Better sorghum seed = Better harvest results
By Kylene Scott
Fall harvest. The very words conjure up thoughts of cooler weather, massive combines, and fickle weather conditions. But in order to have that harvest, it has to start with a seed. For grain sorghum and forage sorghums, west Texas is a hotbed of seed production. Various companies and organizations are working to improve sorghum germplasm, and breeders will eventually turn the traits into productive hybrids.
Researchers like those at the Agricultural Research Service in Lubbock, Texas, provide germplasm material to both private and public breeders; however, it’s not before extensive testing that it leaves and is eventually used by breeders.
“They go through the ringer on testing everything,” Justin Weinheimer, crop improvement program director with the Sorghum Checkoff, said. “They don’t just show up and say, yeah, we’ll take your word for it. So there is many years of testing that they do in many locations across the U.S.”
Once the traits and germplasm make their way into a hybrid, they are put through extensive testing by breeders—in different environments, with different chemical regimes, etc.
“It’s just too early to tell on some of these things, but certainly the companies are valuing from literally going through their stuff with a shopping cart and seeing these things and how they work in their program,” Weinheimer said.
There are characteristics of sorghum plants that help them survive the life cycle to harvest. Seeds must first germinate and the plants must survive colder weather during early stages of their life following planting. Then standability is important to keep the plant upright, growing and make it to harvest. If strong winds happen to come at or near harvest, the grower wants to avoid lodging. Most importantly there’s yield. Researchers have come up with some unusual ways to improve yield. Drought tolerance, especially in west Texas and many parts of the High Plains, is very important as well.
Larry Richardson of Richardson Seed in Vega, Texas, said those important aspects each have their place in sorghum breeding.
“What we’re really looking for is diversity. We want to get as far away from what we have germplasm sources today that we’re using as we can,” Richardson said. “Because the bigger diversity you get, the more heterosis you get. The more heterosis you get in hybrids, the better the hybrid is going to perform—in yield, drought tolerance, stand ability, disease, everything.”
Richardson said his germplasm sources were getting too close and diversity was needed in his program once again.
“We want something that is totally off the realm, way off the spectrum,” he said. “We just want diversity as much as we can.”
Pioneer researchers in Plainview, Texas, also exchange sorghum germplasm and find it a healthy thing to do.
“For disease resistance, for providing ability to yield, I think it really gives us an advantage for a lot of our competitors that just have regional programs,” Cleve Franks, Pioneer sorghum breeder, said. “My main traits are drought tolerance and lodging resistance; mainly that’s what I breed for.”
For Pioneer sorghum, Cleve’s territory includes the Panhandle of Texas, the Oklahoma Panhandle, western Kansas, eastern Colorado, southwestern Nebraska and eastern New Mexico.
At ARS, they began to work with Chinese germplasm to develop cold tolerance traits. Burke said they started with 150 lines and worked them down to 25. From there they went to the field, where four made the cut.
“To make the cut they had to germinate about 80 percent or better at 12 degrees Celsius or about 50 to 55 degrees Fahrenheit so it had to be cold, and these things had to germinate well and have good early season vigor,” Burke said.
Those four lines have been released to the public, and the ARS team is working on new recombinant populations. These are populations that are used to identify genes and markers for cold tolerance.
“So we’ve developed these things. It takes a long time,” Burke said. “It takes seven generations to get these things developed, so we do two a year, so we have this one gone, these two will go out the door in the next six months.”
A new one is in the field now and will go out next year.
Later some Ethiopian lines were evaluated, especially since the area of the world the came from they may already have some cold tolerance. A germination test was done on the Ethiopian collection and was replicated three times. The best 125 were taken to the field, and 25 ended up looking very promising.
Lubbock weather helped test the lines pretty thoroughly, Burke said. Plantings took place April 1 and evaluations were done on April 30. A snowstorm and three days under 32 degrees tested the limits of some plants. Plants that were tall enough got nipped by the freeze, but 20 days later, they were looking good again.
“So, we have some very good cold tolerance, and you can see pretty healthy looking plants,” Burke said. “They’re not spindly. They’re pretty solid. That’s one of the nice things with the Ethiopian lines that we like.”
Standability is No. 1 for Richardson Seed, and something that is focused on before the lines go out of their research.
“If it doesn’t stand it doesn’t go. Period,” Richardson said.
Researchers at the Agricultural Research Service center in Lubbock, Texas, have been working to improve standability in sorghum as well and have been working with specific lines of sorghum material, some with much larger heads. Even with essentially double the weight above, lodging hasn’t been a problem.
“We don’t ever see lodging, and that’s one of the first things you worry about was this sort of thing,” John Burke, research leader for plant stress and germplasm development at ARS, said. “But this plant doesn’t do it, and so that’s not been an issue.”
Burke has it in fields in Lubbock, and the plants have faced 70 mph winds, and stayed upright.
ARS researcher Zhanguo Xin also has a mutant called stiff stalk, and it can be grabbed with two hands and tried to be pull it over and it won’t budge. The line has been tested in Kansas and Nebraska and has stood strong. A researcher in Kansas used a pentameter on it, and it took twice the energy to probe through the stem. Xin believes it’s not the stem doing all the work, but the roots as well.
At ARS, researchers have worked since 2000 improving sorghum and providing germplasm for public and private sorghum breeders. Xin has created a population of 6,000 mutants that are pure for specific traits.
There is one particular trait that Burke and his teams are excited about. At the tip of every normal sorghum panicle, there are three flowers, the sessile spikelet and pestles. On a standard sorghum hybrid, there is a seed and these two former flowers off to the backside of the main one. In Xin’s mutant, it sets all three flowers.
“That’s why we got really excited when he found it because we were looking for larger heads,” Burke said. “We know yield is the only thing of true importance, but we’ve started screening and looking for big heads. Turns out he found big headed ones, wasn’t just because they were big heads it was because of this characteristic.”
Comparing the mutant head to a normal head, there’s a significant difference in the total estimated weight.
“We’re getting a significant yield increase,” Burke said. “In the green house we can get essentially a doubling of yield and almost a tripling of seed number.”
Burke is excited about the new high yielding, multi-seeded lines.
“They’re in the hands of five different companies right now and we’ll see what they can do with them. We’ve never seen them in hybrid combination yet, and so we’re excited about it,” Burke said. “There’s a lot of skepticism until that happens.”
Weinheimer is also excited about the finding. He sees the advance in the mutant trait as well as other work with cold and drought tolerant traits as a margins gain.
“Even if we came out on the back end of this, and only had a 10 percent yield increase, that’s 10 percent more than any of the other companies have been able to generate through traditional breeding,” Weinheimer said. “So even a small gain relative to what you see out there, has a huge potential downstream that these companies are able to generate.”
Focuses on of research at the ARS station is water and temperature stresses. They have found a couple of drought tolerance traits in some lines, and have worked to get germplasm with the traits to breeders.
“We have new sources of stay green. We know stay green lines, post flowering drought tolerance lines tend to be pre flowering drought sensitive,” Burke said. “Pre-flowering drought tolerant lines tend to be post flowering. The two extremes.”
What the finding really has to do with is how much durin and other things are built into the plant. So if there’s very little durin and the plant is a pre-flowering drought tolerant line, it senses the soil drying sooner. The stay green doesn’t even sense the soils drying out until it’s too late. Sometimes the post flowering lines can’t sense it fast enough.
“So with this knowledge we can now go in and say, lets find the new lines that are in the middle. They have some good pre and some good post, so we can cover the environment,” Burke said. “If you know you’re going to have a late season drought, stay green’s are wonderful for them, but we need that flexibility. But I think now we understand why and which lines to look for that.”
Richardson Seed focuses mainly on grain sorghum lines that are earlier maturing but still have drought tolerance and high yields.
“We’ve got to be able to produce earlier grain sorghums with less water but still be able to get the medium and high yields,” Richardson said. “We think we’re pretty close to getting some of those. We have some on the market.”
Kylene Scott can be reached by phone at 620-227-1804 or by email at email@example.com.