In recent years, the drought conditions due to changing climate patterns have adversely affected the U.S. agriculture. The 2012 drought that damaged major crops in Midwest was one of the most severe in last 25 years. It has resulted in losses of production, revenue, livestock and jobs, and has increased food prices. Under these circumstances, farmers are focused to use the water resources carefully. The researchers are working together to develop new crop varieties resistant to water stress and with improved yield. The crop improvement with new variety development is critical to maintain food security with changing environmental conditions and growing population. The genetic studies have improved significantly over the years with advancements in sequencing techniques that require less time and resources. An important aspect of crop improvement is evaluating crop traits or phenotypes. Currently, phenotype characterization or phenotyping is one of the major limitations to crop improvement studies in both controlled and field environmental conditions. Therefore, present work aims in developing non-invasive sensing tools as a means to evaluate water stress in crops.

 

This study was conducted using Foxtail Millet (Sertaria italica) as a model crop. Foxtail millet is widely grown in Northern China and India, and is known to grow in diverse ecological niches and is geographically distributed. In addition, it is closely related to maize and sorghum. As these grasses are used as model crops in studying C4 photosynthesis (photosynthetic mechanism occurring during elevated temperatures for improved energy efficiency in crops), they are widely used in abiotic stress studies. In this study, two levels of water stress were induced in foxtail millet crops by varying the watering frequency. The treatments were control (healthy), moderate- and extreme-stress conditions. Two non-invasive sensing techniques were used to evaluate the water stress in plant: the visible-near infrared spectroscopy and thermal imaging technique. The temperature profiles and the visible-near infrared spectral patterns between the stress treatments were evaluated using developed data processing and analysis procedures. The visible-near infrared technique is useful in assessing the physiological changes that occur in a crop as a result of stress. Thermal imaging results indicated the differences in temperature profiles between healthy and stressed crops. Overall, these two techniques can be applied in controlled environmental conditions for rapid sensing of crop water stress.