Tomato cracking is a common yet complex issue faced by growers across varied climates, particularly in regions with pronounced temperature shifts. According to Umair Anwar, temperature fluctuations play a big role in triggering this physiological disorder in tomatoes.
"Cracking in tomatoes is largely a result of rapid changes in day and night temperatures," he says. During the daytime, when temperatures range between 25–35°C, photosynthesis is at its peak. "This results in an accumulation of sugars and increased turgor pressure within the fruit. At night, temperatures often drop to 10–20°C, slowing down transpiration and water uptake, yet the fruit continues to absorb water due to osmotic gradients. This internal water movement builds pressure, often beyond what the tomato's skin can handle."
Umair is an agricultural engineer working as an operational agronomist at Global Farms in the UAE. He is originally from Pakistan and has experience in both indoor and outdoor farming, with a focus on hydroponics and soil-based agricultural practices. "My expertise lies in crop production and crop protection, and I have previously worked in both Oman and Saudi Arabia."
Types of cracks and how they form
He explains that the tomato's outer layers—its cuticle and epidermis—lose elasticity under thermal stress. "This means that when internal pressure spikes, the skin becomes prone to rupture," he notes. The outcome manifests in two primary forms of cracking: radial cracks and concentric cracks.
"Radial cracks are vertical splits that extend from the stem end downwards. They usually happen when there's a sudden influx of water, like after heavy irrigation or rainfall following a dry spell." On the other hand, concentric cracks form circular patterns around the fruit's shoulder, often caused by the stress of daily expansion and contraction due to inconsistent temperatures.
© Umair Anwar
The mechanisms at work
Anwar outlines the mechanisms behind these cracks in different dimensions. "Thermal expansion and contraction is when the fruit swells with heat during the day and contracts as temperatures drop at night. This daily tug-of-war exerts a lot of pressure on the skin."
He elaborates that water balance occurs when high transpiration rates during hot days are followed by increased root pressure at night, pushing water into the fruit when it's least able to handle it. This spike in hydrostatic pressure can cause the skin to burst. "Temperature extremes directly affect the flexibility of the cuticle. When this protective layer loses its elasticity, it can't stretch with the expanding fruit, making it more vulnerable to cracking."
Factors that also influence cracking
Addressing tomato cracking, therefore, requires an integrated approach. "It's not just about managing temperature," he emphasizes. "You also need to consider water fluctuations, humidity levels, and root zone health. Each factor contributes to the fruit's ability to adapt to environmental changes."
He notes the influence of genetic and developmental factors. "Some tomato varieties are naturally more resistant to cracking. Selecting the right cultivars can be part of the solution," he advises. "But even the best variety can crack under stress if other variables aren't managed—like nutrient imbalances, overly rapid growth, and excessive light exposure."
Practical solutions for growers
To reduce the risk of cracking, he recommends a combination of strategies, starting with consistent irrigation. "Avoid wide fluctuations in watering. Drip systems can help maintain steady moisture levels." Humidity control is another important strategy. "High humidity at night can exacerbate water retention in fruit. Good ventilation is key." He adds that greenhouses should be equipped with shading, ventilation, and, if possible, active cooling systems to limit extreme swings.
When it comes to nutrition, he believes in balance. "Overfeeding, especially with nitrogen, can stimulate rapid growth that outpaces the skin's ability to stretch."
Ultimately, Umair highlights that awareness and proactive management are the best tools farmers have. "Tomato cracking isn't a random event—it's a reaction to specific environmental and physiological stresses. When you understand those triggers, you can take meaningful steps to minimize the damage and maintain fruit quality."
For more information:
Umair Anwar
+971 50 707 4215
+923 12 013 3636
umairanwarawan@gmail.com
www.linkedin.com/in/engr-umair-anwar
Global Farms
farms.global