| Stage | Description |
| P1 (Juvenile Phase) | Time period or basic vegetative phase of the plant (expressed as growing degree days [GDD] in ˚C from seedling emergence during which the rice plant is not responsive to changes in photoperiod. |
| P2O (Critical Photoperiod) | Critical photoperiod or the longest day length (in hours) at which the development occurs at a maximum rate. |
| P2R (Photoperiodism Coefficients) | Extent to which phasic development leading to panicle initiation is delayed (expressed as GDD) for each hour increase in photoperiod above P2O. |
| P5 (Grain filling duration coefficient) | Time period in GDD) from beginning of grain filling (3 to 4 days after flowering) to physiological maturity with a base temperature of 9˚C. |
| G1 (Spikelet number coefficient) | Potential spikelet number coefficient as estimated from the number of spikelets per gm of main culm dry weight (less lead blades and sheaths plus spikes) at anthesis. |
| G2 (Single grain weight) | Under ideal growing conditions, i.e., non limiting light, water, nutrients, and absence of pests and diseases. |
| G3 (Tillering coefficient) | A higher tillering cultivar would have coefficient greater than 1.0 G4 (Temperature tolerance coefficient) = Usually 1.0 for genotypes grown in normal environments. |
| G4 (Temperature tolerance coefficient) | Usually, 1.0 for genotypes grown in normal environments. G4 for japonica type rice growing in a warmer environment would be 1.0 or greater. Likewise, the G4 value for Indica type rice in very cool environments or season would be less than 1.0. |