Assessment of soybean injury from glyphosate using airborne multispectral remote sensing

Abstract

BACKGROUND

Glyphosate drift onto off‐target sensitive crops can reduce growth and yield and is of great concern to growers and pesticide applicators. Detection of herbicide injury using biological responses is tedious, so more convenient and rapid detection methods are needed. The objective of this research was to determine the effects of glyphosate on biological responses of non‐glyphosate‐resistant (non‐
GR
) soybean and to correlate vegetation indices (
VIs
) derived from aerial multispectral imagery.



RESULTS

Plant height, shoot dry weight and chlorophyll (
CHL
) content decreased gradually with increasing glyphosate rate, regardless of weeks after application (
WAA
). Accordingly, soybean yield decreased by 25% with increased rate from 0 to 0.866 kg
AI
ha
−1
. Similarly to biological responses, the
VIs
derived from aerial imagery – normalized difference vegetation index, soil adjusted vegetation index, ratio vegetation index and green
NDVI
 – also decreased gradually with increasing glyphosate rate, regardless of
WAA
.



CONCLUSION

The
VIs
were highly correlated with plant height and yield but poorly correlated with
CHL
, regardless of
WAA
. This indicated that indices could be used to determine soybean injury from glyphosate, as indicated by the difference in plant height, and to predict the yield reduction due to crop injury from glyphosate. Published2014.Thisarticle is a U.S.Government work and is in the public domainin the USA.