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An interdisciplinary look at roots to improve crop productivity on hard soil

Last changed: 23 August 2019
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Dry and compacted soils make it more difficult for roots to grow. Root growth is slower and requires more energy, which eventually leads to reduced crop productivity. A team of SLU researchers, consisting of both plant and soil scientist, are working on the adaption of crop roots to these conditions. Using wheat as a model plant, they identified root traits that may contribute to higher yields under drought and compaction.

Hard soil: an emerging threat to crop production

Dry and compacted soils have one key thing in common: They are hard. In hard soil, root growth slows down and requires more energy, i.e. plants require more time and need to invest more carbohydrates to reach vital soil resources.

Ultimately, plants cannot acquire enough water and nutrients, and the amount of carbohydrates available for aboveground growth decreases, which results in low crop productivity. Yield limitations due to hard soil are already a prevalent problem in today’s agriculture and will likely aggravate in the future.

Dry spells will increase in their frequency and severity due to climate change, while agricultural mechanization involving heavy machinery will increase the acreage of compacted arable land.

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Illustration: Tino Colombi.

Adapted roots: a possible solution to enhance tolerance to hard soil

In our research, we aim to unveil phenotypic root traits and identify underlying genes that i) enable plants to grow faster in hard soil and ii) reduce the carbohydrate requirements for root growth. Based on this information, plant breeders can develop novel varieties with superior performance on hard soil. To achieve this, we combine latest approaches from different disciplines such as plant physiology and soil science, computer vision as well as plant genetics. Using wheat as a model plant, we could identify possible phenotypic selection targets. A pointy root tip shape facilitates root growth in hard soil, while large root cells reduce the carbohydrate cost of root growth. During the coming months, we will set up a new series of experiments in order to identify target genes that are involved in the regulation of root growth rate and carbohydrate requirements of root growth in hard soil.

The next step: getting out of the laboratory

So far, we conduct our research under controlled conditions with seedlings that are just a few days old. Working at such a small scale enables us to pinpoint very specific aspects of root growth in hard soils, which would not have been possible with older plants. However, field tests are necessary to verify whether selecting for the identified root traits and the underlying genetics will lead to novel varieties with improved crop performance and yield on hard soil.

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