“Blending” is the process of mixing the seed of two cultivars prior to planting. Depending on the cultivars and ratios used, Sterling Brooks Blanche, LSU AgCenter assistant professor and rice breeder, is seeing differences between blended seed and pure line research.
Blending seed “isn’t a new concept, but the research aspect of it is,” said Blanche at the recent Rice Research Station field day in Crowley, La. “We’re looking at new ways to analyze cultivar blends to get fair evaluation of their potential.
“As you can imagine, putting multiple varieties in the same field can be challenging, but we think there may be something going on. At this point we’re trying to learn how these varieties are interacting with each other, either positive or negative.”
Researchers “have noted some differences in height and maturity, based on whether the cultivar was in a blend or planted alone. As expected, the ratio at which it was blended determined the degree of differences.”
The first thing Blanche checked was stability — basically, a yield consistency study.
“I wanted to know if blending hybrids or varieties can increase yield consistency compared to a pure line. In our breeding program, we’re looking to develop material that has a broad adaptation. Basically, we’re looking for lines that don’t respond to changes in the environment — ideally, if a line has a 50-barrel yield potential, it’ll yield that wherever or whenever it’s planted. Of course, there will never be a perfectly stable variety, but that’s what we’re aiming for.
“So I used a similar approach to evaluate the blends to determine if they yield more consistently when exposed to a wide range of environmental conditions.”
The stability study has been in place for the last two years in statewide commercial advanced trials. It has shown the blends are about twice as stable as a hybrid. And they’re about four or five times more stable than the variety.
“This study was conducted across multiple locations, different planting dates, different soils types, herbicide programs, rainfall, etc. So there’s a blend benefit with stability. But that’s not the whole story because even though they’re stable, they can be stable with a consistently low yield.”
How were the yields? “Well, we didn’t want to look at raw yields because there were differences in seed cost. So, we analyzed them as ‘return above seed cost,’ which takes into account both yield and planting costs.”
Using those criteria, Blanche found the blends were always superior to the varieties. In some cases, “they were intermediate between the variety and hybrids. In other cases, they were equal to the hybrids.
“So, it was kind of a mixed bag. We’re certainly seeing differences in what is in the blend and at what ratio, but there is good potential with blends and the research will continue. Since blends are more stable and the yields are competitive, that translates to less risk.”
Blanche is cooperating with Bill Williams at the Northeast Research Station in St. Joseph, La., on another study on Newpath tolerance.
“This study looked at 1X, 2X and 4X rates of Newpath. They were applied to a Clearfield hybrid, a Clearfield variety (CL151) and a blend of the two at various ratios.”
How did they rank across the different Newpath rates?
“The answer probably won’t surprise you. The CL151 didn’t respond to the Newpath rates. In fact, the 4X rate had a higher yield than the 1X, probably due to additional weed control.”
Researchers saw the same in the blends. The 4X did a bit better than the 1X rate. So, the higher rates of Newpath don’t reduce yield.
“We did see some reductions in the hybrid — an 8-barrel yield reduction going from a 1X to a 2X rate.”
Another advantage of the system is in reducing lodging potential. “Lodging isn’t always a factor in our rice, but when it is, it can cause significant yield and quality reductions as well as harvest complications.
“We had a trial last year that included several hybrid variety blends. One hybrid lodged 8 percent and the other lodged 16 percent (averaged over several locations).”
Blending either of those at a 50/50 ratio with Cocodrie reduced lodging to below 2 percent.
“It virtually eliminated lodging. That isn’t surprising — that’s the classic reason why seed blending has been tried in the past.”
Blanche warns the current research is still in early stages, “and we’re not making any recommendations. But this is how we’re going about studying it.”
Picture a 100-acre field divided in two, says Blanche. The grower has enough Cocodrie seed to plant 50 acres and enough Cheniere seed to plant the other 50 acres.
“We can plant them separately, and we do all the time. Say the Cheniere cuts 40 barrels and Cocodrie cuts 30 barrels for a 35-barrel average for the 100 acres.”
However, a 50/50 blend of those two varieties shows “I’m gaining about 2 or 3 percent just by planting blended seed on the entire 100 acres. We’re seeing that both in yield and milling. So there are potential benefits although we’re still hashing out (among other things) which varieties blend better and how much of each to add to the blend. Certain combinations seem to perform better at different ratios than others.”