Conductivity Meter by the Four Electrodes Method and Measurement of Growth of Root System

关于根的测量方法很少，根像茎和茎一样延伸到地下。因为要探测地下的根系是非常困难的。他们尝试着用玻璃面墙的方法来探测它的视线，然后在这里尝试用电法测量地下的根系。首先，采用四电极法研制了新型电导率仪。四个栅栏型电极是为测量根系而开发的，因为它不会影响土壤中的水的渗流。用这种栅栏式电极和研制的电路研制的电导率仪具有良好的特性：(1)电导率范围宽，(2)电导率与电导率成正比，(3)重现性、稳定性、老化、其他因素的影响和两个电极之间的相互干扰，准确度高。四个栅栏式电极埋在土壤和琼脂中，用于比较和目视观察。当根从土壤或琼脂中吸收水分时，根附近的水分含量会发生变化。当根部靠近电极时，电极附近的水分含量发生变化，电导率也会下降。当根部距离电极达到5 mm时，就会出现这种现象。使用该仪器可以通过检测电导率的变化来测量根的生长。

There are quite few measurements about root which spreads under the ground as same as a stem and leves. Because it is very difficult to detect the root system in the ground. They are trying to detect it in sight by the way of "Glass-faced Profile Wall Method".Then, it is tried to measure the root system in the ground by the electric method here. At first, the new electric conductivity meter is developed by using the four electrodes method. The four hurdle-type electrodes are developed for measurement of the root system as it does not exert influence on the seepage flow of water in the soil. The conductivity meter with this hurdle-type electrodes and the developed electric circuit has good characteristics; (1) the wide conductivity range,(2) the linear output in proportion to the conductivity,(3) high accuracy in reappearance, stability, ageing, influence of other tings andmutual interference between two electrodes.Using this conductivity meter, the growth of root is tried to measure. The four hurdle-type electrodes are buried in the soil and the agar for the comparison and the observation in sight. As the root absorbs water from the soil or agar, water content changes near the root. When the root comes near the electrodes, water content near the electrodes changes and conductivity also decreases. It appears when the root reaches 5mm apart from the electrodes. The growth of root can be measured by detecting the change of conductivity using this meter.