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Comprehensive report of cumulative temperature (GDD) required for each growth stage of cucumber (Cucumis sativus-)
Overview
The growth of cucumbers is strongly influenced by the cumulative temperature (Growing Degree Days, GDD). Achieving a certain cumulative temperature at each growth stage (germination, seedling, flowering, fruiting) leads to the next growth stage. Based on the general cultivation conditions in Japan (outdoor cultivation and greenhouse cultivation), we will summarize the GDD value for each growth stage, its calculation basis, and calculation method using highly reliable Japanese literature and official materials.
Basics and calculation method of cumulative temperature (GDD)
For cucumbers, 10°C is generally adopted as the cumulative temperature standard (reference temperature, Tbase) in agricultural guidance and research in Japan.
The cumulative temperature is calculated by "subtracting Tbase from the average temperature of each day (and adding it to 0 if it is less than zero) every day."
- GDD = Σ [max(average temperature – 10, 0)]
The optimal temperature range varies depending on the growth stage, but the recommended temperature range is 25 to 30°C for germination, and 22 to 28°C for seedling to flowering and fruiting stages [1][2][3][4][5][6].
GDD value for each growth stage and calculation basis
1. Germination period (seeding to germination)
- Days: 3 to 10 days (from sowing to appearance of buds) [1][2][3][4][7]
- Optimal temperature range: 25-30°C
- GDD estimation: (e.g. average 28°C for 5 days)
(28 – 10) × 5 = 90°C/day - Actual width: 3-10 days around 28°C, estimated GDD is54-180°C/day
2. Seedling stage (germination - true leaf development)
- Days: 10 to 14 days (after germination, until seedlings have 2 to 4 true leaves) [1][2][4][5]< /li>
- Average temperature: 24-26°C
- GDD estimation: (e.g. average 25°C, 12 days)
(25 – 10) × 12 = 180°C/day
3. True leaf development-Blooming period (Seedling-Blooming from bud)
(25 – 10) × 31 = 465°C/day4. Flowering-Fruiting/Harvesting period (After flowering-Fruit harvesting)
- Number of days: 7 to 12 days (until fruit enlargement and harvest) [1][2][7][8][9]
- Average temperature: 22-28°C (assuming 25°C)
- GDD estimation: (e.g. average 25°C, 10 days)
(25 – 10) × 10 = 150°C/day - Japanese instruction manual/field information:
There are also descriptions that the cumulative temperature between "flowering and harvesting" is 200 to 300°C[8][9].
Summary of cumulative temperature by stage (estimated value)
| Estimated number of days between growth stages | Estimated number of days | Average temperature | Calculation formula | Estimated cumulative temperature (°C/day) | Main literature/sources |
|---|---|---|---|---|---|
| Seeding to germination | 3 to 10 | 25 to 30 | ( Tavg-10) x number of days | 54-180 | [1][2][3][4][7] |
| Germination ~ Seedling (true leaf development) | 10～14 | 24～26 | (Tavg-10) x number of days | 180 | [1][2][4][5] | Seedling to flowering (true leaf development to flowering) | 31 | 25 | (25-10)×31 | 465 | [1][2 ][7] |
| Sowing to flowering total | 40 to 55 | 25 | (25-10)×45 | 675< /td> | [1][2][7] |
| Flowering to fruiting (fruit harvest) | 7 to 12 | 25 | (25-10) ×10 | 150 | [1][2][8][9] |
| Japanese site standards (flower to harvest) | 200～300 | [8][9] |
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*The above is a standard greenhouse/outdoor cultivation model in Japan. The temperature may vary from 50 to 100°C depending on the region, variety, cultivation management method, etc., so adjustments should be made in conjunction with the local weather conditions and cultivation calendar [6][7][9].
Precautions for each cultivation environment
- Greenhouse cultivation
Temperature control is easy, so more planned integrated temperature control is possible. Even in the field, there are many cases in which the ``accumulated temperature required before harvest'' is used for work progress and harvest decisions [6][9]. - Outdoor cultivation
There is also the risk of delays in accumulation due to low temperature days due to daily temperature differences and bad weather. It is recommended to record and judge the accumulation using the local "average daily temperature" and an official calculation formula, rather than using an optimistic number of days.[4][6]
Basic/omitted value, and usage in Japanese literature/agricultural guidance
- Each integrated temperature value is described in JA, prefectural guidance, and breeding procedures for Takii seedlings, etc.[7][5] Explanations of cumulative temperature by research institutions and online calculation tools are also becoming widespread [6][9].
- Assumptions such as "standard temperature 10°C" and "average 25°C" are common in multiple Japanese official materials and cultivation manuals [5][6][7][9].
Practice of growth management using GDD
- By recording the daily average temperature immediately after sowing and integrating it using the reference temperature subtraction method, it is possible to flexibly predict the timing of germination, true leaf development, flowering, and harvest depending on the weather.
- By following the Japanese on-site guidance of ``harvesting at a cumulative temperature of 〇〇℃ after flowers bloom,'' you will not miss the optimal timing for fruit enlargement [8][9].
Overview
- The growth of cucumbers can be managed and predicted at each stage using "Gumulated Temperature (GDD)".
- Japan's standard value is Reference temperature 10°C, **Estimated GDD values for each growth stage (e.g. germination 54-180°C/day, seedling stage 180°C/day, seeding-flowering 675°C-day, flowering-harvest 200-300°C/day)** are used.
- Actual values vary depending on weather conditions, temperature control ability (outdoor/household), and variety, so it is best to use both predictions and actual measurements in the field.
- This cumulative temperature information is actually used and referenced in the Japanese official cultivation manual and on-site, and plays an important role as a reliable guideline for management and harvesting.
Sources
[1] Cucumber Growth Stages: How Fast Do Cucumbers Grow? https://www.epicgardening.com/cucumber-growth-stages/
[2] Cucumber Growth Stages: A Gardener's Guide to Success https://www.mars-hydro.com/info/post/cucumber-growth-stages
[3] Japanese Cucumber - GrowerTalks https://www.growertalks.com/Article/?articleid=16848
[4] Cucumber Life Cycle: A Comprehensive Guide for Gardeners https://growplant.org/blog/cucumber-life-cycle/
[5] Cucumber - Vegetable cultivation manual | Research - Takii seedlings https://www.takii.co.jp/tsk/manual/kyuuri.html
[6] Introducing the vegetable garden navigation function "cumulative temperature calculator"! https://matome.saien-navi.jp/archives/3662
[7] Is summer the best time to grow cucumbers? About cultivation seasons and cropping types - Farmer web https://www.noukaweb.com/cucumber-cultivation-seasons/
[8] List of cumulative temperatures required for each vegetable cultivation crop until harvest - Habesta https://harvest-timer.com/temperature/
[9] When should I plant cucumbers for autumn harvest? - Yahoo! Chiebukuro https://detail.chiebukuro.yahoo.co.jp/qa/question_detail/q11317293781