The Use of Plant Indices for In-Season Prediction of Cotton Lint Yield Response to Nitrogen Fertilization.

Nitrogen (N) fertilization has attracted concerns in many production systems. With the high cost of N fertilizers and the threat of N loss to the environment, increasing N use efficiency has become an important goal to maintain a productive and sustainable cotton industry.�� The use of plant indices is an agricultural technique for refining N-fertilizer recommendations.� The study was initiated at three sites in northern Louisiana in 2008 to identify in-season plant indices that can be used to evaluate cotton lint yield response to N fertilizer.� These plant indices consisted of normalized difference vegetation index (NDVI), chlorophyll readings, plant height and leaf N which were taken at early square, early bloom, two weeks after early bloom, and four weeks after early bloom. The response of in-season plant indices has potential to relate to cotton lint yield response to N.� Two-weeks after early bloom showed the highest number of similar predictions, between lint yield and midseason plant indices, with 16 of 24 predictions.� However, earlier growth stages, such as early square and early bloom, show a similar number of predictions.� Plant height and NDVI were the plant indices that show the best accuracy at predicting cotton's lint yield response to N fertilization, with correlation coefficients values of 0.53 and 0.32, respectively.� The incorporation of two or more plant indices shows potential to increase the predictability of cotton's lint yield response to N-fertilization at the early growth stages.�