Writer: Jay Rodman, 575-646-1996, firstname.lastname@example.org
What if cotton production wasn't all about the lint, the fiber we use so extensively for clothing and other products? What if the seeds, which form a significant part of the boll, could, like sunflower seeds, be used in human foods and in feed for a wide range of domesticated animals?
In such a world, cotton producers would make more money on their crop, because more of the plant would be of value; livestock producers and aquaculturalists would have another, and perhaps less expensive, feed option for their animals; and consumers would have new food products. Think cottonseed oil for salads; baking and frying; cottonseed butter for individuals with peanut allergies; cottonseed granola bars; or cotton-based ice cream.
The main impediment to realizing this scenario is the presence of high levels of gossypol in cottonseed. Gossypol is a natural toxin, found in most varieties of cotton that makes all of the plant's tissue, including the seeds, inedible by humans and most animals. It acts as a natural defense, helping to limit damage from chewing insects.
Currently, cottonseed byproducts are used in some cattle feed, since ruminants, with their special digestive system, can tolerate limited amounts of gossypol. Using gossypol-laden cottonseed oil or meal in food for humans or in feed for poultry, hogs, shrimp or catfish is out of the question.
Gossypol is produced by small glands found throughout the above-ground tissue of most cotton plants, and therefore varieties without those glands, and which therefore do not produce the toxin, are referred to as "glandless" cotton. Gossypol-producing varieties are frequently referred to as "glanded" cotton.
Several New Mexico State University researchers are involved in field and lab trials of a glandless variety of cotton, Acala-GLS. The research trials, which include agronomic and insect resistance evaluation, are funded by Cotton Incorporated, a national organization that supports the cotton industry.
Acala is one of the leading varieties of cotton, due to its combination of high fiber quality and productivity. In this research, the glandless Acala is being compared to two other Acala varieties, Acala 1517-99 and 1517-08, in terms of productivity and of susceptibility to insect pests.
The principal investigators on CI grants involving glandless cotton are John Idowu, Extension agronomist in the Department of Extension Plant Sciences; Jane Pierce, Extension entomologist in EPS and associate professor in the Department of Entomology, Plant Pathology and Weed Science, who is based at NMSU's Agricultural Science Center at Artesia; and Tracey Carrillo, assistant director of campus farm operations and superintendant of NMSU's Leyendecker Plant Science Center and Fabian Garcia Research Center.
Also participating in various aspects of the glandless cotton research are Jinfa Zhang, associate professor in the Department of Plant and Environmental Sciences, who heads up NMSU's long-standing Cotton Breeding and Research program; Scott Bundy, associate professor and entomologist in EPPWS; and Robert Flynn, associate professor and Extension agronomist in EPS and superintendant of the Artesia science center.
The field and lab experiments on glandless cotton are being conducted in and near Las Cruces and Artesia. The Las Cruces locations are the Leyendecker science center and private farms near La Union and Anthony; the Artesia locations are the Artesia science center and a private farm near Hagerman.
This idea of expanding the use of cottonseed meal and oil is not new, but actually implementing the dream has yet to prove commercially viable. With glanded cotton, the additional processing required to remove gossypol from the seed products makes the meal and oil more costly than other widely available oil and protein sources. With glandless varieties, the pest pressure, lower yield and lack of a robust market for the gossypol-free seed have deterred producers.
Varieties of gossypol-free cotton have existed for a long time - a variety of such cotton, with variable density of gossypol glands, was raised by the Hopis of Arizona more than 100 years ago. Seeds from that variety, dubbed Gossypium hopi, were actually used in U.S. Department of Agriculture upland cotton breeding projects beginning as early as 1905. However, the issue back then was not the lack of gossypol, but rather Hopi cotton's early maturation and its viability in arid environments. Introducing those characteristics into upland varieties, with their larger bolls and longer, thicker lint, was the breeding goal.
According to Zhang, it wasn't until the late 1950s that there was discussion of developing glandless cotton for food and feed applications. He said that glandless cotton was raised extensively in both Africa and China in the 1990s with the idea of using the seed products more widely for food and feed, but the economic forces at work did not support the enterprise.
The Acala-GLS in the NMSU study was originally developed and tested in California, where it faced higher pest pressure and produced lower yield than other Acala varieties. NMSU researchers hope that New Mexico will prove more hospitable for growing glandless cotton than many other locations, since the two most serious cotton pests, pink bollworm and boll weevil, have been largely eradicated and pest pressure from other insects is relatively low.
"Right now, here in New Mexico, there have been major eradication initiatives of the major cotton pests, like pink bollworm and boll weevil, and the lygus pressure is very low, so we are thinking that this cotton might be able to do well," said Idowu in a recent interview at his Leyendecker test plot.
"This is the second year of our study. Last year we tested it, and we saw that we were able to get reasonable, significant lint yield and seed yield from the glandless cotton. So far it's looking good, we have not had any major pest attack on the crops. The cotton at this stage is looking better than even last year so we are expecting a higher yield this year."
According to Idowu, what was unclear after the first year was whether the somewhat lower yield in both lint and seed from the Acala-GLS, compared to the other Acala varieties, was due to differences in pest pressure or other factors, perhaps genetic productivity differences among the three varieties. The next step was to monitor the insects and try to assess their impact on the glandless cotton.
At the Artesia science center, Pierce and graduate student Drew Garnett have been monitoring insects in their cotton research plots, as well as studying insect responses to glandless cotton under more controlled laboratory conditions. They are primarily comparing damage to glandless and glanded cotton from beet armyworms, bollworm larvae, thrips and lygus bugs.
At one point, Pierce found that thrip counts in an Artesia field trial were significantly higher in the glanded cotton plots than in the glandless cotton plots.
"This was unexpected, but who knows?" she said, emphasizing that this was only one test. "Maybe gossypol avoidance isn't a priority for thrips."
"Beet armyworm, on the other hand, does produce more damage in glandless cotton, as was evident in 2010 field trials," Pierce continued. "Field to laboratory trials being conducted this year indicate beet armyworm larvae grow larger feeding on glandless compared to conventional glanded cotton. Bollworm larvae also grew more when fed glandless cotton."
Pierce said that both beet armyworm and bollworm larvae showed some preference in the lab for glandless rather than glanded cotton, but notes that in the field, larvae have limited ability to move.
"There was no evidence that female moths of these species preferred to lay their eggs on glandless cotton plants, which would be more of a concern to growers," she said.
Idowu said that the current research is slated to be continued for a third year, and that yield from year two will not be determined for several more months. All of the field and lab results are very tentative, but he is very encouraged by what he has seen so far.
What would it take to make glandless cotton viable for New Mexico farmers? High yield of high quality lint and seed in the harsh New Mexico environment with minimal input of water, fertilizer, pesticides and herbicides - and a robust market for edible cottonseed products.
Zhang has glandless Acala plants interspersed with commercial varieties in plots unrelated to the studies funded by Cotton Incorporated. He is in the early stages of developing what he hopes will be a more productive variety of glandless cotton. As with all of his breeding projects, patience is essential; the process of replicated field tests that lead to official recognition of a new variety can take several years.
Carrillo, in his leadership capacity with NMSU's Cotton Task Force, has been working with faculty and staff in several disciplines whose efforts might lead to enhanced commercial viability for glandless cotton. This includes not only the agricultural researchers but also people involved in product development and testing. For instance, Colleen Caldwell, an adjunct associate professor in NMSU's Department of Fish, Wildlife and Conservation Ecology and the New Mexico unit leader for the U.S. Geological Survey's Biological Resources Division, is raising Pacific shrimp in a closed tank system using a glandless cottonseed meal feed. And Nancy Flores, Extension food technology specialist, is beginning work on incorporating cottonseed oil and meal into new food products.
Glandless cotton is likely to play a part in NMSU's sustainability efforts. Carrillo has proposed that campus food services use oil from NMSU glandless cotton plants in their food preparation, after which he would run the used oil through a newly acquired biodiesel machine. The resulting fuel would be used to power NMSU farm vehicles.
"EYE ON RESEARCH" is provided by New Mexico State University. This week's feature was written by Jay A. Rodman of University Communications.
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