RMSE	root mean square error
RRMSE	relative RMSE
AND	accumulated nitrogen deficit
NBI	nitrogen balance index
Flav	flavonoid
Chl	chlorophyll
TI	tillering
SE	stem elongation
PI	panicle initiation
BT	booting
HD	heading
GF	grain filling
NNI	nitrogen nutrition index
NSI	nitrogen sufficiency index
RAGDD	calculation of Relative Accumulated Growing Degree Days