Due to the shallow roots of lettuce, the soil should be well-drained, fertile, water-retentive and fertile. Per acre Shi compost compost and human and animal manure 4000 ~ 5000 kg, 50 kg compound fertilizer. If the fertilizer is insufficient, the plants will not grow well, and it is easy to deflate beforehand. Summer and autumn lettuce growth temperature higher, more rain, it is appropriate to use deep trenches. After applying the base fertilizer, the depth of the ditch is about 15 centimeters, the width of the car is 1.2 to 1.6 meters, and 4 to 5 lines are planted in each compartment. When transplanting, select cloudy or late evening, transplant with soil, do not hurt the roots, and pour enough root water after transplanting in order to facilitate survival, such as sunny days after transplanting, shading nets can be used to shade, and survive in time. Removed.
1, spring lettuce, seedling age of 25 to 30 days, 5 to 6 leaf when the colonization, plant spacing 2027 cm. Depth is appropriate for burying in the base of the first petiole and pouring water after pouring. Listed on leaves, the spacing is 1520 cm. Covered with mulching film, the base fertilizer is applied once, and the mulch film is well covered. Greenhouses and open field cultivation, selected sunny and warm weather cultivating 1 or 2 times, timely watering topdressing, early feces and ground pouring, to keep the surface wet, when the plants are basically closed ridge, tender plants can be listed. With stems as the product, 15 kg of urea per acre is poured 1 or 2 times.
2, autumn lettuce, seedling age 25 days colonization, spacing 25 (30 ~ 35) centimeters, with tender strains listed, spacing 1520 cm. After selecting cloudy days or planting in the afternoon, the drowning water shall be poured in time, and the shade net shall be covered with a greenhouse, a small arch shed or a flat shed, and the seedlings shall be withdrawn after the seedlings are released. Less cultivator, shallow cultivator, dilute the ground and keep the soil moist. Before and after planting ridges, apply 3 to 4 per acre to compost 3000 to 4000 kg or 15 kg of urea 2 to 3 times.
3, winter lettuce, seedbed base fertilizer should not be excessive. About 40 days of seedling age is covered with mulching, with spacing (30~35) (30~40) centimeters. After the survival of topdressing 1 to 2 times of faecal water, such as the following year to adult plants listed, should pay attention to the hardening of the seedlings before the winter, should not be too fertilizer and water, to prevent overgrowth of the seedling stage, frozen before re-applying antifreeze fertilizer and water. The weeds were cleared in time in the spring and light cultivators were used once. The topdressing concentration was from small to large. After the stems began to expand, the frequency of topdressing decreased and the concentration decreased. In the case of mulching and greenhouse cultivation, sufficient base fertilizer should be applied and ventilation management should be observed.
4. The plant spacing at the time of planting differs depending on the variety and the season. The early maturing variety is about 20 cm 18 cm and the medium late maturing variety 30 cm 25 cm. In the season when the temperature is not high enough for the growth of lettuce, it can be planted densely; in the season when it is suitable for the growth of lettuce, it can be diluted.
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Roundness Measuring Instruments
Roundness meter is a length measuring tool for measuring roundness using the rotary axis method. The roundness meter is a measuring tool for measuring the roundness error of the workpiece using the rotary axis method. Roundness tester is divided into two types: sensor rotary type and workbench rotary type. During measurement, the measured part is installed concentrically with the precision shaft system, and the precision shaft is attached with an inductive length sensor or a workbench for precise circular motion. It is composed of sensor, amplifier, filter and output device of the instrument. If the instrument is equipped with a computer, the computer is also included in the system.Roundness Tester
The principle of the roundness meter is the same as that of the coordinate measuring machine. In fact, its working principle is very simple. The coordinate measuring machine is a point acquisition tool. Its principle is to collect points first, and then form a line from points, and then form a three-dimensional model from lines. CMM is a kind of measuring equipment that has a guiding mechanism, a length measuring element, a digital display device in three mutually perpendicular directions, and a worktable that can place the workpiece (not necessarily large or huge). The measuring head can be moved to the measured point easily by manual or motorized means, and the coordinate value of the measured point is displayed by the reading device and the digital display device. Obviously, this is the simplest and most primitive measuring machine. With this measuring machine, the coordinate value of any point in the measured volume can be displayed through the reading device and digital display device.
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