Drought-tolerant chickpeas that are highly efficient at extracting water from the soil are on the drawing board, with researchers employing novel technology to speed their search of available genetic material.
As part of research conducted with Grains Research and Development Corporation investment, Helen Bramley — a senior lecturer at the University of Sydney — and her research team have developed a new way to quickly screen chickpea genotypes for water-use efficiency.
The aim is to reduce the time taken to release drought-tolerant chickpea varieties to growers.
“The traditional approach involves inserting aluminium access tubes into the soil to measure soil water content using a neutron probe,” Dr Bramley said.
“But installing the tubes and taking the measurements at different depths is time-consuming and labour-intensive.”
Accordingly, the team was keen to find a more accurate and efficient, less time-consuming and non-destructive method for gathering water-use data across a large population of trial plots at critical periods.
“I saw the University of Sydney Professor of Digital Agriculture and Soil Science Alex McBratney give a presentation that described various technologies for measuring the soil properties, which included electromagnetic induction,” Dr Bramley said.
“EMI measures the apparent electrical conductivity of soil or how salty the soil is.
“Because there is generally a relationship between ECa and moisture content, I asked Professor McBratney if it was possible to adapt the technology to measure soil water use in chickpea plots — he said it could be possible.”
Subsequently the team used an EM38-MK1 sensor, a one-metre-long instrument capable of collecting electrical conductivity data. A model, calibrated against neutron probe measurements, was also developed to calculate available soil water for different depths within the soil.
At the end of 2017, a proof-of-concept experiment was established using 36 different chickpea genotypes.
Some were rain-fed while others were irrigated because of dry seasonal conditions.
“Using the EM38 sensor, we were able to calculate water use for the plants in every plot as well as at different soil depths after a rainfall event,” Dr Bramley said.
“Being able to measure moisture at different depths allowed us to pinpoint where in the soil the plants were extracting water from.”
As a consequence, Dr Bramley said the technology had enabled the team to identify the chickpea genotypes with deeper roots, which may be one of the traits important for drought tolerance.