Why do tomato flowers turn yellow before they even open?

September is the critical period for flowering and fruit setting of autumn-delayed tomatoes. At this time there are fewer diseases and the temperature is suitable, making it the most suitable period of the year for vegetable growth. However, many vegetable growers report that the tomatoes in their greenhouses turn yellow and drop before they even flower. What is going on here? Let's take a look together.

1. Poor weather during the seedling stage

For autumn-delayed tomatoes, the seedling raising period is concentrated in July, and this summer had a lot of rain and many cloudy days, which made the overall light during the tomato seedling stage relatively weak. High temperature and weak light inevitably lead to thin and weak tomato seedlings. Therefore, this year's tomato seedlings are generally weak, with thin and weak seedlings and poor stress resistance. After transplanting, there are few cooling measures in the greenhouse, and the greenhouse temperature is high, so many seedlings are scalded, triggering problems such as damping-off disease. Moreover, the appearance of a harsh environment will induce vegetables to produce substances such as ethylene, which will accelerate the aging and dropping of leaves, flowers and so on, so tomatoes show yellowing before they even flower.

2. Poor flower bud differentiation

Poor flower bud differentiation is also one of the main reasons why flowers turn yellow and drop before opening. A high-temperature and weak-light environment will weaken photosynthesis, reduce nutrient accumulation, cause the plant to become thin and weak, lead to flower bud abortion, and result in flower drop. Water and fertilizer conditions have a great influence on flower bud differentiation, and many elements play indispensable roles in flower bud differentiation. However, many farmers apply large amounts of chemical fertilizer, which leads to soil nutrient imbalance, increases soil salinization, and affects the roots' absorption of other elements. In addition, the large-scale irrational application of hormones can easily cause hormone imbalance within the plant, leading to disordered plant growth.

3. Improper fertilization

⟦NL>Base fertilizer is a key means of improving the soil. Many farmers use farmyard manure and compound fertilizer as base fertilizer, focusing on fertilizers such as nitrogen, phosphorus and potassium, but they supplement very little of the medium and trace elements such as calcium, magnesium, iron, zinc, boron and molybdenum. However, these trace elements are closely related to flower bud differentiation in plants. The root system is weak at the seedling stage, and applying large amounts of chemical fertilizer will make it difficult for the soil's trace elements to be absorbed, thereby affecting flower bud differentiation and even causing flower bud abortion and flower drop. Generally speaking, in addition to applying decomposed organic fertilizer, trace elements also need to be properly combined and turned into the soil together with the organic fertilizer to ensure balanced soil nutrients.

  The above is an introduction to what is going on when tomato flowers turn yellow before opening. I hope it can help you. If you want to learn more related knowledge, please keep following us.