Uneven tomato coloration reason

Uneven tomato coloration-specifically the appearance of distinct green patches on the fruit's shoulders (near the stem) while the bottom has already begun to turn red-is a classic example of "green shoulder," a condition that is indeed a form of uneven ripening.

Analysis of primary causes: 1. Unsuitable temperature (most common cause): Tomato color change involves the breakdown of chlorophyll and the synthesis of red pigments; the optimal temperature range is 19°C–30°C. Excessively high daytime temperatures (above 32°C) inhibit the synthesis of lycopene, causing chlorophyll at the fruit's "shoulder" to persist and resulting in a green shoulder.

2. Excessive nitrogen and insufficient potassium: During the fruiting stage, an over-application of nitrogen promotes excessive vegetative growth, causing the foliage to compete with the fruit for nutrients while simultaneously inhibiting lycopene synthesis; conversely, potassium is crucial for fruit expansion and color development, and a deficiency easily leads to the occurrence of "green shoulders."

3. Insufficient light or excessive foliage density: If the plant's foliage is overly dense, or if old or diseased leaves surrounding the fruit are not removed in a timely manner, the fruit receives inadequate light and photosynthesis is reduced; this interferes with normal pigment formation.

4. Improper moisture management: Soil fluctuating between dry and wet states, or excessive air humidity within the greenhouse, can impair the root system's nutrient absorption, thereby affecting the normal color change of the fruit.

Given the current situation, you can try the following measures to improve the coloration of subsequent fruit: * Scientifically manage temperature: For greenhouse cultivation, ensure increased ventilation and cooling during the day; aim to keep the temperature around 28°C and maintain an appropriate temperature difference.

 Reduce nitrogen and increase potassium: From now on, strictly control nitrogen fertilizer application and prioritize potassium supplementation during the color-change stage. Applying high-potassium water-soluble fertilizer via irrigation or spraying potassium dihydrogen phosphate on the foliage is highly effective in promoting uniform red coloration of the fruit.

Supplementing with secondary and trace elements: Appropriately supplementing trace elements such as boron and calcium also helps improve the internal environment of the fruit and the quality of color development.

Water management: Maintain a wet-dry cycle in the soil; avoid heavy flood irrigation; instead, advocate for frequent, light watering or drip irrigation to preserve soil aeration.

Prune and defoliate judiciously: While ensuring the plant canopy does not become overly dense, selectively remove old or diseased leaves that shade the fruit (taking care not to remove too many at once, so as not to impair the plant's overall photosynthesis) to allow the fruit to receive ample sunlight.