1. Phosphorus deficiency causes the whole plant of maize seedlings to turn red. When soil phosphorus deficiency can not meet the growth needs of maize seedlings, the growth and development of roots are hindered and the growth of seedlings is slow. Because the content of phosphorus in seedlings gradually decreases and chlorophyll synthesis is blocked, the leaves change from dark green to red or purple.
Control methods: Applying farmyard manure or phosphate fertilizer and spraying potassium dihydrogen phosphate foliar fertilizer on the leaves can effectively alleviate the occurrence of red leaves.
2. Low temperature causes the whole plant of corn seedlings to turn red. Low temperature can also cause corn seedlings to turn red. In Northeast China, corn is planted earlier, and in early spring, it will cause chilling injury due to "late spring cold", which will lead to the redness of the whole plant of corn seedlings. In this case, with the increase of temperature, the late red seedling phenomenon will gradually ease and disappear.
Control method: Plastic film mulching can effectively prevent the occurrence of red leaves in low-lying and cold corn fields.
3. The phytotoxicity and insect pests caused the maize seedlings to turn red. The sugar metabolism in maize seedlings was blocked by phytotoxicity and insect pests, and a large number of anthocyanins were produced, forming purple seedlings.
Control methods: clear weeds in the field, dig deep and level, eliminate the source of overwintering insects, and strictly control the occurrence of corn borer harm.
The accumulated water in the field caused the corn seedlings to turn red. Poor drainage in the field, high soil moisture, affecting root respiration and metabolism, hindered root growth, malnutrition, redness and purple.
Prevention and control methods: level the land, dig a drainage ditch, let the rain stop, and there is no water in the field.
In addition, the soil is too sticky, the sowing is too deep or too shallow, and improper fertilization causes "burning seedlings", which will lead to "red seedlings".
The low temperature in early spring is the most common cause of red corn seedlings, especially in low-lying areas, which is caused by weak root system and slow metabolism of seedlings. Of course, there is also a situation where red seedlings are easy to appear in phosphorus-deficient plots, and then genetic variation of seeds occurs, leading to bud mutation.
To prevent the occurrence of red seedlings, the first thing is: first, sow in time, and sow when the ground temperature reaches the level suitable for seedling growth. Secondly, sufficient phosphate fertilizer should be reasonably applied to the phosphorus-deficient plots according to the soil nutrient structure. Third, select seeds before sowing and pick out those seeds that are underdeveloped.