Assessment of Crop Water Stress Index (CWSI) of Sorghum Irrigated by Surface and Subsurface Drip Irrigation Methods under Mediterranean Conditions

OpenAlex İngilizce

In recent years, subsurface drip irrigation has become increasingly important in view of the increasing drought. As it is a newly developed method, the effects of subsurface drip irrigation (SSDI) and surface drip irrigation (SDI) need to be compared in terms of plant growth and yield parameters as well as water savings. The CWSI is an important index that indicates the water status in the plant and is closely related to yield and plant development parameters. The aim of the study is to compare the CWSI calculated with the SDI and SSDI methods in sorghum. The relationship between CWSI and physiological parameters (leaf number (LN), leaf area index (LAI), chlorophyll content (CC)), as well as bioethanol and juice yield are also evaluated in the study. The study was designed in a randomized complete block design to include two drip irrigation methods (SDI and SSDI) and five different irrigation treatments (I0, I25, I50, I75, and I100) in three replications in Antalya in 2017. The full irrigation treatment was applied when 40% of the available soil water capacity in the soil profile of 0-90 cm was depleted, while the deficit irrigation treatments were applied at 75%, 50% and 25% of the full irrigation treatment. Consequently, the upper limit value was calculated as 5.5oC and the lower limit equation was determined as Tc-Ta = -1.96*VPD-0.08 under Mediterranean conditions for the sorghum plant. Compared to the SDI treatments, lower CWSI values were calculated for the SSDI treatments. Additionally, it was determined that as the CWSI increased in sorghum, leaf number, leaf area index, and chlorophyll content values decreased and as a result, juice and bioethanol yield decreased. It was determined that there was a high level of exponential relationship and a strong negative correlation between CWSI-irrigation, CWSI-ET, CWSI-leaf number, CWSI-LAI, CWSI-CC, CWSI-Juice yield, CWSI-bioethanol yield, and CWSI-IWP for both irrigation methods in sorghum. Considering the lower CWSI and higher bioethanol yield, it was concluded that the SSDI method is more suitable for sorghum.