Inconsistent Rice Yields

by Jarrod Hardke, Rice Extension Agronomist - September 10, 2025

Inconsistent Rice Yields

Jarrod Hardke

As known by most and being more widely discussed, we’ve got yield issues out there.  To be blunt, 75% of my yield problem calls have been DG263L.  The other 25% have been a mixture of Ozark, CLL18, and hybrid (RT 7521 FP may be the majority of the hybrid issues).  There are plenty of good yields (and some outstanding) out there in all of these mentioned and others, but that’s the breakdown of the calls I’m getting.

It will be necessary to overgeneralize a little here, but I’ll do my best to describe what I’m seeing and hearing. Certain factors definitely seem to be at play in some fields, and other fields we don’t have a definitive explanation on.

There are three main sections to this article:  twin-stem, factors that can lead to low number of grains formed, and factors that can lead to excessive blank grains.  Note that for the factors mentioned I’m not trying to cover everything possible, but focusing on factors that appear relevant this year.  Disease pressure was overall low and has appeared to have little impact so there isn’t a focus on disease factors here.

Twin-Stem

“Twin-stem” is a term I’ve used for a lot of years now to explain a condition where plants make an additional tiller that forms/starts on an upper node above the crown.  I don’t know where I got that term or if I made it up, but I digress.  I first remember seeing this in a field of CL111 over a decade ago.

We have seen twin-stem for a long time and associated it with a range of causes.  Basically, anything that causes significant grain loss or suboptimal production on a tiller might result in a twin-stem.  We’ve noted it with herbicide drift or injury, straighthead, stalk borers, etc.

This year, it’s widespread in lower yielding fields – the plant has the nutrients it needs but wasn’t successful in its first attempt to maximize yield.  So, it produces another stem high on the plant where it can make another panicle in the shortest amount of time.  Twin-stems are a symptom of the problem, not the cause.

Fig. 1.  Twin-stem from quinclorac injury that blanked heads on hybrid in 2022.

Fig. 2.  Multiple twin-stems on low-yielding DG263L field in 2025.

Factors That Can Lead to Low Number of Grains Formed

Late Nitrogen

When the first calls started coming in weeks ago, it seemed as though there were a few common denominators for fields yielding 100-150 bu/acre, which was 20-90 bu off of expectation.  Fields that didn’t receive any nitrogen (N) until close to green ring seemed to explain some loss.

In general, more complaint fields were late on N than any one reason that stood out.  Not enough time to get N into the plant prior to the formation of grains (~1/2-inch internode elongation) can noticeably reduce yields.  However, the N still gets taken up so fields have a good appearance, and they still want to try to make as much grain as possible, which leads to some different growth responses.

You might even see this as a gradient in fields, because wetter ground tends to keep rice progressing while ground that dries out can cause rice to slow down.  I think this at times explains our ability to not be as penalized by fertilizing rice late in dry years, but in wet years it bites us.

Late N application can result in a lower number of grains per panicle.  And, we will see almost all the grains end up filled on these smaller panicles – where in normal yielding rice it is typical to see 15-20% blank kernels.

Cloudy Weather

We know from basic research, and experience in 2015, that significant cloudy weather for the two weeks before and/or after reproduction begins (green ring) can negatively impact grain formation.  Fewer grains formed – similar to delayed N described above.  Earlier-planted rice was reaching green ring by early June when it had been cloudy and raining for the previous month.

Fig. 3.  Weather for May 2025 at Little Rock showing 21 of 31 days cloudy or mostly cloudy.

Factors That Can Lead to Excessive Blank Grains

Late Herbicide Applications

While late herbicide applications have seemed less of a cause this year, they do and have happened.  Most concerning have been high rates of Facet or Loyant near joint movement.  Drift of other herbicides could also be in play on some fields so we have to look out for any pattern to our low yields.

Pop-Up Storms

Rain, what rain?  Most had absolutely no rain during the flowering window but there were areas of the state that had some isolated pop-up thunderstorms at mid-day during flowering.  We know this can cause excessive blanking if it occurs at the wrong time.  But this is a minimal factor in 2025.

High Nighttime Temperatures

High nighttime temperatures were present for an extremely long stretch this summer, as was well documented.  Most often, these periods are short enough that we don’t experience effects beyond grain quality and milling issues.  That may not have been the case this year, as very high, prolonged nighttime temperatures can impact the way pollen is formed and released, and how pollen germinates.  If this is impacted, sterility (blanking) can become an issue.

Fig. 4.  Cumulative Nighttime Temperatures of 74 F or greater in Stuttgart, AR for June 1 to August 30, 2025.  Note the highest years of accumulation are 2010, 2025, 2011, and 2016.

Some have row rice fields where the flooded lower end is performing much worse than the non-flooded upper end.  Well, rice didn’t suddenly stop liking a flood, so there’s more to it.  In levee fields, as well as the lower ends of row rice fields that were flooded, during the worst of the heat, the water may have heated up adding stress to the rice.

Consider how sensitive rice can be during reproductive growth.  In rice-growing areas where cold temperatures are a concern for causing sterility, it is recommended to increase flood depth to insulate the forming panicle from low nighttime temperatures to minimize blanking (sterility).  Which leads to the opposite, heat, being able to also cause a negative impact on rice in reproductive stages.  Requiring rice to undergo excessive respiration takes energy away from grain development.

In 2016, the most recent year with high temps similar to this one (day and night), we routinely noticed in levee (flooded) fields that yield maps were inverted – that is, instead of seeing low yields near cold water inlets and getting better further away, the rice was best near the well and got worse the further away from the well.

In Fig. 5 below, the top field is a row rice field where the top of the field is on the right and the flooded bottom is on the left, showing low yields in the bottom flooded area.  The bottom field in the figure is a levee field using multiple-inlet irrigation.  Yields are worst at the bottom of the figure (furthest away from water entering each paddy) and at the far left in the furthest paddies (where water cascaded in the last few) – and the best yields are in the paddies on the right closest to the water inlet.

In hindsight, maybe we should have focused on moving water through the fields more and even dropping boards and letting water run through row rice fields more.  But of course, in the heat we were combatting it would have seemed a crazy notion while just trying to keep up with irrigation in drought conditions.

Fig. 5.  Field of row rice (top) and levee rice (bottom) showing reduced yields in areas furthest from water inlet in 2025.

Final Thoughts

The most likely root cause of issues will depend on the specific set of circumstances in each field.  There will always be fields that are nearly impossible to explain, sometimes because it’s a combination of issues, and other times because we just can’t know enough.  At this point, these are the main factors to consider when trying to determine what happened with lower-yielding fields this year.

If you have very few blank grains and the yield isn’t there – the issue points to earlier season issues during early reproductive growth.  If you have excessive blank grain – the issue points to a problem near heading or at flowering that caused that blanking.

DD50 Rice Management Program is Live

The DD50 Rice Management Program is live and ready for fields to be enrolled for the 2025 season.  All log-in and producer information has been retained from the 2024 season, so if you used the program last year you can log in just as you did last year.  Log in and enroll fields here:  https://dd50.uada.edu.

Use the Arkansas Rice Advisor Internet App!

The Arkansas Rice Advisor site https://riceadvisor.uada.edu functions like an app on your mobile device.  There you can readily access the DD50 program, rice seeding rate calculator, drill calibration, fertilizer and N rate calculators, publications, and more.

Additional Information

Arkansas Rice Updates are published periodically to provide timely information and recommendations for rice production in Arkansas.  If you would like to be added to this email list, please send your request to rice@uada.edu.

This information will also be posted to the Arkansas Row Crops blog (http://www.arkansas-crops.com/) where additional information from Extension specialists can be found.

More information on rice production, including access to all publications and reports, can be found at http://www.uaex.uada.edu/rice.

Acknowledgements

We sincerely appreciate the support for this publication provided by the rice farmers of Arkansas and administered by the Arkansas Rice Research and Promotion Board.

The authors greatly appreciate the feedback and contributions of all growers, county agents, consultants, and rice industry stakeholders.