What causes wheat not to head out

     Recently, the “Science and Technology 110” innovation studio of Agricultural Science and Technology News received a call from a wheat farmer surnamed Lou in Xilouzhuang Village, Yanjin County, Xinxiang City, Henan Province, saying that his family planted 15 mu of wheat this year, and it has not headed out yet, and he is very anxious. In their village alone, there are another two thousand mu of wheat that likewise has not headed out, and the villagers are at a loss. At the same time, a reader surnamed Zhang from Chenjiayuan Village, Liulin Town, Fengxiang County, Shaanxi Province, said that their family's wheat also has not headed out. On this issue, the reporter interviewed Wang Rui, a wheat expert at the College of Agronomy of Northwest A&F University, and Wang Mingqi, a wheat breeding expert at Northwest A&F University.

Freeze damage causes wheat not to head out

Wang Rui analyzed that the late spring cold spell some time ago caused temperatures to drop sharply, subjecting the wheat to freeze damage, which directly manifested as difficulty in heading out. At the same time, for wheat fields showing signs of total crop failure, farmers are advised to destroy them as soon as possible and replant other suitable crops; for wheat fields with less severe damage, timely control of other wheat pests and diseases should be carried out.

Wang Mingqi said that wheat freeze damage refers to the stagnation of wheat ear growth caused by a wheat field experiencing continuous low-temperature weather. In wheat fields with lighter freeze damage, after the young ears of the main stem and large tillers are frozen, they can still head out and set grain normally; but the number of grains per ear is noticeably reduced. When the freeze damage is relatively severe, the young ears of the main stem and large tillers and the heart leaves are frozen to death, while the remaining parts can still grow; in wheat fields with severe freeze damage, the wheat leaves and leaf tips become hard and brittle as if scalded by water, then turn to green wilt or green wilt into a blue-green color, and the stems and young ears shrink and die. The main types of wheat freeze damage are: early winter freeze damage, winter freeze damage, early spring freeze damage and late frost freeze damage.

Wang Mingqi said that the problem reported by the wheat farmers was mainly caused by early spring freeze damage and late frost freeze damage. Late frost freeze damage occurs during the period from jointing to heading of wheat (late March to mid-April). At this stage, wheat grows vigorously and has very weak cold resistance, and is extremely sensitive to low temperatures; if the temperature drops suddenly, frost damage is very likely to form. Late frost freeze damage occurring after jointing and before booting generally has no obvious external symptoms, and mainly involves the young ears of the main stem and large tillers being frozen. At the same time, depending on the period and severity of the wheat freeze damage, the extent of yield reduction varies greatly, and plots with severe freeze damage basically suffer total crop failure. Early spring freeze damage reduces wheat yield by 5%-30%, and late frost freeze damage reduces wheat yield by 15%-60%.

Remediation must be timely

Wang Rui said that when freeze damage occurs in wheat, remediation must be timely. 1. Main remediation measures for winter freeze damage: 1. Apply nitrogen fertilizer in a timely manner to promote the rapid growth of wheat tillers. 2. Strengthen fertilizer and water management in the middle and late stages to prevent premature senescence. 2. Main remediation measures for early spring freeze damage: 1. Moderately suppress growth in overly vigorous wheat fields, which can be done by compaction, and spray Zhuangfeng'an at the wheat standing stage. 2. Irrigate to prevent early spring freeze damage. 3. Fertilize and water after early spring freeze damage. 3. Main remediation measures for low-temperature cold damage: spraying Albit before low temperatures arrive, smoking and other methods can prevent and reduce the occurrence of low-temperature cold damage, and fertilizer and water should be applied in a timely manner to ensure normal grain filling of wheat and increase grain weight.