Symptom Identification and Prevention Methods for Potato Cold Injury

During plant growth or during tuber storage, if the air temperature or soil temperature is too low (above freezing), the plant will suffer cold injury. The degree of cold injury varies with the temperature. 1. Leaf symptoms At the seedling stage, after the plant suffers freezing injury, the leaves quickly wilt and collapse. When the temperature becomes warmer, the affected parts become water-soaked and turn brown after dying. However, if the plant suffers only cold injury, the above symptoms will not appear. Cold injury occurs at the seedling stage in early spring. The symptoms appear at the top of the seedlings, showing light yellow to light brown at the base of the young leaves. When the leaf primordia, stem primordia, and organelles suffer cold injury, the symptoms will appear after the young leaves grow out. Only one side of the leaf develops; the young leaves curl irregularly and develop chlorotic spots; the leaves are distorted. Sometimes mottling appears on the affected stems; necrotic spots may also appear on the young leaves. 2. Tuber symptoms Tubers suffer cold injury and freezing injury both in the field and during storage. After frozen tubers thaw, their tissues gradually change from white (or the basic background color) to pink or red, and then to gray, brown, or black. The frostbitten tissues quickly soften and rot. After the water evaporates, they become lime-like residue. Cold-injured tubers show netted necrosis on the cross section, which is a sign of phloem injury. Because the phloem is more sensitive to low temperature than the surrounding parenchyma cells. Netted necrosis may cover the entire tuber, or may be distributed only on the affected side. As cold injury worsens, dark brown spots appear around the vascular bundle ring, usually more severe near the umbilical end. The pink lesions inside the tuber may also be caused by cold injury. 3. Prevention of low-temperature cold injury For the damage caused by low temperature, only preventive measures can be taken. In early spring, attention should be paid to weather changes. If a cold wave occurs, smoke can be used in the field at night, or straw, green manure, and similar materials can be used to cover the plants. In addition, during storage, attention should be paid to temperature changes, and the tubers should be kept warm to prevent low-temperature cold injury. Xue Jian, Jiamusi Agricultural School, Heilongjiang Province