The phenological growth stages and BBCH-identification keys of citrus plants are:
Growth stage | Code | Description | 0: Sprouting/Bud development | 00 | Dormancy: leaf and inflorescence buds undifferentiated, closed and covered by green scales |
01 | Beginning of bud swelling |
03 | End of bud swelling: green scales slightly separated |
07 | Beginning of bud burst |
09 | Green leaf tips visible |
1: Leaf development | 10 | First leaves separating: green scales slightly open, leaves emerging |
11 | First leaves visible[1] |
15 | More leaves visible, not yet at full size |
19 | First leaves fully expanded |
3: Shoot development | 31 | Beginning of shoot growth: axes of developing shoots visible |
32 | Shoots about 20% of final length |
39 | Shoots about 90% of final length |
5: Inflorescence emergence | 51 | Inflorescence buds swelling: buds closed, light green scales visible |
53 | Bud burst: scales separated, floral tips visible |
55 | Flowers visible, still closed (green bud), borne on single or multiflowered leafy or leafless inflorescences |
56 | Flower petals elongating; sepals covering half corolla (white bud) |
57 | Sepals open: petal tips visible; flowers with white or purplish petals, still closed |
59 | Most flowers with petals forming a hollow ball |
6: Flowering | 60 | First flowers open |
61 | Beginning of flowering: about 10% of flowers open |
65 | Full flowering: 50% of flowers open; first petals falling |
67 | Flowers fading: majority of petals fallen |
69 | End of flowering: all petals fallen |
7: Development of fruit | 71 | Fruit set; beginning of ovary growth; beginning of fruitlets abscission |
72 | Green fruit surrounded by sepal crown |
73 | Some fruits slightly yellow: beginning of physiological fruit drop |
74 | Fruits about 40% of final size. Dark green fruit: end of physiological fruit drop |
79 | Fruits about 90% of final size |
8: Maturity of fruit | 81 | Beginning of fruit colouring (colour-break) |
83 | Fruit ripe for picking; fruit has not yet developed variety-specific colour |
85 | Advanced ripening; increase in intensity of variety-specific colour |
89 | Fruit ripe for consumption; fruit has typical taste and firmness; beginning of senescence and fruit abscission |
9: Senescence, beginning of dormancy | 91 | Shoot growth complete; foliage fully green |
93 | Beginning of senescence and abscission of old leaves |
97 | Winter dormancy period |
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1. ^In Citrus the term "visible" replaces "unfolded" used for other fruit species. Leaf unfolding takes place precociously in citrus.