Zadoks scale

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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.

Literature[edit]

  • J.C. Zadoks, T.T. Chang, C.F. Konzak, "A Decimal Code for the Growth Stages of Cereals", Weed Research 1974 14:415-421.

External links[edit]