Response of Cotton Canopy Reflectance to Petiole Nutrients

In 2004, a study was conducted in the ‘Cutfield’ or Britain Farm at the Cotton Branch Experiment Station with five total N-fertilizer rates (0, 30, 60, 90 and 120 lb N/acre) on ‘FiberMax 960’ (FM 960) cotton (Mozaffari et al., 2005). The experimental design was a randomized complete block design with 5 treatments and 4 replications, resulting in 20 plots. Each plot was approximately 115 ft long and 25 ft wide allowing for eight rows of cotton with 38-inch wide rows. Cotton was planted on 22 May and managed following standard cultural practices for eastern Arkansas. Seedlings emerged on 29 May and first bloom occurred on 21 July. Cotton was harvested with a combine equipped with an AgLeader PF 3000 Yield Monitor on 12 November. Nitrogen fertilizer was applied in split applications with no pre-plant application. The first N application was made on 14 July, which included rates of 0, 30, and 60 lb N/acre. Total N rates of 90 and 120 lb N/ acre received only 60 lb N/acre nitrogen on 14 July. On 4 August, the 90 and 120 lb N/acre rates received a second application of 30 and 60 lb N/acre, respectively. Canopy reflectance of cotton was measured on 17 and 27 July. Since the data were collected before the second application of N, only 3 rates of N were used for data analysis. Canopy reflectance was measured with a hand-held StellarNet EPP2000-NIR-InGaAs-25 BACKGROUND INFORMATION AND RESEARCH PROBLEM