Sugar beet before sowing against blight
Blight is the general name of the major diseases of sugar beet seedlings, also known as black foot disease, damping-off disease, seedling rot. In our province sugar beet production areas have varying degrees of occurrence, the general incidence of 30% -40%, severe plots caused by lack of seedlings broken ridge, or even destroy the species. If there is no good defense before sowing, it will inevitably affect the yield and quality of sugar beets.
Symptoms: The disease from the seed is not unearthed to the seedlings 3 on the true leaf stage can be the disease, generally 1-2 pairs of true leaf disease is the most serious disease. It can be divided into four types: soil rot dead type, standing dry type, triploid type, and main root rot type. Symptoms are usually watery immersed lesions on the hypocotyls of the young roots and leaves, which gradually turn brown to black, and the affected parts become finely splayed. When the disease was light, the plants remained normal green. Due to lesions only reached the epidermis or primary cortex of the seedlings, the pith had not yet been reached, the radicles had been peeled off, and the seedlings could return to normal, but they were easy to form gourd-shaped roots. Rotten larvae of seedlings form fork roots or deformed roots.
Incidence conditions: They vary according to the type of pathogen. Aquatic fungal seedling rot pathogens have a very close relationship with soil moisture, and the higher the humidity, the heavier the disease. Low temperature, heavy onset, poorly drained low-lying land, poor soil quality or poor soil texture, sowing of soil in case of rain, extensive soil preparation prior to sowing, low seed quality, weak seed germination, excessively low or high soil pH, Will cause sugar beet blight worse. The incidence of heavy sugar beet planting is also heavy.
Control methods: (1) Agricultural control. Fine soil preparation requires soil loosening, virtual irrigation, removal of weed roots, no waste, combined with fertilization to achieve the standards of deep, loose, flat, net, and fertilizer. After the harvest of the former crops, the use of autumn deep 25-30 Centimeters, winter suppression, early spring, to prevent loss. Between the rain and the convulsions. (2) Seed treatment. The resistant polyploids such as 303, 304, and 305 polyploidy varieties were used as stress tolerance. (3) Chemical control. Spread the bulb after 2-3 days before sowing to increase the germination rate and save seeds. In order to prevent blight, we can use Fumei to mix 0.25 kg of water and 50 kg of seeds. We can also use Bao Miaoling to mix 1 sachet of Bao Miao Ling for every 50 kg of seeds. (4) Rational rotation. The implementation of the rotation for 5-8 years or more should not be repeated. (5) Increase phosphate fertilizer. Apply 50 kg of phosphate fertilizer per acre to promote seedling growth and increase disease resistance.
A Rhomboid prism is a type of reflective prism which is commonly used to displace a laser beam without changing it's direction. Effectively a Rhomboid prism acts as a pair of single mirrors and have a shape where it's lateral displacement is equal to the length of the prism. In imaging applications a Rhomboid prism will be used to displace the optical axis without inverting the image.
They maybe coated to transmit part of the beam and product two parallel and displaced emerging beams. Generally our Rhomboid prisms are uncoated and rely on total internal reflection.
A prism is a polyhedron made of transparent materials (such as glass, crystal, etc.). It is widely used in optical instruments. Prisms can be divided into several types according to their properties and uses. For example, the "dispersion prism" that decomposes the composite light into the spectrum in a spectrometer is more commonly used is an equilateral prism; in a periscope, binocular telescope and other instruments, the direction of light is changed to adjust its imaging position. "Reflecting prisms" generally use right-angle prisms.
According to the law of refraction, light passes through a prism and is deflected to the bottom twice. The angle q between the emitted light and the incident light is called the deflection angle. Its size is determined by the refractive index n of the prism medium and the incident angle i. When i is fixed, different wavelengths The light has different deflection angles. In the visible light, the largest deflection angle is purple light, and the smallest is red light.
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