Finding new varieties of guar can improve wheat production

In a season suffering from drought and high fertilizer prices, Texas A&M AgriLife scientists appreciate what guar gives in crop rotation.

Guar plants that grow near Vernon. (Photo by Texas A&M AgriLife by Waltram Ravelombol)

“Guar is a drought-resistant crop with a low content that does not require expensive fertilizers,” said Waltram Ravelombol, Ph.D., a breeder of organic and special crops in Texas A&M AgriLife study and Extension Center -Vernon and Department of Soil Science and Plant Breeding. “We know that guar improves soil health and increases the yield of subsequent wheat, making it a good crop in the north for growers in the Southern Great Plains.”

Ravelombola is working on the final year of a project funded by Fr. U.S. Department of Agriculture National Institute of Nutrition and Agriculture a grant entitled “Improving Ecosystem Services through the Integration of Guar into the Southern Great Plains Wheat Growing System”. The project began in 2018 and will end this year.

Guar is a legume that means its roots can bind to Rhizobium bacteria in the soil to convert atmospheric nitrogen into fertilizer for plants and soil. It is adapted to the semi-arid conditions of Texas and is one of the most drought-resistant crops with relatively low water use.

However, new research is needed to improve the production and nitrogen-fixing properties of the crop. Ravelombola said that the varieties of guar that the project is working on were released 35 years ago and more.

“We want to give farmers more opportunities to diversify their cultivation systems,” he said. “For example, at such high fertilizer prices as now, if we had a variety that formed tubers better, it could capture more atmospheric nitrogen and leave residual nitrogen for the next crop, thus reducing the need for synthetic fertilizers for next season ».

Long-term and short-term research objectives

The long-term goal of the study is to increase and stabilize guar production in the United States and increase the sustainability of wheat cultivation systems in the Southern Great Plains region.

The immediate goal is to quantify the development of wheat and guar yields, yields, nitrogen and tuber uptake, and precipitation efficiency. In addition, Ravelombol studies the dynamics of the soil nitrogen cycle and the efficiency of nitrogen use, storage of organic carbon in the soil and biological activity of the soil.

AgriLife Research grows about 400 species of guar on approximately 8 hectares of small plots. The two research sites are in Chilicot on 4 acres and in Lockett on 2 acres. His project also includes a 1-acre farm study with New Deal Grain Co. Another 1-acre plot is located near Labak, grown in collaboration with PhD Calvin Trostle. Texas A&M AgriLife Extension ServiceLubat agronomist.

“Guar is a heat-resistant and drought-resistant crop,” Trostle said. “To the extent that climate change makes our climate warmer and drier and can affect the harvest in Texas, guar will work relatively better compared to other crops we grow.”

Guar, which has matured and dried, cuts a smaller combine blue plot
A small plot of Texas A&M AgriLife Research collects guar. (Photo by Texas A&M AgriLife by Waltram Ravelombol)

He said that in old literature reports the yield of cotton in arid areas increases to 15% after guar compared to the cotton crop, but more research is needed to evaluate this conclusion with modern varieties.

“Again, guar is a legume, and at any time we can get legumes that grow well in dry climates – and form nodules to fix nitrogen – it’s potentially a great benefit to farmers and a stable crop system,” Trostl said.

Guar is planted from mid-May to July and harvested after the first frost, which is used for delicatessen plants, usually in October or early November. Guar can be harvested with the help of combine harvesters, which are already available from most grain producers.

In the final year of the grant-funded project, Ravelombol said he would work to improve guar phenotyping using technologies such as drones, UAVs and 3D crop simulations. It will also investigate the genetic basis of nitrogen fixation in guar.

Maximum nitrogen fixation of guar crop

Nitrogen fixation is the ability of a crop in collaboration with soil bacteria to absorb atmospheric nitrogen and thus reduce the need for commercial nitrogen fertilizers. Nitrogen from these legumes is a way to reduce the application of synthetic nitrogen fertilizers.

“The main concern is that there is still a lot of research to be done for proper vaccinations for guar,” Ravelombol said.

A number of beneficial microorganisms or inoculants can be introduced into the soil or seeds, but not all of them are optimal for guar.

“Existing vaccinations for soybeans, peanuts and peas. Their effectiveness in fixing nitrogen in guar is still in doubt, ”he said.

Ongoing tests of a wide range of existing vaccinations will determine what can be adapted for guar, Ravelombol said. He said they hope to narrow that range in a year or two.

“There may be different vaccinations that work differently on different varieties,” he said. “We want to understand the genetic basis of nitrogen fixation – the reaction to the addition of an inoculant based on both vaccinations and guar genotypes.”

That the guar crop matched the season

Another goal is to develop a short-term guar that will be harvested by September, when it is planted in mid-June.

“A 90-day guar would be ideal for crop rotation with wheat, especially if the wheat is grown for double grazing and cereals,” Ravelombol said.

The AgriLife Research program has breeding lines for the Texas environment, but he said it is also testing the USDA germplasm resource information network lines to find any adapted to Texas conditions.

It may take five years to develop a short-lived variety, and he started evaluating these breeding lines only last year. The process will be repeated this year, and then advanced yield tests will be included in the next three years.

The market exists, processing nearby – no

Although farmers are in no hurry to adopt guar, Ravelombol hopes this will change when the study is completed and distributed by producers.

“We know that guar is a wonderful sevarat culture,” he said. “It can help diversify the region’s cultivation systems. It is also a profitable crop to grow. ”

Trostl said the study helps prepare for the day when a favorable economy will return for U.S.-grown guar.

Although guar is an annual US $ 1 billion import market, international production has been cheap since about 2014, making it difficult to compete with U.S. agriculture and processing, especially when prices for other crops such as cotton , grains of sorghum and sesame, equal to or close to record highs.

However, if guar production resumes in the U.S., farmers may be able to insure the crop.

Trostle is currently working on a subcontract with the USDA Risk Management Agency to develop guidelines for assessing guar damage and subsequent crop potential.

“This process began in 2018 with meetings of producers in Brownfield and Vernon,” said Trostl. “Farmers at these meetings have shown that crop insurance will allow them to easily double their acreage.”

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