Earlier podding may lift chickpea resilience

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Purushothaman Ramamoorthy, Sarah Purdy and Angela Pattison with some of the chickpea lines they are assessing for drought and heat-tolerance traits.
(From left) Purushothaman Ramamoorthy, Sarah Purdy and Angela Pattison with some of the chickpea lines they are assessing for drought and heat-tolerance traits.
PHOTO: Liz Wells

Research at the University of Sydney’s I.A. Watson Grains Research Centre is using field trials, molecular science, data analytics and neutron probes to find genes that can improve the ability of chickpea cultivars to withstand drought and heat stress.

Earlier podding is shaping up as a way to help chickpeas yield better in periods of terminal stress, and a University of Sydney research team is hoping for a typical growing season in 2018 to test out the promising cultivars it identified in the project’s first two wildly different years.

The project is funded by the GRDC and the Australian Research Council (ARC), and is part of the Legumes for Sustainable Agriculture ARC Industrial Transformation Research Hub.

The project is examining about 1250 chickpea cultivars from Australia, Ethiopia, India’s International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Iran and other locations, as well as some of chickpeas’ (Cicer arietinum) wild relatives, in its search for improved heat and drought-tolerant genetics.

Plant breeder and agricultural scientist at the University of Sydney Dr Angela Pattison is part of the team, and is homing in on some varieties with promising heat-avoidance traits picked out of delayed-sowing experiments in 2016 and 2017 at the I.A. Watson Grains Research Centre at Narrabri, New South Wales.

Dr Pattison has distilled the initial genetic pool down to a subset of roughly 200 promising lines, which were increased in 2017 and will be undergoing field-based screening in 2018.

“We had a wet and cloudy 2016, followed by a dry and frosty 2017, so we’re hoping for a season that’s less extreme this year,” Dr Pattison says.

Heat stress can damage plant tissue, shorten flowering and podding periods, reduce pod-set, and prompt production of heat-shock proteins.

“All these factors can impact yield as well as quality, and the Australian chickpea industry is looking for genetics that withstand terminal heat stress and build on the disease-resistance capability of commercial cultivars.”

The 2016 and 2017 trials featured a typical May–June sowing date and a late July slot, which increased the likelihood of selected lines running into heat stress, a trigger for prompting chickpea plants to flower.

Traits in lines that could bolster yields include flowers with above-average heat tolerance, fast-filling pods and increased radiation use efficiency.

“We have developed a genetic mapping population using a line from India with pollen that can withstand higher temperatures. We hope this will allow creation of a genetic marker for heat-tolerant flowers, which can help find heat-tolerant lines in a cheaper and faster way,” Dr Pattison says.

“Selection among diverse genotypes will be made for a host of other traits, including earlier pod-set, which is likely to lead to yield gains.”

The most promising lines will be crossed with high-yielding Australian cultivars and sent to the Pulse Breeding Australia chickpea breeding program at Tamworth, NSW, for incorporation into future chickpea cultivars.

Looking deeper

The chickpea physiology research is being led by the university’s Dr Helen Bramley, who says the program’s strength comes from its ability to look at the chickpea plant holistically.

“Observations about flowering and podding are important in any pre-breeding program, but optimising their timing is only part of the story for improving productivity,” Dr Bramley says.

“Understanding the physiology – the functions and processes within plants – enables us to explain environmental responses, identify adaptive mechanisms and develop phenotyping tools to help pre-breeders and breeders select the right parental material.”

To do this, the project is using a range of complementary techniques, from lab-based analyses to controlled-environment and field-level measurements.

“While we are focusing on important traits such as roots and biochemical profiles, we have used the past two contrasting seasons to our advantage to examine phenotypic plasticity.”

Chickpeas are renowned for their variable growth and yields, and Dr Bramley says the project has already identified stability in some genotypes.

“By simulating the contrasting environments in the glasshouse we are beginning to understand what drives these differences.”

Drinking habits

Dr Purushothaman Ramamoorthy came to the I.A. Watson Grains Research Centre from ICRISAT last year and is looking at chickpea root traits and their contribution to efficient soil-water use under drought conditions.

Dr Ramamoorthy says neutron probing is being used in the field trials to assess a wide range of germplasm, including locally adapted and non-Australian cultivars and chickpeas’ wild relatives, for their water-use habits.

From these, several chickpea lines with contrasting levels of crop-water use will be examined to identify the traits and mechanisms that govern their total water use.

“Chickpea genotypes with greater early vigour and which use a greater proportion of their total water during podding tend to yield better under late-season or terminal drought stress.

“The identified physiological traits and mechanisms associated with effective water use would further assist in developing elite cultivars with better adaptation to drought-prone environments,” Dr Ramamoorthy says.

Cholesterol for plants

Dr Sarah Purdy, also at the University of Sydney, is looking at the biochemical composition of chickpea varieties to identify chemical signatures that can be used to indicate how a new variety will perform under drought.

“The idea is to look at the chemical profile of the plant when it’s growing happily and healthily to predict how it will perform under future stress.”

Dr Purdy says different lines have different proportions of metabolites, such as soluble sugars, starch, and amino and organic acids, which have the potential to be chemical indicators of drought tolerance.

“In the same way that blood cholesterol is used by general practitioners to predict cardiac risks in people, I want to find the biochemical predictors for drought risk in chickpeas,” Dr Purdy says.

Some promising markers from the 2017 growing season have been identified, which Dr Purdy aims to validate this year on about 300 new chickpea lines.

GRDC Research Code US00083

More information:

Angela Pattison

Helen Bramley

Purushothaman Ramamoorthy

Sarah Purdy
0477 738 776