Investigating the relationship between CWSI of sugarcane and soil moisture in two surface (closed end furrow) and subsurface drip irrigation systems

One of the important factors that reduce plant growth is the short-term water stress applied to the plant in the period of two irrigations. This research aims to investigate the relationship between crop water stress index (CWSI) of sugarcane and soil moisture under two systems of closed-end furrow irrigation (CI) and subsurface drip irrigation (SDI) at research station number one of sugarcane development research and training institute was done from July to September 2022. For this purpose, a field including ratoon 3, of the variety CP69-1062, with four replications for both irrigation systems was selected. First, the upper and lower baselines were determined for CI. Then, using these baselines, the average CWSI for SDI and CI systems was estimated for each month, separately. The highest value of CWSI for CI in September was 0.54 and for SDI in August was 0.49. Results showed that there is a high correlation between CSWI and soil moisture only in CI method for the depths of 0-30, 30-60 and 60-90 cm. The correlation between CWSI and soil moisture for CI was determined in the range of 0.60-0.70, and for SDI, in the range of 0.46-0.12. It seems that in addition to water stress, other stresses such as salinity stress caused by irrigation water and farm soil are also applied to the plant.