Diagnosis of soil moisture in greenhouse based on canopy leaf-air temperature difference
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DOI:10.7606/j.issn.1000-7601.2012.01.16
Key Words: tomato  canopy leaf-air temperature  soil volumetric moisture content  meteorological factor  evapotranspiration
Author NameAffiliation
LIU Chan Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling, Shaanxi 712100, China
Graduate School of Chinese Academy of Sciences, Beijing 100049, China 
FAN Xingke Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling, Shaanxi 712100, China
Northwest A&F University, Yangling, Shaanxi 712100, China 
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Abstract:
      According to measured result of canopy temperature, air temperature, soil moisture and some relevant meteorological factors during tomato’s whole growth in sunlight greenhouse conditions, analysis was made respectively of the relationship between canopy leaf-air temperature difference and soil water content and relative humidity. The result showed that: In the sunlight greenhouse condition, there were some peaks in the diurnal curve of canopy le af air temperature difference from tomato’s seedling stage to fruiting period, and the maxmum of canopy leaf-air temperature difference’s value appeared during 13∶00~15∶00 each day. Accoding to the data at 13∶00~15∶00 in tomato’s main growth period, we found that there was a significantly good correlation among canopy leaf air temperature difference (△T), water content (SW) and relative humidity (RH), combined with water content and relative humidity on the comprehensive influence of the △T. We can get a result which is the △T has a negative relationship with water content and has a positive with relative humidity, R2 is 0.778. By partial correlation analysis, we concluded that the SW was the most important factor which affected △T, which was a n egative linear correlation equation, and the R2 is 0.778. After validated with the measured data, it was found that the measured SW (Y) was well correlated with the simulated one (X), and R2 is 0.723. Therefore, we could get scientific basis for diagnosis of farmland soil moisture from the water status data which wa s monitored from canopy leaf air temperature difference at 13∶00~15∶00.