Remedies for rapeseed deficiency
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For rapeseed deficiency disease, it is essential to prevent it. Once symptoms appear, immediate remedial measures must be taken. In the absence of nitrogen in nitrogen-deficient rapeseed, the leaves are yellowish, weak in growth, and the plants are short. In general, nitrogen deficiency and red leaves are prone to occur when drought and fertilizer are released. Remedial measures: Apply 7.5 kg urea or 15 to 20 kg of ammonium bicarbonate per 667 square meters (1 mu) to 500-750 kg of water. Phosphorus-deficient rape plant growth is slow and dwarf, the leaves become smaller, the leaves are thicker, and the leaves are dark green or gray-green, lacking luster. Petiole purple, purple veins spots or plaques. The number of leaves is 2 to 3 fewer than that of normal plants. Remedy: Apply 25 to 30 kg of superphosphate per 667 m2 or spray potassium dihydrogen phosphate 2 to 3 times continuously. The shortage of potassium in rapeseed begins with the old leaves and develops toward the heart. It initially appears as a yellow spot, and there are "focal edges" and pale brown spots gradually appearing at the leaf tip and leaf margin. The leaves became thicker, harder, and more brittle. The mesophyll tissues were obviously "burned" and wilted. Remedial measures: Apply 7.5 to 10 kg of potassium chloride per 667 square meters to 500 to 750 kg of water or 100 to 150 kg of ash. Boron-deficient rapeseeds have a large demand for boron fertilizer, but the amount of boron in the soil is less, so rape is most likely to lack boron. Boron-deficient plant roots stopped growing, no root hairs and lateral roots, some had small nodules, and the root bark turned brown. Purple or blue-purple patches appeared on the leaves, leaf margins were recurved, and rhizomes were enlarged. Boron deficiency during flowering can lead to "flowering but not realizing", that is, the phenomenon of scarring after flowering. Remedial measures: 150 to 200 grams of borax per 150 to 200 grams of water for every 667 square meters, or 50 to 100 grams of borax 50 kilograms of water selected sunny afternoon foliar spray.