Sorghum 3

(Jim) Good morning folks, welcome to That’s My Farm. I’m Jim Shroyer your host. And we’re in luck because we’re on the Agronomy Farm here at the K-State Campus. And we’re also going to be talking to several researchers. One in particular, sorghum response after cover crops which is important to a lot of people. And also scientists are using apparatuses like the heat tent and the rain out shelter which is behind me. So, get your cup of coffee and come on back. We’ll start the show.

Closed Captioning Brought to you by the Kansas Soybean Commission. The Soybean Checkoff, Progress Powered by Kansas Farmers.

(Jim) Good morning folks, welcome to That’s My Farm. I’m Jim Shroyer your host. And we’re in luck because we’re still talking sorghum at the Agronomy Farm here on the K-State Campus. And with us we have a good friend of us, Dr. Doug Jardine. Doug is our Extension Plant Pathologist. And Doug, since we’re talking sorghum, we’ve got sorghum as a back drop here. We had some issues this year with lodging and some other issues with sorghum this year, besides sugarcane aphid that came in. So, kinda give us a recap on some of the issues. (Doug) This year the diseases changed according to the weather. And this year it seems like the weather was just perfect for fusarium stalk rot. It’s a disease we deal with every year, but some years it’s worse than others. This year it’s a little worse than average, especially if you’re farming up in north central or northwest Kansas. On a recent tour I was able to drive around and there were a number of fields where large patches of the field were laying flat on the ground. And on closer examination it was fusarium stalk rot. And again it’s related to weather. That particular disease likes it wet early, dry late. (Jim) What about charcoal rot? (Doug) Well you know charcoal rot can be found in some fields, especially in some places in the state that maybe missed some rains because we know charcoal rot likes the hotter, dryer weather. And of course, it’s not uncommon to find both of the stalk rots even in the same field. So, yes there definitely was some out there. (Jim) So when I think of charcoal rot, I think of soybeans. And I think of southeast Kansas. But it’s not necessarily confined to the good conditions that it likes down in southeast, it can be anywhere as you say. (Doug) Right, you know charcoal rot can go to not only soybeans and grain sorghum, but also corn and sunflowers. It has over 250 different hosts. And any place where it gets very hot and very dry in July and August, regardless of the crop, those are the conditions favorable for charcoal rot. (Jim) OK, I noticed before we were talking here on the air, you were pointing out some sooty mold. So, what’s that problem? (Doug) Well the disease is called sooty stripe and it’s the most common foliar disease in Kansas. Many of our hybrids are actually quite resistant to it, but unfortunately, some of those that are most favored by the growers are highly susceptible. There’s probably a little bit of yield drag involved when they put the resistance into those hybrids. Sooty stripe is favored by frequent rain and we had that in a lot of places in the state because the spores for this fungus are what we call splash dispersed. So when the rain impacts on the soil or the old crop residue, it’s going to splash the spores up in the air, they’re gonna land on the sorghum plant, infect the lower leaves and then progressively they’ll move up the plant. And we did some research about 20 years ago here in Kansas that showed on a really susceptible variety, you could get up to about a 35 percent yield loss. Unfortunately, there are no fungicides registered for its use so really we have to deal with it through hybrid selection and to some point rotation and maybe tillage. (Jim) Doug, appreciate you taking time to talk to us about sorghum disease and potential problems. And folks, stay with us, we’ll be right back after these words from our sponsors.

(Jim) Welcome back to That’s My Farm. I’m Jim Shroyer your host and with us we have Dr. Kraig Roozeboom, our Cropping Systems Researcher. And I see one of the things you’re researching these days Kraig is cover crops and its effect on sorghum. So, I guess I’ll let you take it away on cover crops effect on sorghum. (Kraig) OK, well we look at cover crops in sorghum cropping systems and we’ve been growing various types of cover crops ahead of sorghum and after wheat planting. And so if you just look at broad categories you’ve got summer and winter cover crops and you’ve got legume and non-legume cover crops. And so, we’ve got representations from each of those classes in there. If you look at sorghum response in those systems, if you grow sorghum after the summer legumes we can grow that sorghum, get similar yields from that sorghum in these central and eastern Kansas type environments where we’re not severely water limited. Similar yields with anywhere from 40 to 60 pounds less nitrogen than if we were just in a fallow situation following the wheat harvest. We’ve also looked at summer grasses. Sorghum sedan grass, say. In that case, that’s a high biomass producer, high seed in ratio, tends to tie up nitrogen. (Jim) Carbon to nitrogen ratio seed to in. (Kraig) Right. And so it doesn’t cycle as quickly, ties up nitrogen and it takes us another 40 to 80 pounds additional in to get similar yields. And so you need to think about what your objectives are, what your cropping sequence is. If you’re in a situation where you need a lot of persistent residue, well then look at these summer annual grasses, or winter annual small grains. High seed in ratio types of things. If you want to cycle nutrients more quickly, look at things like brassicas, radishes, grape seed, those kind of things. If you really want to add nitrogen, summer legumes like sun hemp, soybeans, forage soybeans, they’ve had the biggest impact in our sorghum systems. (Jim) OK, now let’s talk a little bit more about the actual nuts and bolts here. So, you’re talking about after wheat, planting that would be a fall or a winter cover crop, right? And then killing it in the springtime prior to sorghum planting, right? (Kraig) That’s right. For the winter type cover crops, you can also plant those summer cover crops immediately after wheat harvest. (Jim) Right OK. (Kraig) And then they will terminate in the September/Fall time frame. (Jim) OK. No till planting into it? (Kraig) All no till systems that we’re looking at primarily. (Jim) Right. (Kraig) And that’s one of the tenants of no till is that in no till systems diversity is a good thing because you don’t have that tillage getting rid of residue. (Jim) Right. (Kraig) And taking care of things. (Jim) Keeping the ground covered. (Kraig) And so you keep the ground covered. You introduce diversity into that system. And cover crops are just a way to further intensify and further diversify these no till systems. (Jim) We’ve gotta take a break here. So, stay with us. Don’t run off. A lot of my guests do. They run off during the break. So folks, stay with us, we’ll be right back after these words from our sponsors.

(Jim) Welcome back to That’s My Farm. I’m Jim Shroyer and with us we have Dr. Kraig Roozeboom. And we are talking about sorghum’s response to cover crops, various cover crops. You were talking about the high seed to in ratio like some of the grasses that you probably have to add nitrogen to the sorghum as opposed to the legumes type of cover crops that you can probably, you don’t have to put on as much. But what are we standing in right here? What we see is a forage sorghum or sorghum sedan grass here, but there’s more in here than just that. (Kraig) That’s right. This happens to be a mixture of three components, including the sorghum sedan which is the dominant visual component. Also have tillage radish in here. (Jim) I see those down there. (Kraig) And so that’s more of a fall, cool season brassica. And the idea being here as this was planted during the summer, the sorghum sedan comes up rapidly, we get a lot of good growth during the hot part of the summer. The cool season brassica comes on then at the same time, but now it really comes into its own in the fall and maybe picks up, kinda grabs the baton as you might say from the sorghum sedan. We also have in here some crimson clover, which is really hard to find, but you can find some. Theoretically as frost comes we kill off the sorghum sedan, frost will kill the radishes. Potentially the clover will survive through the winter and may take off and give us substantial growth in the spring. (Jim) And nitrogen obviously. (Kraig) Potentially some nitrogen fixation. Honestly as we look at single components, it’s really tough to get a lot of nitrogen out of these winter legumes just because of the lack of growth we’ve had and the inconsistency with winter survival. (Jim) Right, right. (Kraig) Legumes have a harder time surviving. But if they do survive, we can get a 50, 30 to 50 pound equivalent of nitrogen contribution. The brassicas do a very nice job of scavenging that nitrogen. (Jim) Recycling from down deep. (Kraig) Bring it from down deep. Make it available that next season. It’s not like you get a big flush like a fertilizer application, it’s more a situation where you’re raising the background level of mineralized nitrogen. (Jim) OK. Let’s talk about water use. (Kraig) Right, so that’s a big concern in much of our Kansas cropping systems. Water’s the main limiting factor. When you grow something like this, it takes water to grow this. What’s the implication for my cash crop, right? (Jim) Yea, the next crop, yea. (Kraig) Exactly. The crop that’s following this. We don’t want to set ourselves up for failure. And so we’ve been looking at it here more in the eastern third to two thirds of the state. Over time there’s an indication that in most cases if we’re careful about managing it, water doesn’t become the limiting factor. Our systems recharge sufficiently. And especially if you’ve got good residue in place from the cover crop. And there’s evidence that these crops actually can increase filtration by two to maybe three times as much as fallow situation. That we can recharge and do a pretty nice job. (Jim) Kraig, thanks for taking time for talking to us about sorghum’s response to the various cover crops. (Kraig) OK. Enjoyed it. Thank you. (Jim) Folks, stay with us, we’ll be right back after these words from our sponsors.

(Jim) Welcome back to That’s My Farm. I’m Jim Shroyer and with us we have our Crop Physiologist, Krishna Jagadish and I’ll call you Dr. K, OK? (Krishna) Yep, that’s fine. (Jim) Krishna thanks for being with us. And we’re at the Sorghum Field Day of course. Why sorghum and why is it so important in Kansas? And what needs to be done? (Krishna) Well sorghum has been in Kansas for a very long while, let’s say about 100 years or more. (Jim) More, yea. (Krishna) But what has happened is now the climate change, there is a change in the climate, and the environment that is happening. So, there’s a lot of potential for improving sorghum. So, we have been growing sorghum, but we have so much more potential in sorghum that it can be improved. And that’s what we are trying to do. And basically trying to address if there are stresses that actually limit crop production or sorghum production. And that’s what we are trying to reduce over here. (Jim) And behind us, we have an excellent example. This is a heat tent behind us. And you’ve got a lot of different types of sorghums in here. So, kind of tell us a little bit about that and why we’re using the heat tent? (Krishna) These are specialized heat tents. And this allows you to study different kinds of sorghum. (Jim) From around the world basically. (Krishna) From around the world. And these lines that you see behind you, they are coming from Africa, they are coming from Asia. And they have different traits of adaptation. Which some of the sorghum lines that we have here in Kansas, may not have it. So, that’s what we are trying to do here. (Jim) OK. (Krishna) So basically, in sorghum during the grain filling stage, that’s when you have most of this drought stress and the heat stress coming in. And it’s becoming more frequent and more intense. So, we are trying to make sorghum, Kansas sorghum in a way that is more productive, even if it is in more hotter environments. So what the heat tent does here is it actually rises the temperature by about eight to ten degrees Centigrade inside the tents. (Jim) Oh my goodness. (Krishna) You can’t rise it to that level, there is a thermostat that you can rise it by any time between plus five to plus ten degrees depending upon the crop and depending upon the stage. (Jim) Right. (Krishna) These heat tents are actually placed upon the crop very specifically at very particular stage, when you know that sorghum is really sensitive. (Jim) Right, right. (Krishna) And these are placed on top of that and you take a number of physiological measurements, such as photosynthesis, or you can take chlorophyll flourishments. We also try to tie into the yield as well as the grain filling process. (Jim) Correlate it. (Krishna) Exactly. And then that’s what is interesting to the breeder and what they can follow it from there that they leave behind. And we test all of these, and when you have these lines which are really productive or superior already have in Kansas, then we try to chase that line. (Jim) Right. (Krishna) What is in that line that is making it so much more tolerant than what we already have in Kansas? (Jim) Like a stay green trait or I see we have a chlorophyll meter still on the plant here. Those are some of the traits like you mentioned that will help identify why that particular line or variety or whatever it is, that we can bring it in to ours. Is that a fair assessment? (Krishna) Pretty much. Along the same lines. So what happens is as I said the chlorophyll actually produces sugars and then it is stored in the stem. So, what happens during the grain filling stage, is the sugars that are there are very important for the grain filling. (Jim) Right. (Krishna) So, we study what happens to the sugar and whether it is really translocated well into the grain, which is sometimes a major bottleneck in some of the sorghum culled to us. (Jim) Let’s hold that thought. My camera man is telling me it’s time for a break. So, don’t run away. You folks at home, don’t run away either. We’ll be right back after these words from our sponsors.

(Jim) Welcome back to That’s My Farm and with us we have Krishna Jagadish. And I’ll say Dr. K again. So Krishna, thanks for being with us and not running off during the break there. We talked a little bit about the traits on heat stress over with heat tents, but this is about a little bit different critter here. Tell us what we have here and how you use it. (Krishna) Right, so, compared to the heat stress what we are trying to do here is for the drought stress, so limited amount of water is what we deal with over here. Generally during the sorghum when it is maturing, when it is actually grain filling, under Kansas conditions, generally it comes across as drought stress conditions. (Jim) Right. (Krishna) So, what we have here are called rain out shelters. (Jim) Rain out shelters. (Krishna) Rain out shelters. (Jim) They’re on tracks. (Krishna) Exactly and what this allows us to do is to keep away the natural occurrence of rainfall when we are actually trying to improve sorghum to drought stress. (Jim) Right. A rain can really mess up a study… (Krishna) Exactly. (Jim) …a drought study. (Krishna) So, you are studying drought stress, but you don’t want rain to actually interfere in your analysis. But then if you have rainfall then you lose the entire crop because you cannot actually follow up with the measurements. (Jim) Exactly, exactly. (Krishna) So, the crop under stress starts to recover and there’s no more stress for you to actually study. (Jim) For the research. So basically the study, it has to be delayed a year. (Krishna) Yea. (Jim) OK, so how does it work? It’s on a track, so how does it know, how does the shed know to cover the crop? (Krishna) At the back there is sort of a tipping bucket, which is a few milliliters of water that it needs to fill before that bucket actually tips over. (Jim) And that turns it on. (Krishna) That’s a trigger, it’s a trigger. Which basically then sets the whole thing into motion. So, this comes over here and covers the entire crop. And it stays there like that for about 35 minutes. And in the 35 minutes, if you have another tipping of the bucket then it just stays there. That means it’s still raining and it shouldn’t go back. But once it has tipped and for 35 minutes from then on it doesn’t rain or the bucket doesn’t tip, then it knows a signal then it goes back into its parking lot. You don’t have any rainfall on your plot, you can continue your research and you don’t lose your yield. (Jim) Right. That’s really interesting. So, drought stress during flowering and then grain filling, what measurements are you taking in that time frame? (Krishna) Generally during the flowering, when there is stress, then it reduces the seed numbers, so you just actually count the number of seeds that are in each of the head sorghums. And you will know that during the flowering stage that drought has affected the seed set. But then the grain filling process is a long process, it happens over time. So, what we generally do is we take photosynthesis measurements from the leaves to see whether it is actually photosynthesizing and getting the sugars that is needed for grain filling. But then we collect the grain samples every time point, about three to four days, and once every four days once. And then what you do is you over dry them and you measure them to follow up the weight that is happening. So, then you actually compare that to a control condition which is not exposed to drought stress. And then you can see the difference in the grain filling that is happening. So then looking at very diverse lines, you will start to see that the gap is much smaller in some of the lines and that’s what you want. (Jim) Right, I see that. (Krishna) And then you take such a line and you start to work with the breeders. Try to improve that trait, so that the sorghum lines produce as better, very good even under drought stress conditions. (Jim) Krishna, thanks for taking time to talk to us a little about the heat tent and the rain out shelter and how they’re used. Appreciate it. (Krishna) My pleasure Jim. (Jim) Folks, thanks for being with us on this issue of That’s My Farm. And don’t forget, next Friday about this same time, we’ll have another show of That’s My Farm. See you then.

Closed Captioning Brought to you by the Kansas Soybean Commission. The Soybean Checkoff, Progress Powered by Kansas Farmers.

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