By Matt Shipman
Climate change is making droughts more common and more severe—which makes research into developing drought-resistant crops more important than ever. Now researchers have developed a new framework that should expedite this important research.
One of the challenges in crop breeding is that researchers have to take meticulous measurements of hundreds (or thousands) of individual plants across many different experimental breeding plots in order to assess which plant strains have the most desirable characteristics (and therefore would make good candidates for future crops). This process is both tedious and time-consuming.
But a research team led by Frank Bai has developed a framework for measuring some of these phenotypic traits that should speed things up. Bai, an assistant professor in NC State's Department of Biological and Agricultural Engineering, recently published a paper in the journal Field Crops Research outlining a new framework for rapidly assessing two key drought-resistant traits in crop research plots. We talked to Bai to learn more.
What's the fundamental big idea in your new paper?
The big idea is to develop an easy-to-use sensing and modeling system to enable accurate, automatic, and high-throughput screening of evapotranspiration (ET) and water use efficiency (WUE) for individual breeding plots for plant breeders and scientists. ET refers to water loss through soil evaporation and plant transpiration (where water evaporates as plants "exhale" mainly through the stomata on their leaves). WUE refers to how much biomass is gained per unit of water applied to a crop.
Breeding plots are sections of a field set aside for breeding plants. When it comes to research into developing new strains of a crop, breeders often make use of smaller plot sizes so that they can include a large number of candidate genotypes (or breeding lines) in a limited area. This means that these plots are quite small, compared to production-scale field experiments. In the research we did for this paper, we focused on experimental breeding plots for corn—each plot was 6.1 meters long and 4.6 meters wide.
Measuring ET and WUE with conventional techniques means going to each plot and taking a variety of painstaking measurements—using portable instruments to measure parameters or taking field notes of individual leaves and so on. This is incredibly time-consuming, and the measuring speed (or throughput) is low.
Our goal with this work was to develop an approach that is much quicker, without sacrificing accuracy.
Existing high-throughput tools that measure phenotypic traits focus on morphological traits (e.g., canopy height and aboveground biomass) and traits that can be measured using spectral imaging technologies (e.g., Normalized Difference Vegetation Index). Some of these traits can be related to the plot-scale WUE. Our approach directly estimates WUE by combing morphological and spectral phenotyping with physical ET models.
From a farmer's standpoint, why is this important?
Ultimately, this will help us breed better seeds to deal with drought events.
In addition, since plant transpiration is one of the most important physiological processes in plants, and is coupled with photosynthesis activity, our tool will be valuable in precision field management by mapping crop stress for farmers.
Okay, so how exactly does this help researchers who are trying to breed drought-resistant crops?
With this screening tool, breeders will be able to quickly select the top genetic lines without labor-intensive field scouting. In other words, they can figure out which breeding plots contain plants that have the most desirable characteristics in terms of drought tolerance.
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