{ "id": "germination-and-seedlings", "url": "https://coffearium.org/entries/germination-and-seedlings/", "license": "CC-BY-4.0", "title": "Germination and seedlings", "summary": "How a coffee seed takes up water, weakens the endosperm in front of its root, pushes out a radicle and lifts its seed leaves above the soil – and why this takes weeks rather than days.", "domain": "botany", "kind": "Process", "stage": "plant", "topics": [ "science" ], "topicSections": {}, "lang": "en", "status": "verified", "reviewer": "Coffearium verification pass", "lastVerified": "2026-10-22T00:00:00.000Z", "updated": "2026-10-22T00:00:00.000Z", "added": "2026-10-22T00:00:00.000Z", "brief": [ "Coffee germinates slowly and unevenly; in the laboratory, without parchment at 30 °C, the first radicles appear after 5 days and half the seeds have germinated by day 10.1,3", "The radicle can only emerge after the endosperm in front of it weakens, in two steps; the second step goes with endo-β-mannanase activity.1,2", "Germination is epigeal – the hypocotyl lifts the seed out of the soil (the matchstick stage) and the cotyledons then unfold (the butterfly stage).1,6", "In the field, arabica seedlings start to emerge 50–60 days after sowing in warm periods and up to 90 days when it is cooler.1", "The parchment slows germination; Colombian guidance gives 50–70 days for seed sown in parchment and 20 days less without it.1,7" ], "quickFacts": [ { "label": "Germination type", "value": "Epigeal (cotyledons above the soil)" }, { "label": "Radicle protrusion, lab", "value": "From day 5; 50% by day 10 (30 °C, no parchment)" }, { "label": "Emergence from soil", "value": "50–60 days (warm) to 90 days (cool)" }, { "label": "Cotyledons fully open", "value": "About 9 weeks after sowing (BBCH, 23/17 °C)" }, { "label": "Growth-stage codes", "value": "BBCH 00–09 (germination), 10–19 (leaves)" } ], "aka": [ "Coffee seed germination" ], "linkTerms": [ "seed germination", "coffee seedling", "seedling", "radicle", "hypocotyl", "cotyledon", "matchstick stage", "butterfly stage", "chapola", "endosperm cap" ], "related": [ "seed-anatomy-and-storage", "coffee-cherry-anatomy", "coffea-arabica", "fruit-development", "drying", "natural-process" ], "contested": [ "How long seed stays fit to sow: a 2006 review says arabica viability falls quickly after 4–6 months at ambient temperature1; a Laos manual says seed loses viability within three months and advises storing it in cool, moist conditions6; Colombian guidance gives an average life of 6 months under suitable storage7; and a 2021 Colombian storage trial kept emergence above 75% for the first six months at 7.5 °C and 10 °C, but only four months at 25 °C.10 The figures depend on storage temperature, humidity and seed moisture, which the sources set differently.", "Timing of germination activity in natural processing: in a 2006 study, isocitrate lyase expression and β-tubulin in the embryo peaked 4–5 days after the start of dry processing12; a 2007 study by the same research group put the maximum at about one week.11 Both agree that the peak in washed processing comes about 2 days after the start.11,12" ], "corrections": [ { "date": "2026-10-22T00:00:00.000Z", "change": "Removed the embryo-growth figure (1.06 mm, 35% in 10 days) and the thesis quote that carried it.", "reason": "The number is in the 2002 thesis chapter, which is the unpublished manuscript of the 2004 Planta paper rather than a reprint; the Planta abstract does not give it and its full text could not be opened." }, { "date": "2026-10-22T00:00:00.000Z", "change": "The 37 °C limit is now described as the limit for mechanical drying of seed for sowing, not a germinator temperature.", "reason": "The Colombian chapter gives 37 °C for drying the seed, not for the germinator." }, { "date": "2026-10-22T00:00:00.000Z", "change": "Removed \"in Brazil\" from the 50–60 and 90 day emergence values; the claim is now attributed to the 2006 review citing a 1961 study.", "reason": "The review does not name a country for these values." }, { "date": "2026-10-22T00:00:00.000Z", "change": "Removed the 2006 Plant Biology paper; its statements now rest on the 2007 Annals of Botany study (source 11).", "reason": "The 2006 paper could not be opened from this environment, and the 2007 study states the same findings." }, { "date": "2026-10-22T00:00:00.000Z", "change": "Restored the embryo-growth figure (1.06 mm, 35% of initial length, by day 10 of imbibition), now cited to the 2004 Planta paper, and added its puncture-force, imbibition, pressure-potential and ABA timings.", "reason": "The owner supplied the paper's full text, which gives these values; the paper was previously cited from its abstract only." }, { "date": "2026-10-22T00:00:00.000Z", "change": "Re-added the 2006 Plant Biology paper (isocitrate lyase and β-tubulin timings during washed and natural processing) and added a 2017 review on germination during processing; new contested item on the timing in natural processing.", "reason": "The owner supplied both full texts." } ], "sources": [ { "id": "s1", "title": "Coffee seed physiology", "authors": "Eira, M. T. S.; Amaral da Silva, E. A.; De Castro, R. D.; Dussert, S.; Walters, C.; Bewley, J. D.; Hilhorst, H. W. M.", "year": 2006, "publisher": "Brazilian Journal of Plant Physiology 18(1), 149–163", "url": "https://www.scielo.br/j/bjpp/a/zZgRS3Mbwg8KjW8R9bn9X3L", "doi": "10.1590/S1677-04202006000100011", "tier": "A", "quote": "C. arabica seedling emergence from the soil starts 50 to 60 days after sowing in the warmer periods of the year", "accessed": "2026-10-22T00:00:00.000Z" }, { "id": "s2", "title": "Abscisic acid controls embryo growth potential and endosperm cap weakening during coffee (Coffea arabica cv. Rubi) seed germination", "authors": "da Silva, E. A. A.; Toorop, P. E.; van Aelst, A. C.; Hilhorst, H. W. M.", "year": 2004, "publisher": "Planta 220, 251–261", "url": "https://www.doi.org/10.1007/s00425-004-1344-0", "doi": "10.1007/s00425-004-1344-0", "tier": "A", "quote": "The increase in embryo length was 1.06 mm (35% of initial length) until 10 days of imbibition (P<0.01).", "accessed": "2026-10-22T00:00:00.000Z" }, { "id": "s3", "title": "Expression studies in the embryo and in the micropylar endosperm of germinating coffee (Coffea arabica cv. Rubi) seeds", "authors": "de Farias, E. T.; Amaral da Silva, E. A.; Toorop, P. E.; Bewley, J. D.; Hilhorst, H. W. M.", "year": 2015, "publisher": "Plant Growth Regulation 75(2), 575–581", "url": "https://link.springer.com/article/10.1007/s10725-014-9960-6", "doi": "10.1007/s10725-014-9960-6", "tier": "A", "quote": "The first seed germinated after 5 days of imbibition and 50 % germination was reached after 10 days.", "abstractOnly": true, "accessed": "2026-10-22T00:00:00.000Z" }, { "id": "s4", "title": "Coffee (Coffea arabica cv. Rubi) seed germination: mechanisms and regulation", "authors": "da Silva, E. A. A.", "year": 2002, "publisher": "Doctoral thesis, Wageningen University", "url": "https://edepot.wur.nl/192247", "doi": "10.18174/192247", "tier": "B", "tierNote": "Doctoral thesis (B), cited only for statements without numbers. Chapter 3 is the manuscript of the study later published as source 2 (same authors, same abstract), but it predates that paper and carries no publication note, so it is not treated as a reprint and none of its numbers are used.", "quote": "The coffee embryo grows first by increase in cell width followed by longitudinal growth.", "accessed": "2026-10-22T00:00:00.000Z" }, { "id": "s5", "title": "Application of the 'Extended BBCH-Scale' for the description of the growth stages of coffee (Coffea sp.)", "authors": "Arcila-Pulgarín, J.; Buhr, L.; Bleiholder, H.; Hack, H.; Wicke, H.", "year": 2001, "publisher": "Cenicafé, Boletín Técnico No. 23", "url": "https://publicaciones.cenicafe.org/index.php/bot/article/download/1322/3134/2901", "tier": "A", "quote": "After three weeks radicle protrusion and hooking are visible (stage 05).", "accessed": "2026-10-22T00:00:00.000Z" }, { "id": "s6", "title": "Arabica coffee manual for Lao PDR", "authors": "Winston, E.; Op de Laak, J.; Marsh, T.; Lempke, H.; Chapman, K.", "year": 2005, "publisher": "FAO Regional Office for Asia and the Pacific, Bangkok", "url": "https://www.fao.org/4/ae939e/ae939e04.htm", "tier": "A", "quote": "Transplant coffee when it is at the matchstick or cotyledon (butterfly) stage before the taproot is well developed", "accessed": "2026-10-22T00:00:00.000Z" }, { "id": "s7", "title": "Germinadores de café [Coffee germinators]. In: Manual del cafetero colombiano, Tomo 2", "authors": "Rivillas Osorio, C. A.; Gaitán Bustamante, Á. L.", "year": 2013, "publisher": "Federación Nacional de Cafeteros de Colombia; Cenicafé", "url": "https://biblioteca.cenicafe.org/jspui/bitstream/10778/4326/1/cenbook-0026_14.pdf", "tier": "A", "quote": "Las semillas que presenten pergamino (endocarpio) germinarán entre 50 y 70 días", "accessed": "2026-10-22T00:00:00.000Z" }, { "id": "s8", "title": "Almácigos de café: calidad fitosanitaria, manejo y siembra en el campo [Coffee nurseries: plant health, management and field planting]", "authors": "Gaitán B., Á. L.; Villegas G., C.; Rivillas O., C. A.; Hincapié G., É.; Arcila P., J.", "year": 2011, "publisher": "Cenicafé, Avances Técnicos No. 404", "url": "https://biblioteca.cenicafe.org/jspui/bitstream/10778/350/1/avt0404.pdf", "tier": "A", "quote": "sus dos hojas cotiledonares están completamente extendidas", "accessed": "2026-10-22T00:00:00.000Z" }, { "id": "s9", "title": "Effect of Temperature on Arabica Coffee", "authors": "Tummakate, A.", "year": 1991, "publisher": "Thai Agricultural Research Journal 9(1), 55–61", "url": "https://li01.tci-thaijo.org/index.php/thaiagriculturalresearch/article/view/242210", "tier": "A", "quote": "Seed germination was found to take only three week at 30 C constantly", "abstractOnly": true, "accessed": "2026-10-22T00:00:00.000Z" }, { "id": "s10", "title": "Efecto del almacenamiento en la viabilidad, germinación y vigor de semillas de Coffea arabica L. [Effect of storage on the viability, germination and vigour of Coffea arabica seeds]", "authors": "Flechas Bejarano, N. C.; Medina Rivera, R. D.", "year": 2021, "publisher": "Revista Cenicafé 72(2), e72206", "url": "https://cenicafe.org/es/publications/arc072%2802%29e72206.pdf", "doi": "10.38141/10778/72206", "tier": "A", "quote": "mantuvieron su probabilidad de emergencia mayor al 75% durante los primeros seis meses", "accessed": "2026-10-22T00:00:00.000Z" }, { "id": "s11", "title": "Transient occurrence of seed germination processes during coffee post-harvest treatment", "authors": "Bytof, G.; Knopp, S.-E.; Kramer, D.; Breitenstein, B.; Bergervoet, J. H. W.; Groot, S. P. C.; Selmar, D.", "year": 2007, "publisher": "Annals of Botany 100(1), 61–66", "url": "https://academic.oup.com/aob/article/100/1/61/2763338", "doi": "10.1093/aob/mcm068", "tier": "A", "quote": "The highest germination activity occurred 2 d after the onset of wet processing, whereas the corresponding maximum in the course of dry processing appeared about 1 week after the start of post harvest treatment.", "accessed": "2026-10-22T00:00:00.000Z" }, { "id": "s12", "title": "Germination of Coffee Seeds and its Significance for Coffee Quality", "authors": "Selmar, D.; Bytof, G.; Knopp, S.-E.; Breitenstein, B.", "year": 2006, "publisher": "Plant Biology 8(2), 260–264", "url": "https://onlinelibrary.wiley.com/doi/10.1055/s-2006-923845", "doi": "10.1055/s-2006-923845", "tier": "A", "quote": "In wet-processed seeds, significant ICL expression was already observed on the first day of processing.", "accessed": "2026-10-22T00:00:00.000Z" }, { "id": "s13", "title": "Overview on the mechanisms of coffee germination and fermentation and their significance for coffee and coffee beverage quality", "authors": "Waters, D. M.; Arendt, E. K.; Moroni, A. V.", "year": 2017, "publisher": "Critical Reviews in Food Science and Nutrition 57(2), 259–274", "url": "https://www.tandfonline.com/doi/full/10.1080/10408398.2014.902804", "doi": "10.1080/10408398.2014.902804", "tier": "A", "tierNote": "Peer-reviewed review (A); cited only for its own synthesis and assessments, not for numbers from the studies it reviews.", "quote": "However, to date, there are only a limited number of studies that clearly link specific biochemical changes in the developing bean with specific alterations in the sensory attributes of coffees.", "accessed": "2026-10-22T00:00:00.000Z" } ], "markdown": "## What germination is\n\nGermination is the step from a resting seed to a growing plant. It ends when the radicle, the embryonic root, breaks out of the seed.1,3 Everything after that is seedling growth.\n\nA coffee seed is mostly endosperm, a hard storage tissue. Its walls are built of cellulose and hemicelluloses, mainly insoluble mannans.1 The embryo is small: 3–4 mm long, an axis with two heart-shaped cotyledons, or seed leaves.1 The part of the endosperm in front of the root tip is called the endosperm cap.1 See [Seed anatomy and storage](/entries/seed-anatomy-and-storage/) for the seed itself.\n\nCoffee germinates slowly and unevenly.1,3 Seed for planting is sown in its parchment, the shell around each seed.6 The parchment holds germination back strongly, so laboratories remove it before germination tests.1\n\n## From seed to seedling, stage by stage\n\n
\n
\n
    \n
  1. Imbibition: the seed takes up water and swells. In the BBCH growth-stage scale, imbibition is complete about one week after germination starts.5
    2. \n
  2. Radicle protrusion: the endosperm cap gives way and the radicle emerges and bends downwards; in the field, after about three weeks.1,5,6
    3. \n
  3. Root growth: the radicle lengthens and forms root hairs and lateral roots.5,6
    4. \n
  4. Matchstick (Spanish fósforo): the hypocotyl, the stem below the seed leaves, carries the seed in its parchment out of the soil.5,6,8
    5. \n
  5. Butterfly (Spanish chapola): the parchment falls away and the two cotyledons unfold.6,8
    6. \n
  6. First true leaves: the terminal bud opens the first pair of leaves above the cotyledons.5,6
    7. \n
\n
Six stages from the sown seed to the first true leaves. Point at a stage, its number or its name to highlight it. Schematic, not to scale.
\n
\n\nWater comes first. The seed absorbs water, swells and turns whitish.5 Then the embryo grows inside the seed, and the endosperm cap in front of the root tip softens.1,3 When the cap gives way, the radicle breaks through and turns downwards.1,5\n\nCoffee germination is epigeal: the seed leaves rise above the soil.1 The hypocotyl grows upwards and lifts the seed, still in its parchment, out of the ground.6 Nursery manuals call this the matchstick stage.6,8 Shortly afterwards the parchment drops and the two cotyledons open: the butterfly stage.6\n\nThe cotyledons look quite unlike adult leaves. They are oval, with wavy edges, and 20–50 mm across.6 After germination they grow by absorbing the endosperm, which takes them 3–4 weeks.1 Then the terminal bud opens the first pair of true leaves, opposite each other.6 Their nutritional role done, the cotyledons later die.6\n\n## How long it takes\n\nLaboratory tests remove the parchment and keep the seeds at 30 °C in the dark. Under these conditions the first radicles appear around day 5–6, half the seeds have germinated by day 10, and most by day 15.1,2,3\n\nIn soil, with the parchment on, it takes weeks. A Colombian growth-stage bulletin describes the radicle after three weeks, about 90% of seedlings above ground at seven weeks and fully open cotyledons at nine.5 A 2006 review, citing a 1961 study, gives the start of arabica emergence as 50–60 days after sowing in the warmer periods of the year. In cooler periods this can stretch to 90 days.1\n\n
\n
\n
Days to each stage as reported by each source. Conditions differ between rows: laboratory or field, constant or seasonal temperature, with or without parchment. Single points are values given in weeks or months, converted to days by us.1,2,3,5,6,7,9
\n
\n\nTemperature sets the pace. A 1991 Thai paper on temperature and arabica gives about three weeks at a constant 30 °C and about three months at 17 °C.9 A coffee manual for Laos gives 30–50 days before shoots appear, depending on soil temperature.6 Colombian guidance gives 50–70 days for seed in parchment and 20 days less without it.7\n\nSeed age matters too. Coffee seed does not keep for long, and older seed germinates less well (see Contested).1,6,7,10 Raising seedlings for planting is covered on the [Farm stage](/explore/farm/), under nurseries.\n\n\n\n## Inside the seed: embryo against endosperm\n\nGermination in coffee is a contest between the embryo's push and the endosperm cap's resistance.1,2 The lateral endosperm is extremely hard, because mannan is laid down there as thick cell walls.1 The cap in front of the radicle is the only route out.\n\n**The embryo grows before the radicle emerges.** In a 2004 study on cv. Rubi (parchment removed, 30 °C, dark), the embryo grew inside the endosperm before radicle protrusion. Its length increased by 1.06 mm, 35% of its initial length, up to day 10 of imbibition.2 The axis grew by about 0.73 mm (36%) and the cotyledons by 0.33 mm (34%), but the cotyledons grew only during the first 5 days.2 The embryo's pressure potential rose from 0.11 MPa at day 2 to 1.62 MPa at day 5 and fell to around 0 MPa at day 6; the authors read this as cell-wall relaxation that allows further growth.2 According to a doctoral thesis from the same group, the embryo first grows in width, then in length, and cell division starts before radicle protrusion.4 A 2015 study confirmed that the embryo grows inside the seed before the radicle protrudes.3\n\n**The cap weakens in two steps.** Measurements of the force needed to puncture the cap show a first decrease, then a second.1,2 In the 2004 study the force fell from 1.36 N at day 2 to 0.57 N at day 9, with the first phase between days 0 and 4 and the second between days 6 and 9.2 A rise in cellulase activity coincided with the first step and a rise in endo-β-mannanase activity with the second.2 Endo-β-mannanase activity was detectable in the cap from day 2 and appeared there before it appeared in the rest of the endosperm.2,4 Earlier studies disagreed on whether this enzyme acts before radicle protrusion at all; a 2017 review notes that the method of one early study may not have been sensitive enough to detect low activity.13 Gene expression of β-mannosidase and endo-β-mannanase increases during imbibition.3\n\n## Hormones: ABA and gibberellins\n\nAbscisic acid (ABA) slows coffee germination at two points. It reduces the embryo's growth potential and blocks the second step of cap weakening, together with endo-β-mannanase activity in the cap.1,2 In that study, 1,000 µM ABA prevented germination completely; the puncture force stopped falling after day 7 and endo-β-mannanase activity in the cap stayed below 10% of the water control.2 The embryo's own ABA content rose at day 2 of imbibition and peaked again around day 5, then fell to near zero at day 8, when radicles protruded.2 Fluridone, which blocks ABA synthesis, shortened the time to 50% germination from 9.9 to 8.9 days. The authors conclude that ABA is made anew in the embryo during imbibition and that this may contribute to the slow rate of radicle protrusion.2 ABA inhibits both embryo growth and radicle protrusion; α-galactosidase expression is less affected by it.3\n\nGibberellins (GAs) are needed: endogenous GAs are required for embryo cell elongation and for cap weakening.1 Applied GA3, by contrast, inhibits radicle protrusion in coffee.1\n\n## Growth stages on the BBCH scale\n\nThe extended BBCH scale gives every stage a two-digit code. Cenicafé, the Colombian coffee research centre, published the coffee version in 2001.5 Its timings are written for average ambient conditions of 23 °C by day and 17 °C by night.5\n\n| Code | Stage | Timing (bulletin, 23/17 °C) |\n|---|---|---|\n| 00 | Dry seed, 11–12% moisture (basis not stated); beige in parchment | At sowing |\n| 01–03 | Imbibition: seed swollen, whitish, no radicle | Complete after about 1 week |\n| 05 | Radicle protrusion and hooking | About 3 weeks |\n| 06 | Radicle lengthens; root hairs and lateral roots | – |\n| 07–09 | Hypocotyl breaks through the seed coat; seedling emerges with cotyledons still enclosed in the parchment | Nearly 90% emerged at about 7 weeks |\n| 10 | Cotyledons completely unfolded; first pair of true leaves separating | About 9 weeks |\n| 11–19 | One to nine or more leaf pairs unfolded | – |\n\nSource for the table: Arcila-Pulgarín et al. 2001.5 We group neighbouring codes where the bulletin's descriptions overlap.\n\n## Reference values\n\n| Parameter | Value | Source |\n|---|---|---|\n| Embryo length (mature seed) | 3–4 mm | Eira et al.1 |\n| Embryo growth before radicle protrusion (cv. Rubi, lab) | +1.06 mm (35% of initial length) by day 10 | da Silva et al.2 |\n| Water uptake, lab (cv. Rubi, no parchment, 30 °C) | Plateau (phase II) from day 3 to day 15, then a second rise | da Silva et al.2 |\n| Force to puncture the endosperm cap, lab | 1.36 N at day 2; 0.57 N at day 9 | da Silva et al.2 |\n| Radicle protrusion, lab (no parchment, 30 °C, dark) | Starts day 5–6; 50% by day 10; most by day 15 | Eira et al.1; da Silva et al.2; de Farias et al.3 |\n| Germination, constant temperature | ≈3 weeks at 30 °C; ≈3 months at 17 °C | Tummakate9 |\n| Radicle visible, field | ≈3 weeks; 3–4 weeks | Arcila-Pulgarín et al.5; Winston et al.6 |\n| Emergence from soil (*C. arabica*) | Starts at 50–60 days (warm periods); up to 90 days (cool) | Eira et al.1 |\n| Germination in parchment, Colombian germinator | 50–70 days; 20 days less without parchment | Rivillas Osorio & Gaitán Bustamante7 |\n| Cotyledons absorb the endosperm | 3–4 weeks | Eira et al.1 |\n| Cotyledon size | Oval, wavy-edged, 20–50 mm across | Winston et al.6 |\n| Mechanical drying of seed for sowing, temperature limit (Colombian guidance) | Never above 37 °C | Rivillas Osorio & Gaitán Bustamante7 |\n| Time in the germinator to butterfly stage | 75–80 days | Rivillas Osorio & Gaitán Bustamante7 |\n\n## Light, parchment and seed age\n\n**Parchment.** The endocarp drastically inhibits coffee germination.1 The Colombian figure of 20 days saved without parchment is a practical guide value, not a controlled comparison.7\n\n**Light.** Colombian guidance states that light inhibits root formation and delays germination.7 No controlled study of light and coffee germination was opened for this entry.\n\n**Seed age and storage.** Coffee seed has intermediate storage behaviour: it does not survive complete drying, or drying combined with cold.1 In a 2021 Colombian trial with var. Castillo, seed stored at 7.5 °C or 10 °C kept an emergence probability above 75% for six months; at 25 °C, for four months.10 The sources give different keeping times (see Contested). Storage itself is covered in [Seed anatomy and storage](/entries/seed-anatomy-and-storage/).\n\n## Germination during processing\n\nThe seed is alive in the cherry and in processing. Studies in 2006 and 2007 showed that germination processes start in coffee seeds during standard post-harvest treatment.11,12 In the 2006 study, fresh ripe cherries from Brazil or Tanzania were processed both ways in the laboratory. It used two markers: expression of isocitrate lyase, a germination-specific enzyme of the glyoxylate cycle, and β-tubulin in the embryo, a marker of resumed cell division.12 Fresh seeds showed no or only minor signals of either.12\n\nIn washed processing, isocitrate lyase expression was clear on the first day and highest on the second, when fermentation ended; it fell rapidly during drying.12 In natural processing, clear signals appeared after 2–3 days and peaked at days 4–5; β-tubulin followed the same pattern.12 The 2007 study put the natural-process maximum at about one week (see Contested).11 The authors propose that ABA and the osmotic potential of the fruit flesh hold germination back inside the fruit, and that removing the pulp lifts this brake.12 A 2017 review reads the earlier start in washed processing the same way.13\n\nThe authors link these differences to differences in green-coffee chemistry and quality.11,12 See [Drying](/entries/drying/) and [Coffee cherry anatomy](/entries/coffee-cherry-anatomy/).\n\n## Open questions\n\n- **Canephora seedlings.** Almost all the mechanistic work cited here used *C. arabica*, mostly cv. Rubi. No study opened for this entry measured germination timing for *C. canephora*.\n- **Temperature response.** No study opened for this entry gives a full germination curve across temperatures with stated minimum, optimum and maximum. The 30 °C and 17 °C values come from a paper abstract that does not name the underlying trials.9\n- **Why ABA rises during imbibition.** The 2004 study showed that the embryo makes ABA during imbibition and suggests that this slows germination; what triggers the synthesis is not established.2\n- **Fresh versus re-imbibed seed.** The 2006 study and a 2017 review note that most coffee germination studies used dried seed soaked again, not fresh seed from the fruit, so they may mix arrested and new germination.12,13 The 2004 laboratory study also used seed dried to 12% moisture (fresh-weight basis).2\n- **From germination to the cup.** The 2006 study states that a clear chain of cause and effect from processing biochemistry to coffee quality is still lacking; a 2017 review finds only a limited number of studies linking specific biochemical changes to specific sensory attributes.12,13\n\n## Key studies\n\n
\n

Eira et al., 2006 – Coffee seed physiology. A review of coffee seed development, germination and storage. It sets out the hard mannan endosperm, the two-step weakening of the endosperm cap, the roles of ABA and gibberellins, epigeal emergence and intermediate storage behaviour.

\n

Brazilian Journal of Plant Physiology 18(1), 149–163 · doi:10.1590/S1677-04202006000100011

\n
\n\n
\n

da Silva et al., 2004 – ABA, embryo growth and the endosperm cap. Germinated cv. Rubi seeds with and without ABA and followed embryo growth potential, endosperm cap weakening and enzyme activity. The embryo grew by 35% in length before the radicle emerged, and the cap weakened in two steps; ABA blocked the second step and the endo-β-mannanase activity in the cap, but not cellulase.

\n

Planta 220, 251–261 · doi:10.1007/s00425-004-1344-0

\n
\n\n
\n

de Farias et al., 2015 – Gene expression in embryo and cap. Followed genes for the cell cycle and cell-wall enzymes during germination of cv. Rubi. The embryo grew before the radicle emerged; mannan-degrading enzyme genes rose during imbibition, and ABA slowed both embryo growth and protrusion.

\n

Plant Growth Regulation 75(2), 575–581 · doi:10.1007/s10725-014-9960-6

\n
\n\n
\n

Arcila-Pulgarín et al., 2001 – BBCH scale for coffee. A Cenicafé bulletin that describes coffee growth stages on the extended BBCH scale, from dry seed to ripe fruit, with typical timings under average Colombian conditions.

\n

Cenicafé Boletín Técnico 23 · Cenicafé library

\n
\n\n
\n

Bytof et al., 2007 – Germination during processing. Followed germination markers to show that germination processes start in the seed during post-harvest treatment. Activity peaked about two days into wet processing and about a week into dry processing.

\n

Annals of Botany 100(1), 61–66 · doi:10.1093/aob/mcm068

\n
" }