How can annual crops be converted into perennial crops?

Most staple grain crops are annuals, replanted every year after the field has been cleared. Perennial versions that regrow from the same roots for several years could save labour and protect soil, if they can match the yields of annual crops.

Question

How can annual crops be converted into perennial crops that regrow and yield for several years from a single planting? This covers breeding routes (hybridising crops with perennial relatives, domesticating perennial wild species), the genetics of regrowth and longevity, and whether perennial grains can keep yield, grain quality and profitability across environments.

Background

The question is in the theme "exploring resources and technologies for breeding" of the 100 essential questions for the future of agriculture, compiled from 419 questions submitted worldwide in 2022 [1]. Perennial grains attract interest because annual cropping requires the yearly clearing of vegetation, which leads to soil erosion and other degradation [2].

What is known

• Perennial rice, bred by crossing Asian rice with its perennial African relative Oryza longistaminata, gave eight consecutive harvests over four years from one planting, averaging 6.8 t per hectare per harvest against 6.7 t for replanted annual rice. Soils gained 0.95 t of organic carbon per hectare per year, farmers saved 58% of labour and 49% of input costs in each regrowth cycle, and in 2021 it was grown on 15,333 hectares by 44,752 smallholders in southern China [3].
• A review of perennial wheat, rice, maize, rye and sorghum highlights benefits for soil, nutrients and farm costs, but names maintaining perenniality without losing genetic diversity as a major challenge [4].
• In wild rice, the locus EBT1, a tandem pair of microRNA156 genes, drives the floral reversion and vegetative propagation behind perennial growth; combining it with two genes for prostrate growth gave rice lines with a robust perennial habit [5].

What would count as progress

No single result settles a question like this; contributions like these would move it forward:

• Multi-year, multi-site yield trials of perennial lines against annual checks, including how yields change over successive regrowths, with the data released openly.
• Field trials of lines carrying identified perenniality genes, such as rice EBT1, that measure regrowth, yield and grain quality over several seasons, and searches for equivalent genes in other cereals.
• Life-cycle and economic analyses of perennial systems over their full lifespan, including soil carbon, labour and replanting costs.

References

1. Hu, Y. et al. (2023). 100 essential questions for the future of agriculture. Modern Agriculture 1(1), 4–12.
2. Crews, T. E. et al. (2018). Is the future of agriculture perennial? Imperatives and opportunities to reinvent agriculture by shifting from annual monocultures to perennial polycultures. Global Sustainability 1, e11.
3. Zhang, S. et al. (2023). Sustained productivity and agronomic potential of perennial rice. Nature Sustainability 6(1), 28–38.
4. Soto-Gómez, D. & Pérez-Rodríguez, P. (2022). Sustainable agriculture through perennial grains: wheat, rice, maize, and other species. A review. Agriculture, Ecosystems & Environment 325, 107747.
5. Dai, B. et al. (2026). Resetting of a tandem microRNA156 enables vegetative perennial growth in rice. Science 391(6791), 1239–1245.

Source

Imported from 100 essential questions for the future of agriculture, question 37, curated by Hu et al. Listed as open in the source (2023) and still an active research question as of 2026-10-20. The statement above is written in our own words; see the source for the original wording, history and discussion.