proper shading or cooling measures, the seedlings tend to become leggy, with weak root systems that struggle to absorb nutrients effectively. Second, applying excessive nitrogen-rich chemical fertilizers during the seedling stage can worsen this problem by promoting leafy growth at the expense of root development.
After planting, many growers apply large amounts of chemical fertilizers—often 100-150 kg of compound fertilizer as base fertilizer, with additional topdressing. Over the course of the first year, more than 300 kg of chemical fertilizer may be used. This over-fertilization can hinder root system development, leading to poor nutrient absorption.
In addition, shallow plowing techniques are commonly used in greenhouses, with some farmers only tilling 10 cm deep or less. This leads to soil compaction and poor structure, which is especially problematic for eggplants, a crop that requires deep, loose soil for healthy root growth. Shallow, compacted soil limits root expansion, further reducing the plant’s ability to take up water and nutrients.
Another factor is the use of double-dry pruning in greenhouses, aimed at increasing early yield. This method involves heavy pruning, which weakens the plant’s shoot and leaf growth. As a result, root development is also affected, leading to reduced absorption capacity later on. With increased height, the distance for water and nutrient transport becomes longer, negatively impacting overall growth and yield.
Mulching is another practice that can contribute to the issue. While it helps maintain a favorable surface environment, it can also prevent roots from growing deeply. This leads to shallow root systems that rely heavily on surface nutrients, which may become depleted over time, affecting the plant’s health in later stages.
To prevent premature decline, several measures can be taken. First, shading and cooling should be implemented during the seedling stage to avoid legginess and encourage strong root development. Fertilizer use should be minimized, and organic matter should be sufficient to meet the plant’s needs.
When planting, reduce the amount of chemical fertilizer used as base fertilizer—around 30-50 kg per acre. After planting, apply root-stimulating agents to promote healthy root growth. Before planting, consider using a soil conditioner to improve soil structure down to 30-50 cm, enhancing both root development and water retention.
During the second year, regular foliar feeding with essential nutrients like potassium, boron, calcium, magnesium, iron, and zinc can help address deficiencies. Spraying a plant growth regulator such as natural alfalfa Shuofeng 481 every 10-20 days can also enhance photosynthesis and vegetative growth, ensuring better long-term performance.
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