As the protected vegetables enter their peak fruiting period, they also experience a high demand for water and nutrients. Therefore, it is essential to fully understand the nutrient requirements of these crops during this critical phase in order to apply fertilizers in a scientific and rational manner.
During the peak growth stage of fruits, the absorption ratio of nitrogen (N), phosphorus (P), and potassium (K) differs from the early growth stages. At this time, the crop requires more potassium, a stable amount of phosphorus, and an increased but relatively lower level of nitrogen compared to potassium. However, many farmers still hold misconceptions about fertilization. Through conversations with local growers, we found that they often believe that phosphate fertilizer, urea, and ammonium bicarbonate are suitable for fruit development, and that applying more fertilizer will always lead to higher yields. This has resulted in excessive nitrogen and phosphorus application, while potassium levels remain insufficient.
Excessive nitrogen can lead to larger leaf areas and darker green foliage. In severe cases, leaves may become thick, hard, and twisted, and fruit production may decrease or become misshapen. Over-application of phosphate fertilizer can cause symptoms like chlorosis due to deficiencies in zinc, iron, and magnesium, as phosphate can bind with these elements in the soil, reducing their availability.
A lack of potassium can result in scorching along the edges of older leaves, increased fruit cracking, reduced sugar content, poor flavor, and premature plant decline. To avoid these issues, it's recommended to apply fertilizers in small amounts and focus on potassium supply. If trace elements need to be supplemented, foliar sprays are an effective method.
In addition, as temperatures inside the greenhouse rise, some problems such as tomato umbilical rot or the top of cucumber plants turning dry and brown may appear. These symptoms are typically caused by calcium deficiency. When the temperature increases too quickly, it can hinder the plant’s ability to absorb water, disrupting calcium transport and leading to a deficiency at the growing tips. To address this, it’s important to regulate the greenhouse temperature, avoid drastic fluctuations, ensure timely watering, and apply calcium foliar sprays.
As outdoor temperatures increase, the population of viral vectors such as aphids and whiteflies also rises. It is crucial to implement pest control measures to reduce the spread of viral diseases. Installing insect nets is an effective and cost-efficient solution. All vents in the greenhouse should be covered with colorless insect nets. A disinfectant tank should be placed at the entrance, with lime used for foot disinfection inside. A 10% trisodium phosphate or 0.1% potassium permanganate solution should be prepared for hand disinfection before entering the greenhouse. For aphid control, spraying with 25% AKTA diluted at 7,500–10,000 times is recommended. These practices can significantly reduce the risk of viral disease outbreaks.
Author: Tense
Source: Rural Newspaper
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