Measurements of Transpiration Rate of Sugarcane Plants and Estimations using Weather and Soil Moisture Data

• Published in: Research for Tropical Agriculture Vol. 13; no. 1; pp. 8 - 19
• Main Authors: KAWAMITSU, Yoshinobu, NAKABARU, Mai, TAKARAGAWA, Hiroo, DINH, Hoang T., WATANABE, Kenta, TAIRA, Eizo, IKEDA, Tsuyoshi, GOTO, Hideki, UENO, Masami
• Format: Journal Article
• Language: Japanese
• Published: Japanese Society for Tropical Agriculture 2020
• Subjects: pF; Smart agriculture; Sugarcane; Transpiration; Water saving irrigation; Water stress
• ISSN: 1882-8434; 2187-2414
• DOI: 10.11248/nettai.13.8

In order to stabilize sugarcane production by utilizing the limited water resources of the island area, it is necessary to determine the amount of irrigation while measuring soil moisture, evapotranspiration and plant conditions. In this report, we tried to estimate the rate of transpiration per plant, which is the basis of the water saving irrigation. Meteorological factors measured by the newly developed weather station (Halser View) and transpiration rate using an electronic balance were measured at 10-min intervals, and the relationship between those parameters were analyzed. The transpiration rate of sugarcane was measured under the following three conditions; 1) normal irrigation, 2) acute water stress, and 3) gentle water stress. As a result, under sufficient irrigation conditions, the transpiration rate of sugarcane plants could be regressed by solar radiation, vapor pressure deficit, temperature, and relative humidity. However, using the measured values for the first three days, we made a multiple regression model with these four factors as explanatory variables, and we could estimate the diurnal change of transpiration rate over the next 8 days with high accuracy. On the other hand, the irrigation was stopped and under the water stress of pF 2.5 and above the transpiration rate fell rapidly, almost to zero at pF 4. However, even under such water stress conditions, the diurnal changes in transpiration rate could be estimated by adding a correction term based on the soil pF value.Thus, the possibility of smart agriculture that can estimate the transpiration rate of sugarcane individuals using meteorological factors and soil moisture data and determine the timing of irrigation in real time has been shown.