Despite climate change and variability across Australia’s grainbelt, with increased ambient carbon dioxide (CO2) and temperature and reduced rainfall, very little attention has been paid to the interactive effects of high temperature, CO2 and soil moisture on crop growth and yield.
That’s about to change thanks to experiments by CSIRO Plant Industry and The UWA Institute of Agriculture at The University of Western Australia (UWA), with a research team at UWA’s Shenton Park Field Station using four state-of-the-art poly tunnels to inform wheat breeders about how climate change and variability will affect the genetic traits they select for.
The sealed tunnels were designed and built as part of the ‘Climate Ready Cereals’ project funded by the Federal Department of Agriculture, Forestry and Fisheries (DAFF) and the WA component is managed by CSIRO in collaboration with The UWA Institute of Agriculture.
According to CSIRO Principal Research Scientist Dr Jairo Palta, most previous studies showed individual effects on wheat yield of increased CO2, higher temperature and drought, but was unclear about how the three variables interacted and affected grain yield for different cultivars.
“The CSIRO and UWA research team should unravel the impact of this interaction during wheat growth and the critical stages of flowering and grain filling,” Dr Palta said.
Tunnel temperatures vary from ambient to six degrees celsius above ambient and CO2 levels vary from ambient (approx 380ppm) to about double at 700ppm.
WA, Australia’s largest grain-producing state, is forecast to become drier, while all regions will likely be exposed to higher temperatures and elevated CO2.
The UWA Institute of Agriculture Director, Winthrop Professor Kadambot Siddique, said that grain productivity and quality must be sustained or increased in the face of increasing demand for food, stockfeed and fuel for WA to maintain its cereal supplies and competitive export status.
“Based on current physiological knowledge, some wheat germplasm, contrasting for traits, will likely differ in yield response to climate change and variability,” Professor Siddique said.
According to Dr Palta, while elevated CO2 had some advantages for crops such as wheat, it was likely to suffer yield loss from increased temperature and frequency of terminal drought.
The UWA Institute of Agriculture and CSIRO PhD candidate from Brazil, Eduardo DIAS de Oliveira, is doing most of the ‘hands-on’ physiological research in the UWA climate tunnels.
Mr DIAS de Oliveira said that growing different wheat genotypes in environments with elevated CO2 and temperatures and controlled water, then analysing growth (size, leaf area, biomass), physiology (photosynthesis, transpiration, water use) and yield and studying how these mechanisms worked inside the plants, would help breeders select and create traits better adapted to climate change and variability.
The UWA Institute of Agriculture post-doctoral Fellow, Dr Helen Bramley and Australian Endeavour Research Fellow, Dr Muhammad Farooq, from the University of Agriculture, Faisalabad, Pakistan, are researching high temperature and drought, which complements the ‘Climate Ready Cereals’ project.
Dr Bramley explained that water, although fundamental to plant growth and productivity, was usually the most limiting resource, especially in dryland agricultural environments.
“Water is the bulk constituent of most plant cells and is needed for biochemical processes, cell expansion or growth, dissolution of many compounds and conveying essential nutrients.
“Although dryland crop plants, such as wheat, have evolved mechanism to conserve water, when taking up CO2 for photosynthesis water vapour is lost via evaporation through open stomata.
“This water must be continually replenished from water taken up from the soil by roots, to prevent the shoot from dehydrating,” Dr Bramley said.
According to Professor Siddique, Dr Bramley’s UWA post- doctoral project, ‘Linking the plumbing of roots to shoots: wheat plant hydraulics under drought’, is making a valuable contribution to the ‘Climate Ready Cereals’ project.
Dr Farooq is evaluating the role of nitric oxide (NO) in heat and drought stress resistance in wheat. NO is emerging as an important signalling molecule, with multiple biological functions.
“I am assessing the genotypic variation in terms of stress-induced NO emission and the relationship between NO emission, heat and drought,” he said.
Dr Farooq’s findings should background the mechanism of NO-induced stress tolerance in wheat and help develop a quick test to screen genotypes for stress resistance.
About 21% of the world’s food depends on wheat (T. aestivum), which grows on 200 million hectares of farmland worldwide. While wheat’s global yield rose 20% from 1987 to 1997, a
1% decline from 1997 to 2007 meant it would struggle to sustain global population increases.
