NMSU develops drought-tolerant alfalfa variety
By Kylene Scott
New Mexico has a unique climate, allowing farmers to grow premium alfalfa hay. Farmers are even more able to manipulate quality by controlling irrigation, harvesting and baling practices. New Mexico State University researchers have nearly perfected a drought-tolerant alfalfa variety to add to the arsenal, and it is set to be released commercially in 2015.
Alfalfa producers in the state often face water restrictions for irrigation and in general have limited natural precipitation. Robert Flynn, an agronomist with the NMSU ag science center in Artesia, New Mexico, along with colleague Ian Ray, have been researching and developing drought tolerance in the NuMex Bill Melton variety. The variety is named in honor of Melton, a professor who had an alfalfa-breeding program at the university in the late 1970s.
This cultivar yields well in both wet and dry soil conditions—allowing for the alfalfa to survive during drought conditions and produce a marketable product when other varieties can’t. Flynn said some varieties do well under normal irrigation practices, but once the water is withheld, they don’t do as well. This new variety doesn’t seem to have this issue.
“We are hopeful that the variety will become a favorite under normal and limited irrigation conditions,” Flynn said. “When choosing varieties for limited water situations consider those that have a lower dormancy rating than would otherwise be chosen so that persistence will increase.”
A more dormant variety will put less energy into regrowth and more into crown and root development, which increases persistence and more efficient soil moisture use, according to Flynn.
The variety was evaluated under drought stressors—using varying amounts of water and timing of waterings.
“Time between irrigations was 28 days versus every 14 days, which is a standard practice in this region with irrigation,” Flynn said. “There was also little to no rain during the entire season which allowed the drought traits to be measured under ‘ideal’ conditions.”
When compared to traditional alfalfa varieties, their variety showed promise, according to Flynn.
“The variety could yield 9 to 15 percent more forage than other varieties under drought conditions,” he said. “The line of particular interest had more leaf area than others under drought conditions which makes for better quality forage.”
And yielding more quality forage could help improve a producer’s bottom line in times of limited alfalfa supplies because of drought conditions.
Flynn and Ray tested the variety in different locations across the state—noting the differences in location and irrigation methods in each area.
Las Cruces was the primary site for testing, and only had 14 days of irrigation frequency during the research. In 2011, there was no additional rainfall during the production year. Another testing site in Artesia had a limited and full irrigation trial under sideroll sprinkler conditions later in the project, and the variety to be released was planted in the spring of 2014 at this location, Flynn said.
The variety is aimed at New Mexico producers, but could possibly have potential in other areas.
“I think it is ‘specific’ to New Mexico growers in that the varieties that were used in the research were ones commonly grown by N.M. farmers and varieties developed by the public breeding program at NMSU,” Flynn said. “The Noble Foundation in Ardmore, Oklahoma helped support the research which suggests to me that the potential goes beyond our state’s borders.”
Researchers at NMSU have been working on alfalfa varieties since 1918, and now nearly 100 years later researchers are using both breeding methods and genetic technology. This drought-tolerant variety developed by Flynn and Ray has taken 12 years to perfect.
Flynn said Ray perfectly described the methodology of the development of this drought-tolerant variety in an article with Jay Rodman. The article is located at http://newscenter.nmsu.edu/Articles/view/8204.
“The project that we have going on here involves transferring the DNA marker alleles, which we previously determined were associated with alfalfa productivity under water deficit conditions, into different types of alfalfa that farmers grow here in the state,” Ray said. “Then we evaluate the effects of those DNA markers on forage productivity.”
DNA markers will help researchers track and select for natural genetic differences for the improved drought tolerance that’s already in the alfalfa. Later, the DNA markers are transferred into alfalfa varieties using traditional crossbreeding techniques. Those varieties that the markers are transferred to are often known to be sensitive to drought stress. The resulting productivity of the offspring with the markers can be compared to the original varieties under limited irrigation to see if there was any improvement for drought tolerance.
Flynn said even with the lack of water, the sequences of genes within the plant influence yield.
“Sequencing is identifying the order of nucleotides that can be tracked within the plant as it is being improved (hopefully) that can be related to the characteristics of interest (drought tolerance, leafiness, etc.),” he said.
Searching for the drought-tolerant genes or DNA marker-assisted selection has ben used for a number of years. There is machinery available that can quickly sequence the genes, Flynn said.
The researchers hope to continue to monitor trial plots across New Mexico throughout 2014 to evaluate and compare this variety to until it becomes commercially available in 2015.
“We want to look for other characteristics that make the variety successful in our region,” Flynn said in a recent interview. “This variety holds great promise to grow and yield under limited conditions.”
Kylene Scott can be reached by phone at 620-227-1804 or by email at firstname.lastname@example.org.