The Zadoks scale is a cereal development scale proposed by the Dutch phytopathologist Jan C. Zadoks that is widely used in cereal research and agriculture.
Knowing the stages of development of a crop is critical in many management decisions that growers make. They are represented on a scale from 10 to 92. For example, in some countries, nitrogen and herbicide applications must be completed during the tillering stage. In France, the recommendation for the first nitrogen application on wheat is 6 weeks before Z30, with the second application on Z30. Wheat growth regulators are typically applied at Z30. Disease control is most critical in the stem extension and heading stage (Z31, Z32, Z35), in particular as soon as the flag leaf is out (Z37). The crop is also more sensitive to heat or frost at some stages than others (for example, during the meiosis stage the crop is very sensitive to low temperature). Knowing the growth stage of the crop when checking for problems is essential for deciding which control measures should be followed.
Examples of typical stages
- during tillering
- Z10: one leaf
- Z21: tillering begins
- during stem extension
- Z30: ear is one centimeter long in wheat
- Z31: first node visible
- Z32: second node visible
- Z37: flag leaf
- during heading
- Z55: the head is 1/2 emerged.
- during ripening
- Z92: grains are ripe
| Comparison of growth stage scales |
|||
|---|---|---|---|
| Zadok
Scale |
Feekes
Scale |
Haun
Scale |
Description |
| Germination | |||
| 00 | Dry seed | ||
| 01 | Start of imbibition | ||
| 03 | Imbibition complete | ||
| 05 | Radicle emerged from seed | ||
| 07 | Coleoptile emerged from seed | ||
| 09 | 0.0 | Leaf just at coleoptile tip | |
| Seedling growth | |||
| 10 | 1 | First leaf through coleoptile | |
| 11 | 1.+ | First leaf unfolded | |
| 12 | 1.+ | 2 leaves unfolded | |
| 13 | 2.+ | 3 leaves unfolded | |
| 14 | 3.+ | 4 leaves unfolded | |
| 15 | 4.+ | 5 leaves unfolded | |
| 16 | 5.+ | 6 leaves unfolded | |
| 17 | 6.+ | 7 leaves unfolded | |
| 18 | 7.+ | 8 leaves unfolded | |
| 19 | 9 or more leaves unfolded | ||
| Tillering | |||
| 20 | Main shoot only | ||
| 21 | 2 | Main shoot and 1 tiller | |
| 22 | Main shoot and 2 tillers | ||
| 23 | Main shoot and 3 tillers | ||
| 24 | Main shoot and 4 tillers | ||
| 25 | Main shoot and 5 tillers | ||
| 26 | 3 | Main shoot and 6 tillers | |
| 27 | Main shoot and 7 tillers | ||
| 28 | Main shoot and 8 tillers | ||
| 29 | Main shoot and 9 or more tillers | ||
| Stem Elongation | |||
| 30 | 4-5 | Pseudo stem erection | |
| 31 | 6 | 1st node detectable | |
| 32 | 7 | 2nd node detectable | |
| 33 | 3rd node detectable | ||
| 34 | 4th node detectable | ||
| 35 | 5th node detectable | ||
| 36 | 6th node detectable | ||
| 37 | 8 | Flag leaf just visible | |
| 39 | 9 | Flag leaf ligule/collar just visible | |
| Booting | |||
| 40 | - | ||
| 41 | 8-9 | Flag leaf sheath extending | |
| 45 | 10 | 9.2 | Boots just swollen |
| 47 | Flag leaf sheath opening | ||
| 49 | 10.1 | First awns visible | |
| Inflorescence emergence | |||
| 50 | 10.1 | 10.2 | First spikelet of inflorescence visible |
| 53 | 10.2 | 1/4 of inflorescence emerged | |
| 55 | 10.3 | 10.5 | 1/2 of inflorescence emerged |
| 57 | 10.4 | 10.7 | 3/4 of inflorescence emerged |
| 59 | 10.5 | 11.0 | Emergence of inflorescence completed |
| Anthesis | |||
| 60 | 10.51 | 11.4 | Beginning on anthesis |
| 65 | 11.5 | Anthesis half-way | |
| 69 | 11.6 | Anthesis completed | |
| Milk development | |||
| 70 | - | ||
| 71 | 10.54 | 12.1 | Kernel watery ripe |
| 73 | 13.0 | Early milk | |
| 75 | 11.1 | Medium milk | |
| 77 | Late milk | ||
| Dough development | |||
| 80 | - | ||
| 83 | 14.0 | Early dough | |
| 85 | 11.2 | Soft dough | |
| 87 | 15.0 | Hard dough | |
| Ripening | |||
| 90 | - | ||
| 91 | 11.3 | Kernel hard (difficult to divide with thumbnail) | |
| 92 | 11.4 | 16.0 | Kernel hard (no longer dented with thumbnail) |
| 93 | Kernel loosening in daytime | ||
| 94 | Overripe, straw dead and collapsing | ||
| 95 | Seed dormant | ||
| 96 | Viable seed giving 50% germination | ||
| 97 | Seed not dormant | ||
| 98 | Secondary dormancy induced | ||
| 99 | Secondary dormancy lost | ||
Another cereal development scale is the Feekes scale.
Read more about Zadoks Scale: Literature
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