Evaluating water stress in irrigated durum wheat based on remote sensing technique

The Mediterranean water resources are almost fully exploited in many areas and the impacts on water scarcity are projected to multiply under climate change. The most effective mean to save water appear to be through the adoption of carefully managed irrigation strategies. Plant indicators enable the grower to use the plant directly for clues as to when irrigate. These indicators could be obtained through the use of remote sensing that is widely involved in numerous disciplines such as agriculture. Remote sensing is one of the solutions that can significantly contribute to providing a timely and accurate imagery of the agricultural sector. The main objective of this study is to compare satellite and ground-based sensing techniques as tools describing the variations of crop stress related indices under different water regimes (case of durum wheat). The experimental layout was established in Policoro (Matera) located in Southern Italy about 3 km far from the Ionian coast. The growing season was from February to June 2015 with three distinguished water management practices (rain-fed, 50% and 100% of irrigation requirements). The Landsat 8 images and ground-based sensing data were acquired regularly in April, May and June together with plant physiological parameters. The overall results indicated no significant differences of both biomass and yield among the irrigation regimes. This could be explained by the abundant precipitation (205 mm) which limited the needs for irrigation. Correlated to the leaf gas exchange parameters, Water Index (WI), CWSI_Jackson and CWSI_Alves and Pereira performed better than CWSI_Idso. Water Deficit Index (WDI) was found strongly related to plant water status, than Crop Water Stress Index (CWSI) with average R² of 0.96 in respect to 0.57 (CWSI_Idso). High correlation appear to be evident for satellite and ground-based derived WDI regressions (R²=0.81). Nevertheless, the satellite data could provide reasonable indications about the crop status when other means of measurement are missing.