What to Do When Wheat Seedlings Show Abnormal Leaf Color? A Full Analysis of Causes and Solutions

@#@245@#@After sowing and seedling emergence, various abnormal discolored seedlings often form due to the influence of natural conditions and cultivation practices. To make it easier to manage according to the specific seedling condition and the specific cause, they are introduced separately below:

Yellow-leaf seedlings - the causes of yellowing of wheat leaves.

First, soil drought. This situation mostly occurs in wheat fields with insufficient subsoil moisture or where moisture escapes through cracks. Its characteristics are: tillers emerge slowly, leaf color is grayish green, the central leaf is short and small, growth is slow or stagnant (people call this "shrunken-heart seedlings"), the middle and lower leaves gradually turn yellow and dry up, and roots are few and fine. Key management points: combine with watering and apply 15 kg of ammonium bicarbonate per mu as a topdressing.

Second, nitrogen deficiency. The seedlings are thin and weak, standing upright, with reduced tillering and narrow, short leaves. The lower leaves begin to turn yellow and dry from the leaf tip and gradually spread to the upper leaves. Key management points: use 7-8 kg of urea per mu, or 20-25 kg of ammonium bicarbonate, or 600-700 kg of human and animal manure and urine, applied in furrows between rows or watered on after dilution.

Third, hard and compacted soil. Because the soil lacks moisture and air, root extension is difficult, causing wheat leaves to be yellow and short and tillers to fail to appear on time. Key management points: first water in time, then carry out deep intertillage loosening of the soil to break up the hard layer.

Fourth, excessive seeding rate. It appears as crowded seedling growth, with competition for light, nutrients and water, and plants that are yellow, thin and weak. Key management points: first promptly thin the seedlings, especially the clustered seedlings at field corners, field edges and within the field, which should be thinned early and severely, then combine with watering and apply a small amount of quick-acting nitrogen and phosphorus fertilizer to make up for excessive consumption of soil nutrients and help the wheat seedlings turn from weak to strong.

Fifth, insect pests. Damage by wheat aphids or red spiders can also cause wheat leaves to turn yellow. Key management points: once damage is found, promptly spray with a 1500-2000 times dilution of 40% omethoate.

Red-leaf seedlings - the causes of red-leaf seedling formation.

First, waterlogging. Excessive rain during the autumn seedling stage or waterlogging damage in low-lying wheat fields can turn leaves dark red, and in severe cases cause root rot and seedling death. Key management points: promptly open deep ditches to drain and remove waterlogging, and apply a small amount of quick-acting fertilizer to promote early seedling growth.

Second, phosphorus deficiency. When wheat seedlings lack phosphorus, root development is poor, secondary roots are few and weak, leaf color is dark green and lusterless, leaf tips and leaf sheaths are purplish red, the plant is thin and small, tillering is delayed, the number of tillers decreases, and there may even be no tillering. Key management points: combine with hoeing and soil loosening, use 20-30 kg of superphosphate per mu, applied in furrows between rows or watered on after dilution; the earlier it is applied, the better the effect.

Third, salt-alkali damage. In plots with severe salt-alkali damage, patches of purplish-red "little old seedlings" often appear, and in severe cases seedlings die in spots and patches. Key management points: promptly hoe to increase temperature, break up crusting, inhibit salt return, and apply winter fertilizer at the right time to promote tillering and strong seedlings. In the following spring when wheat stands up, combine topdressing with irrigation to press down salts.

Fourth, freezing injury. In winter, when the temperature suddenly drops below 0°C, freezing injury to wheat seedlings can also cause leaves to turn red. Key management points: combine with hoeing and mounding soil around the roots, and broadcast 75-100 kg of plant ash per mu; if necessary, after wheat enters the overwintering stage, scatter a layer of "warm furrow manure" along the rows to protect the seedlings for safe overwintering.

Purple-leaf seedlings - when wheat seedlings lack boron, stems and leaves become thick and curved and leaves turn purple, forming "purple-leaf seedlings"; in severe cases, later there is "heading without grain set," which greatly affects yield. Key management points: use 150-200 g of borax per mu, together with an appropriate amount of nitrogen and phosphorus fertilizer, watered on after dilution, or use 50-100 g of borax per mu diluted in 50-60 kg of water for foliar spraying.

Brown-leaf seedlings - when wheat seedlings lack potassium, plant growth is slow, root development is poor and roots rot easily, leaves are dark green or blue-green and weak and drooping, leaf tips and margins turn scorched yellow and then brown, forming "brown-leaf seedlings." Key management points: use 15 kg of potassium sulfate per mu, or 100 kg of plant ash, applied in furrows opened between rows, or spray the foliage with a 0.2-0.3% potassium dihydrogen phosphate solution.