Nitrogen is the most obvious nutrient element that affects plant growth, quality and yield. Applying nitrogen fertilizer can effectively increase the nitrogen content of the plant, but over-application of nitrogen will also reduce the plant quality and cause environmental pollution. The nutritional diagnosis of plants, understanding of the key period of their needs for fertilizer, realizing timely and quantitative supply of nutrients, can effectively improve the economic benefits of fertilization. The determination of nitrogen content in leaves is an important method for the nitrogen status of plants, but the analysis of total nitrogen is tedious, time-consuming, and time-consuming. It is very important to have an instrument for rapid measurement of nitrogen. The chlorophyll meter TYS-A and SPAD-502 are hand-held spectrometers that can quickly detect the chlorophyll content of plant leaves in the field without damage. Applied research on various crops shows that it can understand the status of plant nitrogen in situ, determine the timing of application of nitrogen fertilizer, the correspondence between the chlorophyll meter readings of plant leaves and the level of nitrogen application, the level of nitrogen nutrition of plants and the yield The interrelationships are intended to provide a basis for the use of chlorophyll meters to monitor the status of plant nitrogen nutrition and provide guidance for rational fertilization. The relationship between SPAD values ​​and nitrogen application levels and chlorophyll content was significantly correlated with the correlations between chlorophyll a, chlorophyll b, and total chlorophyll content (Figure 1). As shown in the figure, the increase in the reading of the chlorophyll meter with the increase in the amount of nitrogen significantly slows down and tends to reach an equilibrium level. The relationship between SPAD and total nitrogen content The total nitrogen content of mature leaves increased with the increase of nitrogen application rate. When the nitrogen application level was below N3, the total nitrogen content increased More. When the nitrogen application level exceeded N3, the increase decreased. The SPAD value of the mature leaves of plants was significantly positively correlated with the total nitrogen content. The total nitrogen content was high and the SPAD value was large. The SPAD readings of mature leaves vary with the growing season and are measured differently during different sampling periods. Generally, the seasonal change of plants takes place in the middle or late May, when the new leaf is still in a stage of rapid growth and maturation, and the chlorophyll content is low, and the SPAD value is also at a relatively low level. In spite of this, there is still a very significant positive correlation between leaf nitrogen content and SPAD readings, but the mathematical relationship between the two is different due to different sampling times. Although the national standard method can accurately measure the content of nitrogen, it takes a long time to test, has a large complexity, and has a bad influence on people's health. In contrast, the chlorophyll meter can quickly measure the SPAD value, and SPAD can quickly and effectively reflect the nitrogen content of the plant. Hand-held fast chlorophyll meter has become an indispensable product in the current research field. Panel Bender<batch artifact>.The AG series is a flexible and intelligent bending machine. Panel Bender,CNC panel bending machine,panel bender,panel bender vs press brake,panelbender,pressbrake,press brake machines FOSHAN RAGOS NC EQUIPMENT CO.,LTD. , https://www.ragosnc.com