Estimation of the crop water stress index (CWSI) of sunflower (Helianthus annuus L.) using sensor-based irrigation scheduling for different irrigation levels.

The crop water stress index (CWSI) is an important technique for determining stress levels in the plant and directing irrigation management techniques. To determine the CWSI for sunflower, a pot-based research trial was carried out in the research field of the Department of Soil and Water Engineering, PAU, Ludhiana (India) during the summer of 2023. The sensor-based irrigation scheduling was carried out on the basis of the depletion of total available soil moisture (TASM). The drip irrigation treatments consist of I₁ (full irrigation), I₂ (20% depletion of TASM), and I₃ (40% depletion of TASM). The results revealed that the highest amount of water applied under I₁ was recorded at 484.4 mm, while I₂ (387.5 mm) and I₃ (290.7 mm) during the growing season of sunflower. The results revealed that for kernel diameter and seed weight, I₁ and I₂ were statistically non-significant to each other while I₁ and I₃ were statistically significant to each other. The highest water productivity recorded for I₂, followed by I₃. The overall findings revealed that an average CWSI value of 0.85 for the sunflower crop falls within the range of lower and upper baselines. The response of physico-chemical properties of sunflower seeds showed a high correlation with the draught condition. [ABSTRACT FROM AUTHOR]