عنوان مقاله [English]
Determination irrigation time for sugarcane fields using infrared thermometer and measurement of soil moisture in root zone
Shadman Veysi1, Abdali Naseri2 and Saeed hamzeh3
1PhD student of Irrigation and Drainage Engineering, Faculty of Water Sciences Engineering, Shahid Chamran University of Ahvaz, Khuzestan, Iran, 2Professor at Faculty of Water Sciences Engineering, Shahid Chamran University of Ahvaz, Khuzestan, Iran, 3Faculty of Geography, Department of Remote sensing, University of Tehran, Tehran, Iran
Background and objectives: One of the important factors that reduce of sugarcane yield is short-term water stress between irrigation rounds. So that, the goal of this research is monitoring effectiveness parameters that determine water status of plant for irrigation scheduling and detection irrigation time.
Materials and methods: This research monitored CWSI at sugarcane fields from May-September 2015 in Salman Farsi agro industry unit. Four different ages of sugarcane fields (plant, Ratoon1, Ratoon2, Ratoon3) at CP69-102 variety were investigated. For detection CWSI, sugarcane canopy temperature using infrared thermometer at three directions was measurement. Second step of this research in places that canopy temperature was measured, the percentage of soil moisture at two depths (0-30 cm & 30-60 cm) were measured and relationship of Soil moisture with CWSI was investigated. Each round, eight fields that have same age and various irrigation days for monitoring has been selected (totally 32 fields). With a round of measurement at different ages to calibration the relationship between soil moisture and CWSI was done. At the second round of measurement validation was conducted. Relationship between soil moisture and CWSI was assessment.
Results: Lower baseline equation for CP69-1062 in all of the growth period , with R2=87% was estimated. Also upper baseline equation is horizontal line that vicinity 4°c varied. Results shown with increase of sugarcane age correlation between CWSI and Soil moisture was decreased. In other words, age of sugarcane is effectiveness parameter on absorb water to sugarcane. The results shown that the optimal amount of water stress index in all of sugarcane ages to start of irrigation is 0.5. Calibration equation shown RMSE=0.15 between observation and calculated CWSI. As so correlation between CWSI & soil moisture was low, so that the affection of irrigation water salinity is significant and salinity stress is important.
Conclusion: Generally, the results have shown that CWSI that was calculated from canopy temperature is good index to varied of plant water, so that utilize it for determine irrigation time and soil moister because of irrigation water salinity is not reasonable.
Keywords: water stress, Salman Farsi agro industry, Infrared thermometer, soil moisture, sugarcane