Relationship of Corn Yield, Biomass, and Leaf Nitrogen with Normalized Difference Vegetation Index and Plant Height

The strength of the relationships of corn (Zea mays L.) yield, plant biomass, and leaf N concentration with early- to mid-growing season combined normalized difference vegetation index (NDVI) and plant height measurements has not been adequately documented. The objective of this study was to compare the strength among the relationships of corn yield, plant biomass, and leaf N with combined and respective NDVI and plant height measurements taken during the early to mid-season under major cropping systems. Two field N rate response studies in non-irrigated corn after soybean [Glycine max (L.) Merr.] (CS), non-irrigated corn after cotton [Gossypium hirsutum (L.)] (CCT), non-irrigated corn after corn (CC), and irrigated corn after soybean (ICS) were conducted at Jackson and Milan, TN, from 2008 through 2010. Regressions of corn yield, plant biomass, and leaf N concentration with NDVI x plant height and NDVI + plant height were slightly to markedly stronger in terms of R-2 values than those of corn yield, plant biomass, and leaf N with NDVI alone during 6-leaf growth stage (V6) to 12-leaf growth stage (V12) regardless of cropping system. No strength difference was observed between the regressions of corn yield, plant biomass, and leaf N with NDVI x plant height or NDVI + plant height and with plant height alone. Our results suggest that the benefits are variable in using combined NDVI and plant height measurements to assess corn growth and N nutrition and/or predict corn yield relative to the utilization of NDVI measurements alone during the early- to mid-season.