Acid soil tolerance in chickpea
- Moderately acid soils and aluminium toxicity limit the expansion of chickpea production in Western Australia.
- Wild chickpea relatives have demonstrated some improved tolerance to low pH and aluminium toxicity and may hold the key to future improved varieties.
A lack of tolerance to acid soils is limiting the expansion of chickpeas from their traditional neutral to alkaline soil types into new growing areas.
In moderately acid soils, with pH below 5.5 (CaCl), plant growth can be restricted by either aluminium and manganese toxicity.
Aluminium toxicity is more common in Western Australia and manganese in the east.
Deficiencies of molybdenom, nitrogen, phosphorus, calcium and magnesium can also be a factor.
Wild relatives of the cultivated chickpea (Cicer arietinum) may hold the genetic keys to overcoming these limitations.
Search for tolerance
With GRDC investment, researchers at Murdoch University, in WA, have set their sights on finding genetic tolerance to low pH sandy soils, with an emphasis initially on overcoming aluminum toxicity.
Murdoch University is also developing a screening method for tolerance to manganese toxicity in wild Cicer.
Aluminium toxicity inhibits cell division and reduces root elongation of plants preventing the plants from sourcing both nutrients and water. Severe symptoms include brown stubby roots and decreased fine branching.
The Murdoch University project is part of an Australia-wide multi-agency search for wild chickpea relatives with tolerance to abiotic stresses, such as drought, heat, cold and acidic soils, as well as disease stresses from ascochyta blight, Phytophthora root rot and root lesion nematode.
Aluminium toxicity in acid soils in Western Australia reduces chickpea root length.
The researchers are tapping into an international search for wild relatives.
Both C. reticulatum (the progenitor of chickpea) and C. echinospermum can interbreed with domesticated chickpea and, just a few years ago, there were less than 30 accessions available in international genebanks.
Between 2013 and 2015, CSIRO's Dr Jens Berger and an international team of collaborators explored South Eastern Turkey using resources from GRDC investment and a slate of international sponsors.
Seed-collecting missions often have researchers crawling across rugged countryside to collect even the tiniest of sample of mature seed.
Leaves were collected from plants for genomic analysis by the University of California, Davis (UC Davis), which provided a full description of genetic diversity within the collection.
Knowledge of the collection's diversity provides a roadmap to prioritise the material for further analysis.
Wild relatives of the cultivated chickpea collected from Turkey may hold the genetic keys to improving acid soil tolerance.
In a time-consuming process in Turkey, the 600 samples collected were grown out to increase the number of seeds, with the help of Harran University, and placed with the genebank at the Aegean Agricultural Research Institute.
Seed was transferred to Australia, where it is being grown under quarantine at the Australian Grains Genebank before being bulked and distributed for screening.
Low pH tolerance
The team at Murdoch University has now screened just under 200 of the wild Cicer collected in 2013 for tolerance to low pH and aluminium tolerance.
Using a measure of root growth, they've already identified tolerance to both low soil pH and increasing concentrations of aluminium in this first batch of wild Cicer (see Figure 1).
The next step is to compare sensitive and tolerant wild Cicer accessions in field trials in 2019, across a range of soil textures. Each trial will have sites with different soil texture, pH and aluminum content.
There are still more lines of wild Cicer that were collected from different areas of Turkey in 2014 and 2015 that will be screened to increase the breadth of genetic diversity.
In a parallel project, Professor Doug Cook, at UC Davis, and Professor Kassahun Tesfaye, at Addis Ababa University in Ethiopia, are exploring chickpea for tolerance to aluminum-rich, acid soils.
Their efforts focus on two germplasm sources:
- Landraces from acid soil regions in Ethiopia, which is an ancient center of chickpea's secondary diversity; and
- Advanced generation hybrid populations from a five-year effort to introduce genes from the wild collection into cultivated backgrounds.
These efforts provide an alternate source of genetic adaptation that could help Australian farmers.
The ultimate aim of the program is to enable acid-tolerant wild Cicer and rhizobia to enter Australia's chickpea breeding programs in the future.
GRDC Research Codes UMU00044, CSP00185, UCD1804-001RTX
More information: Dr Wendy Vance, Murdoch University, 08 9360 7224, email@example.com