Does Soybean Photoperiod Sensitivity Impact Variety Selection?

Apr 08, 2020

There are two distinct growth stages in many crops; the vegetative and reproductive stages. In soybeans the vegetative stage usually lasts between 30 to 50 days after emergence. Once a flower appears on the plant the reproductive phase has begun. What makes soybean unique is that vegetative growth (leaf number, node number, and dry weight) continues as flowers are formed. Flowering is triggered by day length although temperature also plays an important role. Soybeans are therefore called “photoperiod sensitive”. “Photoperiod” is a term that simply means the period each day during which a plant receives illumination (day length).

Soybean flowering is initiated as the days get shorter which is after the summer solstice on June 21st. Under ideal growing conditions, early planted soybeans can begin flowering before the summer solstice but do not ramp up to full flower until later. The initiation of flowering is not the only impact of photoperiod on soybeans. Many of the reproductive phases of the plant are also impacted by day length. The effect also seems to be cumulative, the shorter the days get, the faster the soybean plant will go through its growth stages. A Wisconsin study showed that the time spent from the R1 growth stage (first flower) to R6 (full seed) was much shorter for late planted soybeans compared to an early planting. Soybeans planted May 1st spent 60 days from the R1 to R6 growth stage while the same varieties planted June 1st spent only 45 days going through the same growth stages.

How fast a soybean plant goes through its growth stages will depend not only on day length but is also impacted by moisture, plant health, and temperature. This means the length of time it will take for a soybean plant to mature is not as easy to predict as other crops like corn. The variety, environment, day length, and planting date interact to determine the number of days necessary to reach maturity. Therefore, there is no accurate chart that assigns a precise number of days from first flower to physiological maturity. Photoperiod sensitivity also means the plant can adjust to the season or “catch up” when planting is delayed. The photoperiod and temperature drives soybeans to mature more quickly as the days shorten in the fall.

Click here to see more...

Video: Will the 2025 USDA December Crop Report Be a Market Mover/Surprise?

Historically, the USDA December crop report is a non-event or another dud report as the USDA reserves any final supply changes to the final report in January of the following year in this case 2026. But after the longest U.S. government shutdown in history at 43 days and no October crop report will they provide more data/surprise and make an exception?
Our China U.S. soybean purchase tracker is now at 26.6% or a total of 3.2 mmt but for traders it’s taking too long to unfold.
The final Stats Canada production report was bearish canola and wheat projection a record crop in both (it adds to the global glut of supplies) and bullish local corn and soybean prices in Ontario/Quebec thanks to a drought. It will not help the fund flow short-term, the USDA may need to offset it?
A U.S. Fed interest rate cut of another 25-basis point next Wednesday (probability 87.1%) could help fund flow and sentiment in stock and ag commodities into year end.
More inflows into Bitcoin this past week saw prices rebound back above 90,000 with support at 82,000 and resistance at 96,000.
A V-shaped bottom in cattle suggest the lows are in after Mexico reported another new world screwworm case. Lower weights, seasonal demand and higher U.S. beef select/choice values with a continued closure of the Mexican border to cattle will result in a resumption of higher cattle futures into yearend.
Australia is expected to produce its 3rd largest wheat crop ever at 36 mmt adding to the global glut of supplies.
Reports of ASF in hogs in Spain the largest pork exporter in Europe could see the U.S. win more pork export business long-term.
If the rains verify into next week of 3-5 inches for Brazil it would go a long way to fixing the dry regions from the last 2-months, but the European weather model has been wrong for the past 2-months!
Natural gas futures are surging to the 3rd price count as frigid hold temps set in.
CDN $ is also surging to end the week on a very resilient economy and better employment numbers suggesting no interest rate cuts next week.
Finally, the CFTC report showed funds were net buyers of soybeans but sellers of corn, canola and wheat. In real time the funds have gone back to selling as they take some profits.