(1) Characteristics and requirements for environmental conditions: Cabbage cabbage is a cold vegetable for two years. Seeds can germinate in the range of 4 - 35 ° C, and the optimum temperature for germination is 18-22 ° C. From seeding to emergence for 2-3 days, seed germination requires light, so sowing should not be too deep. The seeds of Chinese cabbage have a short-term dormancy after seed collection, and generally disappear within 2 to 3 months. It is effective for promoting seed germination by low temperature treatment and gibberellin. The suitable temperature for growth at the seedling stage is 22 °C, and the growth temperature is below 5 °C. It can promote the flower bud differentiation of Chinese cabbage when the temperature is 3-13 °C. And the lower the temperature, the earlier the differentiation. Cabbage is beneficial when the soil moisture is 80% to 90% and the relative humidity of the air is 65% to 80%. A suitable soil pH is 5.5-7.0.
(2) Technical points of seedling cultivation: Cabbage cabbage is mainly cultivated in autumn. According to different maturity, the sowing time is in summer or early autumn. The main cultivation seasons and sowing dates in each place are shown in Table 34. The seedlings of Chinese cabbage are shaded and cooled. At the same time, we must strengthen the root protection measures. The seeding rate is 50-100 grams per mu, the seedling period is 15-25 days, and the seedlings can be planted when there are 3-8 true leaves. In the Yangtze River Basin and South China, spring cultivation can also be carried out. The sowing time is about from February to early March. The spring seedlings should be strictly controlled to prevent the seedlings from twitching by vernalization, generally not lower than 10 °C. To prevent the occurrence of diseases, we must pay attention to: 1 timely control of aphids, conditional should be used to isolate seedlings with mesh, to avoid the spread of viral diseases by aphids. 8 The roots of Chinese cabbage are weak, which is not conducive to future growth after injury. It is also easy to infect soft rot, so the root system should be protected from damage. 2 To control pests, the main pests include rapeseed larvae, small tigers, crickets, and aphids, as well as rapeseed and diamondback moths.
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When installing security Outdoor Camera, you should first choose the monitoring host. Do you want to add a monitoring card to your computer, or do you want to use an embedded hard disk recorder as your monitoring host. The computer monitoring card is more suitable for places that are familiar with computer installation, have professional personnel on duty, and have more functional requirements. Its overall investment is relatively low. Since the monitoring card is installed in the computer, the computer needs to be started 24 hours a day; As for the latter, it does not require professional knowledge, nor does it need to be on duty, and it is relatively simple to operate.
To install security monitoring equipment, it is necessary to determine how many cameras are installed, and the quality and monitoring range of the cameras are affected. It is preferred to determine how many cameras are used for monitoring, and then determine the camera lens monitoring range according to how many cameras are available. Therefore, the distance from the camera to the monitoring point and the monitoring area must be clear. The infrared supply network recommends using the camera of 480 TV line, because it is more in line with that definition.
When installing security monitoring equipment, the third consideration is whether the camera has night vision function. If the monitoring is installed in a dark place, it is necessary to consider using a camera with infrared night vision function.
The security monitoring equipment can be installed via wired or wireless transmission. Although the cost of wireless network is relatively high, it can save a lot of installation trouble and make the monitoring site more beautiful. However, the installation of wireless network monitoring equipment should take into account the environmental problems of security sites. Cement building materials will shorten the wireless transmission distance, and metal building materials may complete the shielding of wireless signals. The infrared transmitter and infrared receiver should be far away from other appliances to avoid interference. Because the price of wireless network is almost twice that of wired transmission monitoring equipment, I suggest using wired transmission installation.
On site monitoring and network monitoring When determining the installation of the monitoring system, you should consider whether you need network functions. That is, if you need to monitor and control the monitoring site on the Internet at any time, you need to select a monitoring host with network functions. Avoid no network transmission function after installation.
A complete security monitoring equipment should at least have three parts: surveillance camera, PTZ and decoder. The following are their installation methods:
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