What should be done about stunted seedlings during rapeseed cultivation?
What should be done about stunted rapeseed seedlings? What methods can be used to prevent and control them? Please explain the symptoms of stunted rapeseed seedlings: after transplanting and recovering from transplant shock, during the early stage of field growth, stunted seedling symptoms sometimes appear, such as reddening and yellowing leaves, curled leaf centers, slow or halted growth, and poor growth and development. To prevent and control stunted rapeseed seedlings, targeted measures should be taken based on investigating the causes of the stunting...
What should be done about stunted rapeseed seedlings? What methods can be used to prevent and control them? Please explainSymptoms of stunted rapeseed seedlings:After transplanting and recovering from transplant shock, during the early stage of field growth, stunted seedling symptoms sometimes appear, such as reddening and yellowing leaves, curled leaf centers, slow or halted growth, and poor growth and development. To prevent and control stunted rapeseed seedlings, targeted measures should be taken based on investigating the causes of the stunting.
Causes of stunted rapeseed seedlings and solutions
I. Stunted seedlings caused by drought or waterlogging:Drought not only causes a lack of water in the plants, but is also accompanied by nutrient deficiency symptoms, such as reddening and purpling of leaves. Field investigation shows that the soil surface turns white and hardens, and may even crack; at noon on sunny days the plants may wilt. Stunted seedlings can also be caused by poor drainage in the transplanting field, or by continuous rainy weather after rapeseed transplanting, which causes oxygen deficiency.
For drought-induced stunted seedlings in no-till transplanting, furrow irrigation can be used, irrigating to 2/3 of the furrow depth and allowing the water to seep in and moisten the soil; for plowed transplanting fields, watering (sprinkling) to combat drought can be used, combined with topdressing, that is, applying a dilute fertilizer solution; for stunted seedlings caused by waterlogging, drainage ditches should be cleared or deepened to lower the groundwater level. Combined with intertillage, apply plant ash or rotted barnyard (compost) manure to raise soil temperature.
II. Stunted seedlings caused by fertilizer deficiency:Plants are short and small, with narrow leaves and yellow-green leaf color; in severe cases, the leaves at the stem base turn red, indicating nitrogen deficiency in the plants. Quick-acting nitrogen fertilizer should be applied in time, using 15 kg of ammonium bicarbonate per mu, applied as a drench with dilute manure water; if the upper leaves are dark green and lusterless, the lower leaves are purplish red, leaf emergence is slow, and root development is poor, these are symptoms of phosphorus deficiency.
For this, 0.3% potassium dihydrogen phosphate solution can be sprayed on the leaves 2 to 3 times, once every 3 to 5 days. At the same time, apply 25 kg of superphosphate per mu or 30 to 40 kg of calcium magnesium phosphate fertilizer. Before application, the phosphate fertilizer can be mixed with organic fertilizer, piled and fermented, and applied after decomposition; stunted seedlings may also be caused by boron deficiency, manifested as slow plant growth, and in severe cases root rot, dead heart, and purplish leaves. For this, 30 to 40 kg of 0.1% borax solution per mu can be sprayed on the leaves, or 0.5 to 1.0 kg of borax per mu can be mixed with 100 to 150 kg of water and drenched at the root.
III. Stunted seedlings caused by pests and diseases:The common one is severe damage by aphids, which causes plant stunting and thereby induces viral disease damage. For this, aphid damage must be strictly prevented; when localized aphid damage is found, 100% imidacloprid (imidacloprid, Yibianjing, Kangfuduo, Dagongchen) 2500 to 3000 times solution can be sprayed; when viral disease symptoms are found, promptly spray 5% Junduqing 300 to 400 times solution 2 to 3 times, once every 7 to 10 days. At the same time, pay attention to using 2.5% deltamethrin to control cabbage caterpillars, etc.
IV. Stunted seedlings caused by soil compaction:Due to compaction, plant root development is poor. Intertillage should be done well: the first time, hoe shallowly and finely, loosening the surface soil; the second time, hoe shallowly near the plants to scrape weeds, and hoe deeply between rows to loosen the soil and remove weeds.
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