Data from: Use of normalized difference vegetation index to assess N status and predict grain yield in rice

Fine tuning N recommendations requires an understanding of crop N status
and yield potential early enough in the growing season when changes to N
management can influence yields. Recent studies have demonstrated the
ability of Normalized Difference Vegetation Index (NDVI) to assess crop N
status and predict yield in wheat (Tricticum aestivum L.) and maize (Zea
mays L.); however, there has been relatively little such research on rice
(Oryza sativa L.). The objectives of this study were to determine how well
NDVI measured at the panicle initiation (PI) rice growth stage assesses
crop N status and predicts final grain yield. Nitrogen response trials
were established over a 4-yr period (10 site-years) at various locations
throughout the Sacramento Valley rice growing region of California.
Additionally, the relationship between NDVI and crop N status was
characterized across 28 on-farm plots representing a range of
environmental conditions and management practices. The NDVI at PI was best
correlated with total N uptake (NUP, r2 = 0.66), followed by N
concentration (NCONC, r2 = 0.54), and aboveground biomass (AGB, r2 =
0.51). The utility of NDVI was greatest at lower values of crop N status,
whereas at higher values, NDVI saturated. The NDVI at PI was positively
correlated with final grain yield (r2 = 0.58) indicating utility for
developing in-season yield predictions. While NDVI is a potentially useful
tool to improve N fertilizer management and develop in-season yield
predictions in rice, alternative indices that do not saturate would likely
provide a basis for a better tool.