Promoting healthy biomes in China’s rice supply

Human disturbances are endangering microbial species crucial in the role of food production in China, writes Rebecca Borg.

Rice is a major crop in Asia, being a staple part of the diet in most households. In China in particular it is the most important crop, taking up 25% of the cultivated farmland, and representing 30% of the world’s rice supply.

A healthy biome in soil is crucial in the cultivation of rice and can have significant repercussions to the viability of the environment, including increased emissions of greenhouse gas methane and the inability for soil to self-purify to remove pollutants.

“You can’t overstate the importance of rice, and rice paddies are at risk of pests, parasites and disease - there’s a lot that can go wrong,” says Ashley Franks, a Pro-Vice Chancellor (Research Capability) and Professor of Microbiology at La Trobe University. “The environment needs to be able to conduct all the natural processes to ensure the nutrient cycle, provision of energy, and growth is supported. Without this balance you lose production, which could have significant implications for the world’s food supply.”

Professor Franks is collaborating with colleagues at La Trobe University as well as researchers from Zhejiang University in Zhejiang, China.

“Rice is grown widely throughout Zhejiang province, making Professor Yan He and her team the ideal collaborators in this project,” says Professor Franks. “We wanted to examine the factors that affect diversity in the rice paddy and how this can help improve crop production, and examine the feedback look between soil, nutrients microorganisms and plants. Our partners in Zhejiang are doing the cultivation and growth in this study, while we at La Trobe are helping them with analysis and bioinformatics.”

Paddy soil samples were collected from paddy fields in Jiaxing city in Zhejiang, China. These fields are typically used to grow and harvest rice crops, with the partially flooded conditions perfect for growing semi-aquatic rice varieties. The floodwater and groundwater used for the cultivation of rice aids water purification, oxygen generation and temperature regulation. However, the increasing use of insecticides to preserve rice growth has contributed to the loss in microbial diversity and endangered wetland species as a result.

“If the flooded rice paddy soils are not given a good balance of nutrients and carbon and maintained in a healthy state, this will lead to a loss of biodiversity and new bacteria,” says Professor Franks. “This means they can’t degrade pesticides, leaving them vulnerable to toxic buildup which can be detrimental to not just plants, but also people who eat it.”

Although this research provides an in-depth analysis of the consequences imposed by biodiversity loss in soil within terrestrial ecosystems, Professor Franks says future studies should analyse how microbial diversity loss impacts other soil functions within different environments.

“A bacterial community is more than the sum of it parts, and the important thing is not just to know what bacteria is there, but how they are functioning together. By studying this we can promote these interactions, leading to healthier biomes and increased rice productivity.”