Identification of Spectral Bands for Detecting Phosphorus and Nitrogen Deficiency in Winter Wheat.

Past research in winter wheat showed the potential of spectral indices to detect plant P (phosphorous) status although no specific indices were developed so far. An experiment was conducted at Perkins, OK in 2007/2008 to develop and evaluate spectral indices that can detect P and NP (nitrogen and phosphorus) deficiency in winter wheat. A randomized complete block design with three replications was employed. Treatments included factorial combinations of three rates of P (0, 34 and 67 kg P ha^-1) and four rate s of N (0, 56,112,168 kg P ha^-1). Four types of spectral measurements, namely, Spectrometer, green seeker sensor, four band sensor, and digital pictures were taken from each plot at Feekes 4, 5, 7 and 10. Additionally, wet and dry forage yield and forge P content were determined. Correlation analysis was used to test the relationship between the spectral readings and wet and dry forage yield, and forage P content of each treatment. This study will help to develop indices used to identify plant P deficiency independently and N and P in combination. The advantage of the index is to evaluate the mid season winter wheat P and NP status and to take an appropriate measure to maximize crop yield.