Advances In Remote Sensing Aid Wheat Variety DevelopmentFri, 09 Jul 2021 09:52:13 CDT
Gopal Kakani, unmanned aerial systems phenotyping expert with Oklahoma State University’s 12-member wheat improvement team, is expanding the use of drones mounted with high-resolution cameras to monitor, evaluate and compare new breeding lines.
Drones of various sizes and configurations are increasingly being used to monitor crop conditions. Current and future investments in drone-related research will help bring down the cost of the technology for the benefit of both farmers and university research programs, according to Gopal Kakani, who works as a plant physiologist with the wheat breeding team at Oklahoma State University.
Technological advances that allow scientists to peer inside the genes of a wheat plant far outpace the progress plant physiologists have made at examining complex biological processes using high resolution imaging, but that is starting to change as more research funding becomes available.
Gopal Kakani, an unmanned aerial systems phenotyping expert with Oklahoma State University, is working to expand this new frontier.
“Since my childhood growing up in India, I was always fascinated by science, and I had a passion for research,” he said recently. “I wanted to help people, either through medicine or by feeding them. I took the route of feeding people by getting involved in agriculture.”
As a member of the wheat improvement team at OSU, Kakani measures a wide range of physiological characteristics at various growth stages across more than 2,000 wheat variety test plots statewide. Features like plant height or leaf length or forage tonnage can often be measured the old fashioned way, with rulers or scales. But collecting that data is cumbersome and time-consuming, reducing its effectiveness for analysis and selection.
“We can hire students to measure all of this data, but it takes a significant amount of time in the field, and all of those measurement can’t be taken on the same day,” he explains. “During the two or three weeks it takes to go from plot to plot, the wheat grows rapidly, and it’s hard to capture information in a way that would allow for a true comparison between varieties.”
By contrast, unmanned aerial systems, sometimes referred to as drones, can be flown 200 feet above the crop canopy with high-resolution cameras and pick up minute details down to the square centimeter in a single pass.
Sensors detect light that is not visible to the human eye as it reflects off of the plant material, creating what Kakani calls “a reflectance signature,” which is then ripe for further analysis.
“This technology allows us to keep taking snapshots of what’s happening with the plant on a daily basis, sometimes even multiple times within the same day,” he said. “We can look at things like how plant photosynthesis responds to light or how it uses nitrogen.”
Expanding imaging capabilities
J.B. Stewart farms in Cimarron County, west of Guymon. He is a cooperator with Kakani on a federally funded three-state research project to collect data on greenhouse gas emissions from agriculture and demonstrate how improved management practices can reduce — or even reverse — any negative atmospheric impact.
This spring Kakani’s team installed ground-based sensors on an 85-acre parcel of non-irrigated grain sorghum on Stewart’s farm, with the goal of establishing the underlying metrics to support wider use of carbon credits to reward farmers for environmentally beneficial farming practices.
“I like to work with cutting edge things and see what it will do for us,” Stewart said of why he chose to participate. “There’s some astonishing technology available, and it’s just a matter of putting it to use.”
Using this same remote sensing technology to help develop new varieties with improved water and nitrogen use efficiency could prove extremely valuable in the panhandle, which has a uniquely challenging production environment, Stewart said.
In recent years, he has watched yields on his own farm swing from 80 bushels per acre in 2019 all the way down to 11 bushels per acre the following year, all on the same variety. The main challenge is the high altitude, combined with erratic rainfall and frequent wind.
Stewart already benefits from remote imaging technology by using a mobile app called FarmLogs to track information about weather, soil type, pest infestations and more. But on the slim profit margins he makes from dryland farming, advanced sensing tools are cost prohibitive, he said.
That’s a concern among research programs too, according to Kakani. He’s hoping more federal investment in remote sensing will help bring down costs in a way that mirrors prior investment in genetic sequencing. It cost $3 billion to sequence the first human genome, he points out, but now labs can generate an entire genetic sequence in a day or two for around $1,000, a breakthrough enabled by that initial public investment.
Basic improvements still needed
Hyper-spectral cameras were initially developed for geological applications and still need modification to become better suited to crop analysis, Kakani said. They are also heavy and expensive, and the amount of data they generate — 50 gigabytes from a single 15-minute flight — requires advances in artificial intelligence and machine learning methods to process more efficiently, he adds.
For the past six years, Kakani has been using a handheld thermal remote sensor to identify heat and drought tolerant traits in wheat that can then be correlated with genetic markers. Now he’s ready to see broader aerial imaging take flight.
“We approached Oklahoma Agricultural Experiment Station leadership a couple of years ago with a proposal to purchase a state-of-the-art hyper-spectral drone that would really allow us to get our foot in the door in modern phenotyping research,” he recalls. “They funded the purchase and set us on this path of increasing our capacity for this type of cutting edge research.”
Starting this year, he and a team of graduate assistants will use the new drone to map the early season crop canopy of wheat variety trials. This data will help them evaluate how the varieties perform in a dual-purpose system aimed at producing forage and grain, an important double-crop option in the Southern Plains.
Down the road, Kakani plans to apply the same technology to gauging nitrogen and water use efficiency and, eventually, pest tolerance. Sensors can detect the tissue concentration of phenols, naturally occurring biochemical compounds that protect plants against insects.
Such compounds are important for another reason. They appear to influence the health attributes of the grain, according to OSU’s chief wheat breeder Brett Carver.
He and other researchers on campus have already done preliminary studies showing wheat with higher concentrations of phenols in the bran result in flour with enhanced antioxidant activity. The purple-colored phenols are the same flavonoids that make blueberries so nutritious.
Optimizing inputs brings multiple benefits
Back in the panhandle, Stewart said he looks for more than yield potential when selecting varieties. Grain quality is something he monitors closely. He stores most of his wheat in on-farm bins, which gives him the option of selling directly to flour mills.
His three favorite varieties — Iba, Breakthrough and Showdown, all of which were developed at OSU — offer exceptional milling and baking quality.
Efficient use of inputs, enabled in part by OSU’s wheat breeding efforts, has an important quality component, because it effects the expression of protein and other nutrients in the kernels.
For Kakani, however, it’s the environmental benefits that stand out. After all, what initially drew him to OSU was the chance to work on renewable agricultural systems.
“If the wheat plant is more efficient and is able to use all of the nitrogen we apply, then none of that nitrogen escapes into the atmosphere,” he said.
“We want to take the results from one plant, selected in our breeding trials, and apply it across hundreds of acres,” he adds. “When we look at that same variety on a broad scale, are we getting the same results? That’s why field level measurements using remote sensing are so important.”
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