ISWC OpenIR  > 水保所知识产出(1956---)
张正1; 刘国彬1,2; 李强3
Source Publication农业工程学报

二端子结构在测定根系电容时伴生的电极接触效应会影响根系电容的有效测量。分别采用二端子和四端子2 种
对含水率为25%~30%下最为明显。在土壤相对含水率为85%~90%时,2 种结构下玉米根系电容表征根系生物量的有效

Other Abstract

Validity measurement of electrical capacitance across a root system is the precondition for using electrical
capacitance method to estimate root biomass. When using two-terminal configuration to measure root electrical capacitance,
the parasitic electrode contact effect would affect validity measurement of electrical capacitance. The primary goal of this
study was to evaluate the validity of root electrical capacitance by four-terminal configuration compared with two-terminal
configuration to measure root biomass. Maize (Zea mays) were grown in pots containing a loessial soil. Each pot contained
one individual and its root system was measured under electrode configuration of two-terminal and four-terminal. The
measurements were conducted at stage of jointing, tasseling and maturity of maize, respectively. A total of 5 plants were
measured for each stage. Electrical capacitance of the root system was determined using a portable alternating current (AC)
digital capacitance bridge (MT-4080A) with a pure sine wave excitation at a frequency of 1 kHz. Home-made stainless, low
resistance electrode (5 cm in length and 2 cm in diameter), which was sharpened at one end and pushed into the soil vertically,
was used to connect root system and capacitance bridge. Before each measurement, the relative soil moisture of pots was
controlled to 25%-30%, 55%-60% and 85%-90%, respectively. Soil water content of pots was measured and controlled by
TDR-300 combined with the weighing method. In measurements under two-terminal configuration, one electrode was inserted
through the center of the stem about 1 cm from crown, and the other one was inserted into the soil about 5 cm from the base.
Compared with the two-terminal configuration, the four-terminal configuration used a further 2 electrodes which were placed
above the stem electrode and further from the base. After measurement of each pot, the roots were harvested and the biomas
was determined. The results showed that soil water content had an evident effect on electrode contact effect. The electrode
contact effect was presented and root electrical capacitance of maize measured by the two-terminal configuration was smaller
than the four-terminal configuration. The electrode contact effect increased with the decrease in soil water content and it was
the most obvious at the relative soil moisture of 25%-30%. In detail, compared with the two-terminal configuration, the root
electrical capacitance determined by the four-terminal configuration increased by 1.04, 0.21 and 0.04 times at relative soil
moisture of 25%-30%, 55%-60% and 85%-90%, respectively. Additionally, the validity of root electrical capacitance
characterizing root biomass was similar under two configurations at the relative soil moisture of 85%-90% (two-terminal
configuration: R2=0.63, P<0.05; four-terminal configuration: R2=0.66, P< 0.05). However, compared with the four-terminal
configuration, the validity of root electrical capacitance characterizing root biomass under the two-terminal configuration declined
sharply when soil water decreased, and it was most pronounced at the relative soil moisture of 25%-30% (R2 decreased from
0.59 to 0.37, P<0.05). In conclusion, compared with the two-terminal configuration, the validity of root electrical capacitance
characterizing root biomass under the four-terminal configuration was better when soil water content was lower.

Keyword土壤含水率 生物量 根系 电容 二端子结构 四端子结构 电极接触效应
Indexed By中文核心期刊要目总览
Document Type期刊论文
Recommended Citation
GB/T 7714
张正,刘国彬,李强. 四端子电极提高根系生物量电容法估测的有效性[J]. 农业工程学报,2017,33(5):185-189.
APA 张正,刘国彬,&李强.(2017).四端子电极提高根系生物量电容法估测的有效性.农业工程学报,33(5),185-189.
MLA 张正,et al."四端子电极提高根系生物量电容法估测的有效性".农业工程学报 33.5(2017):185-189.
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