Study at Texas A&M AgriLife center in Uvalde may help boost Texas spinach industry

Writer: Paul Schattenberg, 210-859-5752, paschattenberg@ag.tamu.edu

Contact: Dr. Vijay Joshi, 210-278-9151, vijay.joshi@ag.tamu.edu

UVALDE – Research at the Texas A&M AgriLife Research and Extension Center in Uvalde could help re-establish the Texas Winter Garden as one of the premiere areas for spinach production, including organic production, in the U.S. .   

Spinach production in the Texas Winter Garden area has grown, but overall production is still far less than during the region’s historic boom periods. (Texas A&M AgriLife Extension Service photo)

According to the Texas State Historical Association, spinach was planted primarily in the Texas Winter Garden area because of its abundant water, fertile soil, mild climate and an availability of labor. From its beginnings in 1917 to the present, the spinach industry in Texas has had boom and bust periods, with the highest production in the 1930s, ‘40s and ‘50s, followed by a decline in the ‘60s.

While the 1970s brought a resurgence in Texas’ spinach production, particularly conventional production, today there are still only about 1,100 acres dedicated to fresh-market spinach production and about the same dedicated to spinach for processing.

“But in recent years, sales of organic products have shown dramatic increases in demand domestically and for export, as consumers associate organic products with better health and safety from chemical residue,” said Dr. Vijay Joshi, Texas A&M AgriLife Research systems physiologist at the center.

Texas consumers spend more than a billion dollars per year on organic food, according to the U.S. Department of Agriculture’s National Agricultural Statistical Service. The state ranks 17th in the number of organic crops, sixth in total value of organic agricultural products sold and ninth in total organic acreage.

“According to the 2014 organic survey by USDA National Agricultural Statistics Service; spinach ranked second after lettuce in organic vegetable production, accounting for $117 million in sales nationwide,” Joshi said. “And although this needs further scientific validation, organic spinach is often considered to efficiently capitalize nutraceutical compounds such as iron, lutein, vitamins, minerals and antioxidants.”

However, Joshi said, organic spinach production falls short of the market demand, not just because of less productivity and resource-use efficiency but also from lack of availability of varieties adapted to organic farming.

More than 300 spinach cultivars from throughout the world were planted using both organic and conventional systems. (Texas A&M AgriLife Extension Service photo)

“So we are in the process of screening various spinach varieties and identifying improved nitrogen-use efficiency as a first step toward developing cultivars adapted to both conventional and organic production in Texas,” he said.

Joshi said most cultivars used for conventional spinach production have low yield stability under low-input organic farming environments, so the current challenge in both conventional and organic spinach production is to increase productivity by improving crop resistance to diseases and tolerance to environmental stresses.

“It also requires optimizing nitrogen-use efficiency to help reduce production costs and minimize environmental problems due to leaching of nitrates into the water table,” he said.

Joshi said while Dr. Carlos Avila, a research associate with AgriLife Research at the Texas A&M AgriLife Research and Extension Center at Weslaco, is leading efforts to study leaf quality traits and anthracnose resistance in the spinach cultivars being tested, his efforts are focusing on assessing nitrogen-use efficiency. Anthracnose is a fungal disease affecting spinach, which begins as small, dark olive-colored spots on the leaf, and can spread to produce large lesions that kill the entire leaf.

Sign at the organic field area of the Uvalde center. (Texas A&M AgriLife Research photo)

Joshi noted the Uvalde center has had a certified organic field for the past four years, and the field crops tested are routinely nurtured to promote biological activity by crop rotations and adding soil amendments using organically accepted products to provide sufficient nutrients for growth.

For the study, Joshi and Avila acquired a panel of more than 300 spinach samples from the USDA Germplasm Resources Information Network.

The samples used represented spinach varieties grown in the U.S., Canada, Mexico, Europe, South America, North Africa, the Middle East and elsewhere, providing   complete genus diversity. All of the 300-plus cultivars were planted in both organic and conventional fields at the Uvalde center.

“For nitrogen-use efficiency evaluation, spinach germplasm is being grown simultaneously under organic and conventional systems at the center,” he explained. “This will be used to measure leaf biomass, chlorophyll and biochemical traits associated with nitrogen-use efficiency. These include inorganic nitrate, ammonium, amino acids and mineral contents such as iron, magnesium, copper and calcium.”

Dr. Joshi next to some of the lab equipment he will use to identify markers for spinach nitrogen-use efficiency. (Texas A&M AgriLife Research photo)

Joshi said in order to accelerate cultivar development; molecular tools for marker-assisted selection will be developed. The spinach population will be sequenced to identify single nucleotide polymorphisms linked to spinach traits using genome wide selection association  approach.

“The sequencing data will be used by both Dr. Avila and myself to map traits associated with improved leaf quality, anthracnose resistance and nitrogen-use efficiency, respectively,” Joshi said.

He said superior trait performance under relatively suboptimal organic field settings and better low nitrogen-use efficiency would validate the genotypic and regional adaptability for organic farming.

“The cultivars showing higher yields under limited nitrogen availability would help in cutting the unnecessary inputs of fertilizers, as well as reduce excessive runoff and potentially unhealthy levels of free inorganic nitrates,” Joshi said.

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