For winter wheat growers chasing higher yields, Michigan State University wheat extension specialist Dennis Pennington says one management decision stands above the rest: plant on time.
In this episode of RealAgriculture’s Wheat School, Pennington joins host Bernard Tobin at the C&M Seeds Wheat Wednesday field day in Palmerston, Ont., to discuss how planting date, tiller development, and row spacing work together to build the head counts required for high-yielding wheat.
“Planting on time is probably the most important,” says Pennington. “The growers that have the highest yield potential are planting at their optimum window. They are not planting late.”
Pennington points to Michigan State research comparing five planting dates, from mid-September through mid-November. Wheat planted early enough to develop three or more tillers before winter produced yields around 160 bushels per acre.
Increasing seeding rates can help compensate for late planting, but Pennington says it can't restore all the lost yield potential. “You’re never going to get back to what your original yield potential was,” he says.
Why are those fall tillers so important? Pennington says increasing the number of productive heads per square metre is a key driver of wheat yield. Primary tillers develop their own root systems, giving them better access to water and nutrients. Later-developing secondary tillers rely on primary tillers and tend to be less productive.
Row spacing can also influence how effectively plants develop productive tillers. Pennington’s research compared a range of row widths — 5, 7.5, 10 and 15 inches. Five-inch rows yielded about 10.5 bushels per acre more than 7.5-inch rows and 13.6 bushels more than 10-inch rows. Compared with 15-inch rows, the advantage climbed to 27 bushels per acre.
Pennington says narrower rows, combined with lower seeding rates and more uniform seed spacing, give individual plants more room to develop roots and productive tillers. That can ultimately translate into more heads per square metre and greater yield potential.
For growers planning this fall’s wheat crop, the message is straightforward: prioritize timely planting first, then use row spacing and seeding rate to create the uniform, well-tillered stand needed to capture that yield potential.
Check out more wheat management tips on Wheat School.
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Read more » It's time to plant winter wheat. On this episode of The Wheat School, Michigan State Wheat Specialist Dennis Pennington stresses that planting on time is critical for high yields. He also shares how productive tillers and row spacing can fuel those high head counts that drive yield potential.
The Wheat School on RealAgriculture.com is brought to you by Bayer CropScience and CNMC.
Dennis, today you've been discussing the keys to growing high-yielding wheat. 2 things that really stood out for me, and I want to focus on those today. You say the single thing that can really improve yield potential is planting on time.
Yeah, of all the different management practises, planting on time is probably the most important. We've done small plot research, we've done on-farm research, and the data holds true in the end that we're seeing as well. is that the growers that have the highest yield potential are planting at their optimum window. They are not planting late. So that's one of the most critical things out of all the things you can do. You're going to get the most bang for your buck out of planting on time.
Now what happens when we plant on time?
So when we plant on time, so we did a study and what I took a picture, I took a photo, I dug some plants. We had a study where we looked at 5 different planting dates Every 2 weeks starting in mid-September, every 2 weeks all the way into mid-November. So I dug these plants on December 11th, and so we're heading in toward dormancy. I would not expect a lot more growth and development here going into the winter. So the question when I pose this to growers is, all right, out of these plants, which one do you want in your field in the fall going into winter? Well, of course they always point to these 2 on the left. And there's— that's critical because we're going to look in just a second what the yield of each of these plants are and how seeding rate affects it too. Because we not only did we look at each of these planting dates, at each planting date we looked at 5 seeding rates from 0.8 million seeds all the way up to 2.4 million seeds. So we were trying to identify what's the optimum seeding density at each of these planting dates as well. And so one of the important things is the amount of development in the fall. So notice in these first 2, we've got at least 3 or even more tillers on each plant. But one of the critical things, there's kind of a timeframe at which that goes away. And so when you go 2 weeks from October 1st to the middle of October, look what happens to the number of tillers. Here you've got 0 tillers. Here you've got 3, so here you're golden. This is what you want, this at a minimum. But somewhere in this time frame, you're going to go from 3 tillers down to 2, down to 1, and eventually to none. We have a lot of wheat that gets planted within this window. So I always tell growers they want to be on the front end of this curve rather than on the back end, because if you go into the fall with no tillers, you're going to lose in yield. So let's look at some of the actual yield. Down here, this first plant is this blue line. So on the blue line, as you can see, as we go across here and the yield is up there around 160, and we go from left 0.8 million seeds all the way to the right side of the chart to 2.4 million seeds per acre, the first thing to notice is the high yield. That's very good yield. But the second thing to notice is the slope of that line is not very high, which means that there wasn't much of a Seeding rate response. So even a seeding rate of 0.8 did pretty good at achieving high yield at that planting date. So let's take plant number 2 here on October 1st. This is the blue line, so it kind of crosses over the orange line. Again, similar trend, there's not a huge response to seeding rate here, and the yield potential is pretty similar up here in that 160. Now when you move on to the plant that doesn't have any tillers, and you look at the yield of this plant, this is the grey line here. And as you go across here, again, it's pretty flat and really not a big response to seeding rate, but look at the difference in the yield potential here. This is probably about 130, maybe 132, compared to yields up in the 160s. That's almost 30 bushels difference simply by going from here to here. You've lost about 30 bushels of yield potential. I don't know of any other trial or product or anything management you can do where you're going to see a 30-bushel response. Planting date is the most important thing that you can do. So you got to get planted up here because as we continue across here, this plant is the green line, so now we got yields down around 100 and still not a big response to seeding rate. And then we get to the November 15th where it's germinated but isn't even emerged. Now we're down here, we start out a little below 80. There is a bit of a response to the higher seeding rate where at 2.4 that translates to probably 95 or near 100. So there's close to a 20 bushel benefit from increasing the seeding rate. But we used to say if you're planting later, you need to increase your seeding rate to offset the yield loss that you're going to have. Well, yes, it does help to plant higher, But you're never gonna get back to what your original yield potential was.
Now Dennis, you also talked about building productive tillers, you know, how row spacing influences, you know, head density and yield potential.
Yeah, so one of the goals with this, the planting date and then the seeding rates, one of the things that you're trying to affect, one of the yield components, is the heads per metre squared. What we're finding in our YEN as well as in our research data is The more heads per square metre, the higher your yield potential is. So, how do we manage for that? How do we get that higher head numbers? Well, tillering is an important factor of that and you can see the response to planting date with the seeding rates, but the seeding rates also impact tiller development. So, when we look at the next study, before I get into some results of the next study, Let's talk a little bit about tillers and how they form and how they develop. So as you can imagine, in the fall you plant a seed, it germinates, you get one tiller, first true leaf out, second, third, the fourth one is the first tiller, okay? So that'll become this tiller right here. Then another leaf comes, you got another tiller, a second, and then a third tiller, fourth tiller, and so on. Once you get to 5 tillers out, These are considered your primary tillers or first-order tillers. The next leaf out will be a tiller that forms on tiller number 1 right here. So this is a tiller on a tiller. The difference between a primary and a secondary tiller, this tiller that forms on here does not have a root system. So how do you get water and nutrients into that tiller stem? It comes from the primary tiller. Here. So those tend to be less productive than what the first-order tillers are. So when you're thinking about managing for your head density that you're trying to achieve, trying to bump that higher, you ultimately want to produce all of these tillers and maintain them all the way through to harvest, which is hard to do if you have a crop that's managed intensively and has adequate resources available available to it, you can keep all 5 tillers and sometimes you can get into the 6th, 7th tiller of these second-order tillers or secondary tillers. That's how these high-yield growers are achieving this. And the way that they're getting these higher tiller numbers and maintaining them is they're narrowing their row spacing and they're lowering their seeding rate. And what that does is that changes the seed spacing within the furrow, within the row. So, I got 2 different diagrams here, I got poor uniformity and optimised uniformity. The poor uniformity would be something that you would typically see with like a standard conventional spill-type drill or even an air seeder where you got seed being metered out with a metering system and then dropped into the ground, nothing at the ground level to maintain a uniform spacing between them seeds. In the trial that we'll go over here in just a minute, we actually built a precision planter with the idea that not only are we going to test row spacings, but we want to look at this placement. Can we optimise that? If we can maintain equidistant between the seeds, we're going to have an impact on the way the roots develop. And we want roots that grow more laterally and explore that topsoil more fully Because that's where the majority of our nutrients and water is at for the plant. So ideally we're looking for this, and I would say the Precision Planter got us closer to that. We're not 100%, we're nothing like corn, soybeans, you know, on their monitor they can get 98, 99% seed singulation and whatnot, but we can improve it with this planter. So let's get on to the row spacing. Typically we plant a 7.5-inch row spacing on the majority of our acres, and I think that's true in Ontario as well. So we set this We set this trial up, we tested a narrower row spacing, but then we also tested 10 and 15 because we had some growers that want to invest in a new planter that they can plant wheat and soybeans with, which makes sense. Invest in one piece of technology that they can do both with. Soybean planters can only plant, the narrowest they can plant is in 10-inch row spacing or 15, so we kind of set this up to answer the question, what's going to happen to their wheat yield if they go to that type of a planter? So what we found is that with the 5-inch row spacing compared to the 7.5, we're getting about a 10.5 bushel yield increase. The 5-inch compared to the 10-inch, about a 13.6, and the 5-inch compared to the 15, 27 bushel increase. So going to a wider row spacing really is going to lower what your yield potential considerably, and narrowing to a 5-inch will increase the yield even above the 7.5. And our high-yield guys in the Yenn, they are planting on 5-inch row spacing and they are lowering their population so that they can manage this tillering, try to improve their optimised spacing, which enhances root development and leads to more productive heads per square metre, which leads to higher yield potential.