The growth of wheat can be broadly divided into two phases: the vegetative phase and the reproductive phase. The distinction between the two phases depends on events in the bud tip, or stem apex (i.e. the apical meristem if referring to the main stem) of the plant. The vegetative phase encompasses germination, and then a period during which growth from the stem apex gives rise only to vegetative tissues: leaves, tillers (i.e. the branches or side stems of grass plants), and adventitious roots.
Table 1.4 Growth stage scores of wheat plants.
| Decimal growth stages (DGS) according to Zadoks et al. (1974) | The scale of Feekes (1941) | ||||
|---|---|---|---|---|---|
| Major growth phases | Major division | Minor divisions described by n | Score | Description | Equivalent DGS score |
| Germination | 0n | n indicates development before leaf emergence i.e. from dry seed (n = 0) to first leaf at coleoptile tip (n = 9) | |||
| Leaf production | 1n | n is the number of unfolded leaves on the main stem to a max. n = 9 | 1 | Seedling emergence to three leaf stage | 10–13 |
| Tiller production | 2n | n is the number of tillers with their own unfolded leaf to a max. n = 9 | 2 | Start of tillering | 21–25 |
| 3 | End of tillering | 26–29 | |||
| Stem extension | 3n | n is the number of nodes to a max. of 6, then n = 7 for flag leaf just visible, and n = 9 flag leaf unfolded | 4 | Leaf sheaths lengthen | 30 |
| 5 | Leaf sheaths strongly erect | 30 | |||
| 6 | One node detectable | 31 | |||
| 7 | Two nodes detectable | 32 | |||
| 8 | Flag leaf just visible | 37 | |||
| 9 | Flag leaf emerged | 39 | |||
| Booting | 4n | n indicates degree of swelling of the boot | 10 | Booting | 45 |
| Ear emergence | 5n | n indicates proportion of ear or ears emerged | 10.5 | Full ear emergence | 59 |
| Anthesis | 6n | n indicates degree of completion | 10.51 | Start of anthesis | 60 |
| Grain expansion | 7n | i.e. droplet exuded when caryopsis squeezed changes from watery (n = 1) to milky (n = 7) | 10.54 | Caryopsis water ripe | 71 |
| 11.1 | Caryopsis milky ripe | 75 | |||
| Dough development | 8n | i.e. no droplet exuded from squeezed caryopsis, thumbnail imprint not retained (n = 3) to thumbnail imprint retained (n = 5+) | 11.2 | Soft dough | 85 |
| Ripening | 9n | Grain dry enough to harvest (n = 2) to seed with no primary dormancy (n = 7) | 11.4 | Harvest ripe | 92 |