Developing a Model for Estimating Leaf Temperature of Cnidium officinale Makino Based on Black Globe Temperature

흑구온도를 이용한 천궁 엽온 예측 모델 개발

Abstract

Background: The leaf temperature ($T_{LEAF}$) is one of the most important physical parameters governing water and carbon flux, including evapotranspiration, photosynthesis and respiration. Cnidium officinale is one of the important folk medicines for counteracting a variety of diseases, and is particularly used as a traditional medicinal crop in the treatment of female genital inflammatory diseases. In this study, we developed a model to estimate $T_{Leaf}$ of Cnidium officinale Makino based on black globe temperature ($T_{BGT}$). Methods and Results: This study was performed from April to July 2018 in field characterized by a valley and alluvial fan topography. Databases of $T_{LEAF}$ were curated by infrared thermometry, along with meteorological instruments, including a thermometer, a pyranometer, and an anemometer. Linear regression analysis and Student's t-test were performed to evaluate the performance of the model and significance of the parameters. The correlation coefficient between observed $T_{LEAF}$ and calculated $T_{BGT}$ obtained using an equation, developed to predict $T_{LEAF}$ based on $T_{BGT}$ was very high ($r^2=0.9500$, p < 0.0001). There was a positive relationship between $T_{BGT}$ and solar radiation ($r^2=0.8556$, p < 0.0001), but a negative relationship between $T_{BGT}$ and wind speed ($r^2=0.9707$, p < 0.0001). These results imply that heat exchange in leaves seems to be mainly controlled by solar radiation and wind speed. The correlation coefficient between actual and estimated $T_{BGT}$ was 0.9710 (p < 0.0001). Conclusions: The developed model can be used to accurately estimate the $T_{Leaf}$ of Cnidium officinale Makino and has the potential to become a practical alternative to assessing cold and heat stress.

Fig. 1. Relationship between black globe temperature and leaf temperature of C. officinale Makino.

Fig. 2. Relationship between observed leaf temperature and calculated leaf temperature of C. officinale Makino by linear regression equations of Fig. 1.

Fig. 3. Influence of solar radiation on temperature rise in the black globe.

Fig. 4. Influence of wind speed on coefficients of regression equations between wind speed and temperature change in black globe.

Fig. 5. Relationship between observed black globe temperature and calculated black globe temperature.

Fig. 6. Comparing air temperature, leaf temperature and black globe temperature during frost occurrence.

Fig. 7. Comparing air temperature, leaf temperature and black globe temperature during hot weather conditions.

Fig. 8. Changes in maximum black globe temperature and green area of C. officinale Makino during hot weather period.

Fig. 9. Change of canopy green area of C. officinale Makino during hot weather period.

Table 1. Influence of wind speed on temperature change in black globe under different wind conditions.