Control of common physiological diseases of tomato fruits
Physiological diseases in tomato fruits are primarily caused by unfavorable environmental conditions. Once the environment stabilizes, these diseases usually stop progressing and may even reverse. Common causes include improper temperature, insufficient or excessive light, water imbalance, nutrient deficiencies, and incorrect agricultural practices.
1. Green Back Fruit
Symptoms: After the fruit turns red, a green area or patch appears near the shoulder or stem end, remaining unripe. The affected part is hard, sour, and has poor flavor. This condition reduces the fruit's quality and marketability.
Cause: Overuse of nitrogen fertilizer, excessive plant growth, and deficiencies in potassium and boron are key factors. Dry soil conditions can also contribute to this issue.
Control Measures: During the fruit enlargement stage, apply potassium fertilizers and spray micro-nutrient solutions containing potassium and boron to improve fruit quality and reduce the occurrence of green back fruit.
2. Brown Fruit
Symptoms: When the fruit ripens, it takes on a brownish hue instead of a bright red color. The surface becomes dull, with reduced shine and commercial value. The fruit may appear discolored and less appealing.
Cause: Low temperatures and insufficient light during ripening are primary causes. Temperatures below 24°C delay lycopene formation, leading to brown discoloration. Excessive nitrogen, lack of potassium or boron, and continuous cropping in greenhouse environments can also trigger this problem.
Control Methods: Maintain proper fruit ripening conditions by avoiding extreme dryness or wetness. Limit nitrogen fertilizer use to prevent excessive vegetative growth and ensure balanced nutrition for the plants.
3. Umbilical Rot Fruit
Symptoms: Initially, a dark green or gray water-soaked spot appears at the top (umbilicus) of young fruits. It quickly turns black, causing the flesh to lose moisture and become sunken. In some cases, concentric rings may form, and the fruit may rot if humidity is high.
Cause: Calcium deficiency is the main cause. Factors contributing to this include irregular watering, excessive nitrogen or potassium, high temperatures, and the use of growth regulators during fruit development.
Prevention: Avoid over-fertilizing with nitrogen and potassium. Ensure consistent irrigation to prevent soil from drying out. From the fruiting stage onward, spray calcium chloride solution (0.1–0.3%) every seven days, or use calcium-based fertilizers like Green Fenway No.3 for better results.
4. Sunburn Fruit
Symptoms: The fruit develops large white, chlorotic spots that become transparent and leathery. Later, the skin shrinks, hardens, and turns yellow, with wrinkling and necrosis. The flesh may turn into brown lumps, reducing fruit quality.
Cause: Direct exposure to intense sunlight at high temperatures causes sunburn. This is common in areas with no adequate leaf cover or shading.
Control Measures: Plant tomatoes at an appropriate density, prune moderately, and position inflorescences on the inner side of supports where they are naturally shaded by leaves. Leave two leaves on the last ear when topping to provide shade. Ensure good ventilation, lower temperatures, and use shade nets to protect the fruit from direct sunlight.
Medicine Peptides and protein drugs are emerging. There are now 35 important therapeutics on the market, and the development of biotechnology and biopharmaceutical companies is becoming increasingly global. Biotechnology drug research focuses on the application of DNA recombinant technology to develop peptides, proteins, enzymes, hormones, vaccines, cell growth factors and monoclonal antibodies that can be used in clinical applications. According to Parexl's Pharmaceutical R&D Statistical Source Book, there are currently 723 biotech drugs under FDA review (including phase â…° to iii clinical and FDA evaluation), 700 drugs are in early stage (research and preclinical). More than 200 additional drugs are in the final stage of approval (Phase iii clinical and FDA evaluation). The basic dosage form of biotech drugs is lyophilized. Although the efficacy of conventional preparations has long been clinically proven, they need to be injected frequently for a long time due to their short half-life, which is difficult to accept from the perspective of psychological and economic burden on patients. To this end, scholars around the world mainly from two aspects to study and develop convenient and reasonable drug delivery approaches and new preparations: (1) embedment agent and sustained-release injection. â‘¡ Non-injectable dosage forms, such as respiratory inhalation, rectal administration, nasal administration, oral administration and transdermal administration, etc. Injectable preparations of sustained-release biotechnological drugs are new dosage forms with promising applications. Some of them, such as microsphere injections of luteinizing hormone releasing hormone (LHRH) analogues which can be sustained-release for 1 to 3 months, have been on the market. This paper focuses on this kind of preparations.Main types of peptides and protein drug sustained-release preparations The research and development of peptides and protein drug sustained-release preparations can be divided into two types, namely, embedment agent and microsphere injection, from the perspective of development process and dosage form. The shape of the implant is a hollow micro-fine rod, one end is closed, the other end is open, and the rod material is non-biodegradable polymer such as ptfe. The lumen was filled with a mixture of drugs and silica gel (silastic, polydimethylsiloxane). The implant is embedded under the skin, and the drug is released slowly through the opening of silica gel matrix. The American Physicians' Handbook (PDR) contains a product called Norplant? Levo-18 ethyl norethinnes, used in family planning. The preparation, each with a diameter of 2.4 mm and a length of 34 mm, is surgically implanted in the inner side of the patient's upper arm with 6 thin rods. The drug can be released in the body in zero-grade mode for up to 5 years, and then removed by surgery after release,1.1.2 Micro-osmotic pump embedding agent The United States Alza company in the 1970s developed an embedding agent shaped like a capsule, which is embedded in the skin or other parts. The body fluid can penetrate through the shell, dissolve the interlayer electrolytic layer, make the volume expansion of the interlayer pressure to the plastic inner cavity, and promote the drug solution from the opening of the fixed speed release. Many biomolecular drugs, such as insulin, heparin and nerve growth factor, have been reported as model drugs in vivo and in vitro. Implants have positive significance for the treatment of chronic patients who need long-term medication, but it has the following defects: â‘ must be surgically implanted. â‘¡ The skeleton material of the preparation is non-biodegradable polymer, which needs to be removed by surgery after release. â‘¢ The preparation has irritation and discomfort in local tissues. Evaluation methods for polypeptide protein drugs: 1. Liquid chromatography 2. Spectroscopic 3. Solvent-based versions are easy to use, but need to be kept at low temperatures (2-8 degrees Celsius).
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