BURLEY, Idaho — Alfalfa growers might soon not have to give in to that age-old compromise of quality or yield with new reduced lignin varieties that preserve quality with more tonnage and increased harvest flexibility.
Lignin is a complex organic compound that binds cellulose fibers and hardens and strengthens the cell walls of plants, increasing as plants mature to give structural support as plants become taller. As lignin builds, forage quality and animal digestibility decline.
Reduced lignin alfalfa varieties offer improved quality by slowing down lignin buildup in maturing alfalfa, allowing producers to extend harvest to increase yield while maintaining quality, plant breeders told growers at the Idaho Hay and Forage annual convention here Feb. 28.
Alforex Seeds has developed two low-lignin varieties using conventional plant breeding that reduce lignin 7 percent to 10 percent compared with conventional varieties, said Don Miller, director of product development for Alforex.
Both varieties maintain yield and stand persistence and offer multiple pest resistance with the added benefits of lower lignin — a good package, he said.
Growers who typically harvest at 28 days for high quality have the potential to get even better quality with a 28-day harvest. But they can also get the same high quality as conventional varieties harvested at 28 days harvesting at 35 days to gain yield, he said.
The varieties offer “more tonnage without sacrificing quality (and) any time you have a better-quality feed, you have more milk, more beef,” he said.
In addition, the extra seven days to harvest provide the flexibility to delay harvest and avoid rain damage. And the reduced lignin varieties show no increase in lodging compared with conventional varieties, he said.
“They are top-of-the-line varieties, we just added one more trait,” he said.
Alforex Seeds’ two High-Gest varieties — one dormant and one semi-dormant — are the first commercially available low-lignin alfalfa varieties and are now available to growers. Varieties with additional dormancies will be developed for future release, he said.
Forage Genetics International (FGI) has also been developing a reduced lignin trait for alfalfa and has received USDA approval for its transgenic trait developed through a partnership of government, industry and private non-profit organizations. Limited commercial introduction is expected in 2016.
More than a dozen years of multi-state trials of alfalfa with FGI’s HarvXtra trait showed a 15 to 20 percent decrease in lignin and a 10 to 15 percent increase in neutral detergent fiber digestibility and relative forage quality compared with commercial check crops, said Peter Reisen, FGI director of plant breeding.
The U.S. Dairy Forage Research Center estimates a 10 percent increase in fiber digestibility would increase U.S. milk and beef production by $350 million annually and decrease manure production by 2.8 million tons per year, Reisen said.
In addition to offering higher quality, better yield and harvest flexibility, the longer harvest schedule offered by reduced lignin varieties puts less stress on plants with the potential of increasing stand life, Reisen and Miller said.