ABSTRACT
Optimizing water use in aerobic rice: Evaluating drip irrigation strategies and crop water stress index under Mediterranean conditions

Yesim Bozkurt Çolak1*
 
Increased limited water resources coupled with the increasing effect of climate change calls for more efficient use of water in plant production in the Mediterranean region. Therefore, assessment of threshold level of crop water stress index (CWSI) is of paramount importance for precision irrigation scheduling for rice in 2019 and 2020 under the Mediterranean environmental conditions. The experimental treatments consisted of two irrigation methods namely surface drip (DI) and subsurface drip systems (SDI), three irrigation levels designated as plant pan coefficients (I1.00: Class A-pan (Ep) × 1.00; I1.25: Class A-pan Ep × 1.25 and I1.50: Class A-pan Ep × 1.50) and conventional flooding (CF) method as control plot. Canopy temperatures were measured throughout the growing season with an infrared thermometer and depending on the plant canopy temperature (Tc) and air temperature (Ta) difference (Tc - Ta) and air vapor pressure deficit (VPD), the equation of the lower baseline without water stress was determined as Tc - Ta = -2.2069VPD + 0.8263, and the upper baseline calculated under water stress conditions using values obtained from plants cut on different days was determined as 5.08 °C. Two years seasonal average CWSI values ranged from 0.09 in CF to 0.34 in SDI-I1.00. According to the obtained results, it was determined that the infrared thermometer technique could be used in the irrigation programming of rice. It has been determined that if this technique is used in Mediterranean conditions, irrigation scheduling can be done in such a way that the average CWSI value is kept around 0.15 for drip irrigation, which provides water savings throughout the season.
Keywords: Aerobic rice cultivation, crop water stress index, irrigation scheduling, paddy.
1Malatya Turgut Ozal University, Faculty of Agriculture, Department of Biosystems Engineering, Malatya, Turkiye.*Corresponding author (yesim.colak@ozal.edu.tr).