Rape during the growth and development process, often due to poor management, or the lack of a certain kind of nutrients, resulting in growth and development are blocked, there are different degrees of yellow leaves, dark purple leaves, brown leaves, red leaves, purple blue leaves and gray leaves and other phenomena. According to the changes in leaf color, the cause of the unfavorable change in leaf color can be diagnosed, and appropriate countermeasures and remedies can be taken in time to facilitate the acquisition of high yield.
1, yellow leaf diagnosis. Yellow leaves appear in rape because of lack of nutrition or acid damage.
(1) Yellow nitrogen deficiency leaves. Rapeseed lacks nitrogen at seedling stage, the plants are short, the leaves are small, and the new leaves are born slowly. The leaf color is gradually light yellow, yellowish green or yellow, or the edge of the lower stem leaves yellow and gradually expands. At this time should be timely fertilizer, topdressing ammonium bicarbonate 15-20 kg per acre, or urea 5 to 8 kg, can also be used 1% -2% of high-quality urea spray foliar.
(2) Sulfur-deficient yellow leaves. Sulfur in rapeseed, short and thin root system at seedling stage, small and small leaves, the whole plant was pale green, but the color of young leaves was deeper than the old leaves. The yellow-deficient yellow leaves have different performances from the yellow-deficient yellow leaves. The sparse yellow leaves begin to yellow from the young leaves, and the nitrogen deficiency develops from the old leaves to the new leaves. The two are easy to distinguish. The sulfur-deficient rapeseed can be combined with cultivator, 10 kg of gypsum powder per acre, and topdressing nitrogen fertilizer to promote the yellow leaves to green.
(3) Sour yellow leaves. The acidity of the soil caused by the acidity of the yellow leaves often manifests as the yellowness of the new leaves, followed by shedding.
When rape has yellow leaves, 50 kg of lime per acre and 50 kg of grass ash are used to neutralize acidity of the soil to eliminate acid damage.
2, the diagnosis of dark purple leaves. The rape appeared dark purple due to lack of phosphorus. Phosphorus-deficient plants grew slowly and were dwarfed, the leaves became smaller, the leaves became thicker, the leaves were dark green or gray-green, lacking luster, purple petiole, purple-purple spots on the edge of the veins, dark purple in severity, and gradually withered.
Rapeseed lack of phosphorus treatment measures: 25 to 30 kilograms of superphosphate per acre topdressing, or with 12 superphosphate extract evenly sprayed, sprayed 2-3 times, each with a good fertilizer solution 60- 70 kg, or with 0.2% -0.3% potassium dihydrogen phosphate solution evenly sprayed, sprayed 2-3 times, each time interval 5-7 days.
3, the diagnosis of brown leaves. Rape leaves appear brown, which is a manifestation of potassium deficiency. Rapeseed lack of potassium, leaf chlorosis showed large spots of water-stained needles, veins significantly darker, shrinkage thickening, the leaves gradually coke, forming a "focal edge." When potassium is severely depleted, the heart of the plant atrophies and becomes brown, until the whole plant withers.
Treatment measures: Potassium deficiency at seedling stage, 7-10 kg of potassium chloride per mu, or 100 kg of plant ash; Potassium dihydrogen phosphate 0.1%-0.2% 60～ Spray evenly at 70 kg, spray 2-3 times, about 7 days apart.
4, red leaf diagnosis. Rapeseed leaves contain not only chlorophyll but also anthocyanins, which make the leaves red. Nitrogen is an important substance for the production of chlorophyll. If there is insufficient nitrogen, the chlorophyll in the leaves will be reduced, and the anthocyanin will show up, and the leaves will turn red from green. This shows that nitrogen deficiency is the main reason for the redness of rape leaves, and nitrogen deficiency is caused by many factors.
(1) Dry red leaves. The soil is prone to water shortage for a long time, and it is difficult for the plants with fertilizers to absorb water. Rape is affected by drought, its growth is slow, the plants are short, and the leaf color becomes light red. At this time, it should be watered and drought-resistant in a timely manner. In areas with conditions, it is possible to conduct furrow irrigation and avoid flooding and flooding, so as to avoid killing the roots.
(2) Waterlogged red leaves. In poorly-drained soils, plants are susceptible to knock-out, and rot and dead seedlings are aggravated. The higher the soil moisture content, the longer the duration, the higher the rate of rot and dead seedlings. Waterlogging in the field can cause roots and plants, poor root development, and reduced absorptive capacity, resulting in maladjusted nutrient supply and dark red leaves. In the management of the field, we must pay attention to open a good irrigation and drainage ditch, can irrigation and drainage, to ensure the normal growth of roots, eliminate redness and waterlogging.
(3) Infestation of red leaves. When the larvae of rape seedlings are seriously damaged, the leaves are atrophic, and the leaves are reddened. In this regard, it is possible to use 10% of the 50% anti-inflamy WP for 5 to 15 grams of water and evenly spray 50-60 kilograms of water. The control effect is good, or it can be homemade with tobacco lime mixture, ramie stem and leaf soaking solution, and tobacco garlic mixture. The prevention and control of soil pesticides is not only effective against flooding but also does not pollute the environment.
(4) Frost damage leaves. When the winter temperature drops below 0°C, the root absorption weakens, which results in physiological deficiency, chlorophyll production is blocked, and anthocyanins are presented in large amounts, rendering the leaves purple-red. Generally, nitrogen fertilizer is used excessively, and the fields that grow too prosperous before winter have the most severe frost damage.
After freezing injury of rapeseed, it can be combined with cultivator to make roots. Mushi ash 100 kg, thickening the rhizosphere, can prevent cold wind invasion, enhance heat insulation, reduce frost damage.
5, the diagnosis of purple blue leaves. Rapeseed has purple-blue leaf spots that are caused by boron deficiency. Boron is an indispensable trace element in rapeseed. The lack of boron in rape, often shows that the leaves are dark green at first, the leaves are small, the leaves are thick and brittle, the leaf ends are rewinded, and the leaves are not flat. The edge of the middle and lower leaves begins to turn purple and gradually develops inwards. The veins and nearby tissues turn yellow to form blue-purple spots.
The remedy of boron deficiency in rapeseed: 150-200 grams of borax per acre is applied to the water with nitrogen fertilizer, or 50-100 grams of borax per acre, 50 kg of water, and foliar spraying in sunny afternoon. Generally, it can increase production by 10%-20%, severely lacking boron land, and applying boron fertilizer can increase production by 30%-50%.
6, the diagnosis of gray leaves. The grayish white leaves of rape are caused by zinc deficiency. Symptoms start with the leaf margins, pale leaf color fades to gray, and then to the middle development, yellow and white irregular lesions on the leaves, tip overhangs, zinc deficiency symptoms when the fine root school, with zinc sulfate per acre 1 ~ 1.5 kg topdressing, or with 0.3% -0.4% zinc sulfate for foliar spray, even spray 2 to 3 times, each time about 5 days.
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