Research finds rice grain quality improves when grown using water saving methods

By Rodney Woods

Charles Sturt University PhD research has found rice grain quality is improved when the crop is grown using water saving methods, increasing profit per megalitre.

The research, by Rachael Wood from the Australian Research Council Industrial Transformation Training Centre for Functional Grains, is good news for rice growers facing record low water allocations.

Dr Wood said her PhD examined the impact of crop management practices such as nutrient management, irrigation timing and planting density on rice grain quality in the Riverina.

“Reducing water usage without impacting crop yield and grain quality is a significant challenge for the Australian rice industry,” she said.

“One of the strategies adopted by growers to improve their irrigation efficiency has been to delay the permanent watering of the crop.

“A comparison of this water saving technique with conventional irrigation methods revealed at nitrogen fertiliser rates above 60 kilograms per hectare, the whole grain yield was higher when the permanent water was delayed.

“WGY (whole grain yield) is the primary method used in assessing grain quality for the rice industry and is incorporated into grower payments.”

The research has also shed new light on the impact of the rate and timing of fertiliser applications.

Dr Wood said increasing the rate of nitrogen fertiliser applied pre-permanent water significantly increased WGY in all tested varieties, but the effect of splitting the same total nitrogen rate into two applications or applying the fertiliser mid-season at panicle initiation was variety specific.

“The treatments with the highest economic return did not always match the highest WGY,” she said.

“Importantly I also found that nitrogen fertiliser treatments with the highest profit per hectare also had higher total protein content, increasing the hardness of cooked rice and lowering the eating quality.

“To encourage the production of high quality grain the rice industry should consider putting higher premiums on grain with improved quality parameters, such as low protein content, which could also help reduce the excessive use of N fertiliser.”

Dr Wood also found that increasing the zinc content of the grain through fertilisation would not affect grain quality but might improve the zinc level delivered to consumers, which could deliver benefits for human health.

Throughout her research Dr Wood was based at the NSW DPI Yanco Agricultural Institute, where she worked with experts from the NSW DPI rice team.

She was supervised by Professor Chris Blanchard and Associate Professor Dan Waters from Charles Sturt, Brian Dunn and Dr Prakash Oli from NSW DPI and Professor John Mawson from Plant and Food Research in New Zealand.

Dr Wood’s research was supported by a scholarship from the Industrial Transformation Training Centre for Functional Grains.