In protected cucumber cultivation, a common issue known as "flower topping" or "melon topping" may occur. This phenomenon is characterized by the stagnation of plant growth, with the growing tip becoming compact and unresponsive. The top leaves become densely packed, and within a short time, clusters of male and female flowers develop, causing the plant to seal itself at the top—hence the term "flower topping." If a small fruit appears at the top, it is referred to as "melon topping." At this stage, the plant stops producing new leaves and shoots, while the middle and lower parts remain dark green, with wrinkled and swollen leaf surfaces. If left untreated, the plant may die quickly, leading to early harvests and significant economic losses.
The primary cause of "flower topping" is low temperatures in the greenhouse, especially at night, along with large temperature fluctuations between day and night. After the emergence of cucumber seedlings, flower bud differentiation begins when the true leaves appear. By the time the plant has 3–4 true leaves, more than 20 leaf and flower primordia are already differentiated at the growing point. These primordia will eventually develop into leaves and flowers. Under conditions of large temperature differences and short daylight hours, the formation of female flowers is favored. However, excessive female flower development consumes more nutrients, which can inhibit vegetative growth and lead to "flower topping."
Other contributing factors include low soil temperature, overly dry or wet soil, the use of undecomposed manure, or an overuse of nitrogen fertilizer, all of which can impair root development and reduce the plant’s ability to absorb nutrients. Additionally, many farmers use plant growth regulators like gibberellins or Zenggualing to boost yields. These substances increase endogenous hormones in the plant, directing nutrients toward the pistil and promoting the formation of multiple female flowers. As a result, male flowers may degenerate, leading to plants that only have old leaves and no new growth.
To prevent and manage "flower topping," it's essential to raise seedlings in advance and maintain a minimum nighttime temperature of 13°C during the flower bud differentiation stage, with daytime temperatures above 23°C. Proper lighting is also important—greenhouse coverings should be managed to maximize sunlight exposure, and supplemental lighting may be used if needed. Soil should be loosened regularly after planting to improve aeration, increase soil temperature, and promote root development. Adequate watering is crucial, ensuring sufficient water for both planting and seedling stages, and adjusting irrigation based on weather, plant growth, and location within the greenhouse.
Fertilization must be balanced and fully decomposed to avoid root damage. For plants showing signs of "flower topping," it's important to harvest mature fruits promptly and thin out excess female flowers or melons. Stronger plants should retain 1–2 fruits, while weaker ones should have all their fruits removed to redirect nutrients back to vegetative growth. Spraying cytokinin (diluted 300–400 times) every seven days can stimulate lateral bud growth and help restore healthy plant development.
Natural Food Colorants
what is natural food color?
Natural food coloring refers to pigments extracted or prepared from plants, animals, microorganisms or other natural sources for coloring food. These pigments are naturally produced due to biochemical reactions in living organisms and do not contain synthetic chemical components.
Natural food colors can be divided into the following categories according to their source:
1. Plant pigments: This is the most common source of natural food pigments, including pigments derived from a variety of fruits, vegetables, flowers, and plant roots. For example, red beets can provide red pigments, carrots can provide orange pigments, turmeric can provide yellow pigments, and blueberries and purple potatoes can provide purple and blue pigments.
2. Animal pigments: These pigments are rare and usually come from the tissues or excretions of certain animals. For example, cochineal is a red pigment derived from the cochineal insects that live on certain cacti.
3. Microbial pigments: Some microorganisms, such as monascus, can produce specific pigments, such as monascus red pigments.
4. Mineral pigments: Although less used, certain inorganic minerals can also be used as natural food pigments, such as titanium dioxide (white) and iron oxide (red, yellow and black). However, due to possible toxicity issues with some mineral pigments, their use is often severely restricted or banned.
Natural food colors are generally considered safer and healthier than synthetic colors due to their nature. However, their color stability, heat resistance, light resistance, and interaction with other food ingredients may not be as good as synthetic pigments, so their application in the food industry sometimes presents some challenges. At the same time, the extraction and processing of natural pigments can also affect their cost and sustainability. Nevertheless, as consumer concerns about food safety and health increase, the demand for natural food coloring is growing.
Natural Food Colorants,Natural Food Pigments, natural food color
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