| S.No | Short day Plants (SPD) | Long day plants (LDP) |
| (i) | Plants flower under photoperiods of less than critical day length. | Plants flower under photoperiods of more than critical day length. |
| (ii) | Interruption during light period does not inhibit flowering. | Interruption during light period inhibits Flowering |
| (iii) | Flowering is inhibited if long dark period is interrupted midway by a flash of light. | Flowering occurs if dark period is interrupted by light. |
| (iv) | Long continuous and uninterrupted dark period is critical for flowering. | Light period is critical for flowering. |
| (v) | Several plants flower under continuous dark if light is supplemented with sucrose. | Several plants flower under continuous light. The dark period is not at all required. |
