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In biology, the BBCH-scale for peanut describes the phenological development of peanuts using the BBCH-scale.
Phenology is the study of periodic plant and animal life cycle events and how these are influenced by seasonal and interannual variations in climate, as well as habitat factors. The word, coined by the Belgian botanist Charles Morren around 1849, is derived from the Greek φαίνω (phainō), "to show, to bring to light, make to appear" + λόγος (logos), amongst others "study, discourse, reasoning" and indicates that phenology has been principally concerned with the dates of first occurrence of biological events in their annual cycle. Examples include the date of emergence of leaves and flowers, the first flight of butterflies and the first appearance of migratory birds, the date of leaf colouring and fall in deciduous trees, the dates of egg-laying of birds and amphibia, or the timing of the developmental cycles of temperate-zone honey bee colonies. In the scientific literature on ecology, the term is used more generally to indicate the time frame for any seasonal biological phenomena, including the dates of last appearance.
The peanut, also known as the groundnut, goober, or monkey nut (UK), and taxonomically classified as Arachis hypogaea, is a legume crop grown mainly for its edible seeds. It is widely grown in the tropics and subtropics, being important to both small and large commercial producers. It is classified as both a grain legume and, due to its high oil content, an oil crop. World annual production of shelled peanuts was 44 million tonnes in 2016, led by China with 38% of the world total. Atypically among crop plants, peanut pods develop underground (geocarpy) rather than aboveground. With this characteristic in mind, the botanist Linnaeus named the species hypogaea, which means "under the earth."
The BBCH-scale is used to identify the phenological development stages of plants. BBCH-scales have been developed for a range of crop species where similar growth stages of each plant are given the same code.
The phenological growth stages and BBCH-identification keys of peanuts are:
| Growth stage | Code | Description |
|---|---|---|
| 0: Germination | 00 | Dry seed |
| 01 | Beginning of seed imbibition | |
| 03 | Seed imbibition complete | |
| 05 | Radicle emerged from seed | |
| 07 | Hypocotyl with cotyledons breaking through seed coat | |
| 08 | Hypocotyl reaches the soil surface; hypocotyl arch visible | |
| 09 | Emergence: hypocotyl with cotyledons arising above soil surface (“cracking stage”) | |
| 1: Leaf development (main shoot) | 10 | Cotyledons completely unfolded1 |
| 11 | First true leaf (pinnate) unfolded1 | |
| 12 | 2nd true leaf (pinnate) unfolded1 | |
| 13 | 3rd true leaf (pinnate) unfolded1 | |
| 1 . | Stages continuous till . . . | |
| 19 | 9 or more true leaves unfolded.1 No side shoots visible2 | |
| 2: Formation of side shoots3 | 21 | 1st side shoot visible |
| 22 | 2nd side shoot visible | |
| 23 | 3rd side shoot visible | |
| 2 . | Stages continuous till . . . | |
| 29 | 9 or more side shoots visible | |
| 3: Main stem elongation (Crop cover) | 31 | Beginning of crop cover: 10% of plants meets between rows |
| 32 | 20% of plants meets between rows | |
| 33 | 30% of plants meets between rows | |
| 34 | 40% of plants meets between rows | |
| 35 | 50% of plants meets between rows | |
| 36 | 60% of plants meets between rows | |
| 37 | 70% of plants meets between rows | |
| 38 | 80% of plants meets between rows | |
| 39 | Crop cover complete: 90% of plants meets between rows | |
| 5: Inflorescence emergence | 51 | First inflorescence buds visible |
| 55 | First individual flower buds visible | |
| 59 | First flower petals visible. Flower buds still closed | |
| 6: Flowering | 61 | Beginning of flowering |
| 62 | First carpophore pegs visible | |
| 63 | Continuation of flowering | |
| 64 | First carpophore pegs visibly elongated | |
| 65 | Full flowering | |
| 66 | First carpophore pegs penetrating the soil | |
| 67 | Flowering declining4 | |
| 68 | Tip of first carpophore pegs growing horizontally in the soil | |
| 69 | End of flowering4 | |
| 7: Development of fruits and seeds | 71 | Beginning of pod development: tip of first carpophore pegs swollen (at least twice the original diameter) |
| 73 | Continuation of pod development: beginning of pod filling: first pods have attained final size and are ripening | |
| 75 | Main phase of pod development: continuation of pod filling | |
| 77 | Advanced pod filling | |
| 79 | Fresh seeds fill the cavity of the pods which have attained their final size | |
| 8: Ripening of fruits and seeds5 | 81 | Beginning of ripening: about 10% of pods developed to final size are ripe |
| 82 | About 20% of pods developed to final size are ripe | |
| 83 | Continuation of ripening: about 30% of pods developed to final size are ripe | |
| 84 | About 40% of pods developed to final size are ripe | |
| 85 | Main phase of ripening: about 50% of pods developed to final size are ripe | |
| 86 | About 60% of pods developed to final size are ripe | |
| 87 | Advanced ripening: about 70% of pods developed to final size are ripe | |
| 88 | About 80% of pods developed to final size are ripe | |
| 89 | Full maturity: nearly all pods developed to final size are ripe | |
| 9: Senescence | 91 | About 10% of above ground parts of plant dry |
| 92 | About 40% of above ground parts of plant dry | |
| 93 | About 30% of above ground parts of plant dry | |
| 94 | About 40% of above ground parts of plant dry | |
| 95 | About 50% of above ground parts of plant dry | |
| 96 | About 60% of above ground parts of plant dry | |
| 97 | Above ground parts of plant dead | |
| 99 | Harvested product |
1 Leaves are counted from the cotyledon node (= node 0)
2 Side shoot development may occur earlier; in this case continue with principal growth stage 2
4 Only for varieties with a determinate flowering period
5 Criteria of maturity: Pericarp hard, with distinct texture, can be split open easily;
