Coefficient

Unit

Definition

P1

˚C day

Thermal time from seedling emergence to the end of the juvenile phase

P2

Days

Extent to which development is delayed for each hour increase in photoperiod above the longest photoperiod at which development proceeds at a maximum rate (which is considered to be 12.5 h).

P5

˚C day

Thermal time from silking to physiological maturity

G2

Number

Maximum possible number of kernels per plant.

G3

mg day−1

Kernel filling rate during the linear grain filling stage under optimum conditions

PHINT

˚C day

Phyllochron interval, the interval in thermal time between successive leaf tip appearances