Wheat grain yield and nitrogen uptake prediction using atLeaf and GreenSeeker portable optical sensors at jointing growth stage

Abstract

Rapid acquisition of information about nitrogen (N) uptake and grain yield is an essential step in making site-specific in-season fertilizer N management decisions. The objective of this study was to quantify and validate the relationships between N uptake and grain yield of wheat using in-season measurements with atLeaf chlorophyll meter and GreenSeeker optical sensor at Feekes 6 growth stage (jointing stage) of wheat. The relationships were developed using data generated from experiments with multi-rate fertilizer N treatments and conducted in two consecutive wheat seasons (2017/2018 and 2018/2019) at two locations in the western Nile Delta of Egypt. A power function based on atLeaf measurement at Feekes 6 stage of wheat could explain 55.3% and 53.3% variations in the N uptake at this stage and grain yield at maturity, respectively. Measurements with GreenSeeker were related with N uptake and yield of wheat through exponential function and could explain 68.5% and 60.6% of the variation in N uptake and grain yield, respectively. The developed models were validated on an independent data set from another field experiment on wheat. The normalized root mean square error for the relation between atLeaf measurements and N uptake and grain yield were fair, whereas the fits were good for measurements with GreenSeeker. This study reveals that atLeaf chlorophyll meter and GreenSeeker optical sensor can be successfully used for establishing site-specific N management strategies in wheat.

Keywords

• N uptake
• Grain yield
• Wheat
• atLeaf sensor
• GreenSeeker sensor