BBCH-scale (cotton)
Encyclopedia
In biology, the BBCH-scale for cotton describes the phenological
Phenology
Phenology is the study of periodic plant and animal life cycle events and how these are influenced by seasonal and interannual variations in climate...

 development of cotton plant
Cotton
Cotton is a soft, fluffy staple fiber that grows in a boll, or protective capsule, around the seeds of cotton plants of the genus Gossypium. The fiber is almost pure cellulose. The botanical purpose of cotton fiber is to aid in seed dispersal....

s Gossypium hirsutum using the BBCH-scale
BBCH-scale
The BBCH-scale is a scale used to identify the phenological development stages of a plant. A series of BBCH-scales have been developed for a range of crop species...

.

The phenological growth stages and BBCH-identification keys of cotton are:
Growth stageCodeDescription
0: Germination 00 Dry seed
01 Beginning of seed imbibition
Imbibition
'Imbibition' is defined as the displacement of one fluid by another immiscible fluid. This process is controlled and affected by a variety of factors...

03 Seed imbibition complete
05 Radicle
Radicle
In botany, the radicle is the first part of a seedling to emerge from the seed during the process of germination. The radicle is the embryonic root of the plant, and grows downward in the soil...

 emerged from seed
06 Elongation of radicle
07 Hypocotyl
Hypocotyl
The hypocotyl is the stem of a germinating seedling, found below the cotyledons and above the radicle .-Dicots:...

 with cotyledons breaking through seed coat
08 Hypocotyl with cotyledons growing towards soil surface
09 Emergence: hypocotyl with cotyledons breaking through soil surface (“crook stage”)
1: Leaf development (Main shoot) 10 Cotyledons completely unfolded1
11 First true leaf unfolded1
12 2nd true leaf unfolded1
13 3rd true leaf unfolded1
1 . Stages continuous till . . .
19 9 or more true leaves unfolded;1 no side shoots visible2
2: Formation of side shoots3 21 First vegetative side shoot (2nd order) visible
22 2 vegetative side shoots (2nd order) visible
23 3 vegetative side shoots (2nd order) visible
2 . Stages continuous till . . .
29 9 or more vegetative side shoots (2nd order) visible
3: Main stem elongation (Crop cover) 31 Beginning of crop cover: 10% of plants meet between rows
32 20% of plants meet between rows
33 30% of plants meet between rows
34 40% of plants meet between rows
35 50% of plants meet between rows
36 60% of plants meet between rows
37 70% of plants meet between rows
38 80% of plants meet between rows
39 Canopy closure: 90% of the plants meet between rows
5: Inflorescence
Inflorescence
An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Strictly, it is the part of the shoot of seed plants where flowers are formed and which is accordingly modified...

emergence (Main shoot)
51 First floral buds detectable (“pin-head square”)4
52 First floral buds visible (“match-head square”)4
55 Floral buds distinctly enlarged
59 Petals visible: floral buds still closed
6: Flowering 60 First flowers opened (sporadically within the population)
61 Beginning of flowering (“Early bloom”): 5–6 blooms / 25 ft of row (= 5–6 blooms / 7.5 meter of row)
65 Full flowering: (“Mid bloom”): 11 and more blooms / 25 ft of row = 11 and more blooms / 7.5 meter of row
67 Flowering finishing: majority of flowers faded (“Late bloom”)
69 End of flowering
7: Development of fruits and seeds 71 About 10% of bolls have attained their final size
72 About 20% of bolls have attained their final size
73 About 30% of bolls have attained their final size
74 About 40% of bolls have attained their final size
75 About 50% of bolls have attained their final size
76 About 60% of bolls have attained their final size
77 About 70% of bolls have attained their final size
78 About 80% of bolls have attained their final size
79 About 90% of bolls have attained their final size
8: Ripening of fruits and seeds 80 First open bolls on the first fruiting branches
81 Beginning of boll opening: about 10% of bolls open. Nodes Above White Flower (NAWF)
82 About 20% of bolls open
83 About 30% of bolls open. Nodes Above Cracked Boll (NACB)
84 About 40% of bolls open
85 About 50% of bolls open
86 About 60% of bolls open
87 About 70% of bolls open
88 About 80% of bolls open
89 About 90% of bolls open
9: Senescence 91 About 10% of leaves discoloured or fallen
92 About 20% of leaves discoloured or fallen
93 About 30% of leaves discoloured or fallen
94 About 40% of leaves discoloured or fallen
95 About 50% of leaves discoloured or fallen
96 About 60% of leaves discoloured or fallen
97 Above ground parts of plant dead; plant dormant
99 Harvested product (bolls and seeds)


1 Leaves are counted from the cotyledon node (= node 0)

2 Side shoot development may occur earlier, if there is a vegetative side shoot continue with principal growth stage 2. If there is a reproductive side shoot (fruiting branch) continue with the principal growth stage 5

3 Vegetative side shoots are counted from the cotyledon node

4 “pin-head square” or “match-head square” is the first square which forms at the first fruiting position of the first fruiting branch
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