Relationship of cotton nitrogen and yield with Normalized Difference Vegetation Index and plant height

The strength of the associations of cotton (Gossypium hirsutum L.) yield and N nutrition with integrated Normalized Difference Vegetation Index (NDVI) and plant height measurements has been scarcely documented. The objective of this investigation was to compare the strength in terms of determination coefficient (R-2) among the associations of cotton yield and leaf N concentration with integrated and respective NDVI and plant height measurements taken at key growth stages. A field experiment was carried out on no-till cotton at Jackson and Milan in Tennessee during 2008-2010. Six N treatments of 0, 45, 90, 135, 179, and 224 kg N ha(-1) were implemented in a randomized complete block design with four replicates for all site years. Regressions of lint yield with NDVI x plant height and NDVI + plant height were sometimes stronger than those of lint yield with NDVI alone. Associations of leaf N concentration with NDVI x plant height and NDVI + plant height were similar to or variably stronger than those of leaf N with NDVI alone. Regressions of lint yield and leaf N with NDVI x plant height or NDVI + plant height were generally similar to those of lint yield and leaf N with plant height alone. Utilization of integrated NDVI and plant height measurements to predict cotton yield and/or assess N nutrition has variable advantages over the use of NDVI alone. Both integrated and respective NDVI and plant height measurements are more appropriate to be used to predict cotton yield than to assess N nutrition.