Cracking of storage roots

Cracking of storage roots is a physiological disorder rather than a pathogen-induced disease, characterized by the splitting of the epidermis and outer tissue layers of the root. It results from an imbalance in the growth rates of internal tissues compared to the outer skin, often triggered by environmental stress.

A wide range of root and tuber crops are susceptible to this condition, including carrots, beets, and radishes, with sweet potatoes (Ipomoea batatas) being particularly prone to severe cracking. In sweet potatoes, the rapid development of storage roots makes them highly reactive to moisture fluctuations during the growing season.

The primary cause of this phenomenon is an irregular water supply, specifically heavy irrigation or rainfall occurring after a prolonged drought. This surge in water uptake leads to rapid cell expansion in the core of the root, which exerts pressure that the relatively rigid outer skin cannot accommodate, causing it to rupture.

The negative impact on crop value is significant, as cracked roots lose their commercial appeal and marketability. Furthermore, these physical wounds serve as entry points for secondary soil-borne pathogens, leading to rotting and substantial losses during post-harvest storage.

Preventative strategies focus on maintaining environmental stability throughout the crop's development. Agronomic best practices include:

• Ensuring a consistent and uniform irrigation schedule to avoid stress cycles.
• Using organic mulches to conserve soil moisture and buffer temperature fluctuations.
• Improving soil structure to ensure better drainage and aeration for root development.
• Selecting varieties with known resistance or tolerance to cracking disorders.