Sustained productivity and agronomic potential of perennial rice

Abstract

There is an urgent need for agricultural systems to intensify sustainably, increasing crop productivity, farmer livelihoods and soil health while using fewer resources. Crop perennialization, the conversion of especially annual grains to perennial forms, has shown such possibility. Here we report the successful breeding of perennial rice and assess its performance and potential. Domesticated, annual Asian rice (Oryza sativa) was hybridized with its perennial African relative Oryza longistaminata. From a single planting, irrigated perennial rice produced grain for eight consecutive harvests over four years, averaging 6.8 Mg ha−1 harvest−1 versus the 6.7 Mg of replanted annual rice, which required additional labour and seed. Four years of cropping with perennial rice resulted in soils accumulating 0.95 Mg ha–1 yr–1 organic carbon and 0.11 Mg ha−1 yr−1 nitrogen, along with increases in soil pH (0.3–0.4) and plant-available water capacity (7.2 mm). Perennial cultivars are strongly preferred by farmers; growing them saves 58.1% of labour and 49.2% of input costs in each regrowth cycle. In 2021, perennial rice was grown on 15,333 ha by 44,752 smallholder farmers in southern China. Suited to a broad range of frost-free environments between 40° N and 40° S, perennial rice is a step change with potential to improve livelihoods, enhance soil quality and inspire research on other perennial grains.

Convergent evolution of the annual life history syndrome from perennial ancestors

“…However, progress in breeding perenniality into annuals has been hampered by limited knowledge of the developmental, physiological and genetic mechanisms underlying growth habits in different plant groups, as well as potential trade-offs between production and longevity. A notable exception is the ‘perennial rice’ hybrid that has consistent yield across five years of growth in southern China ( Zhang et al., 2022 ). The fact that annuals and perennials are often closely related suggests that only small genetic differences differentiate them ( van Kleunen, 2007 ).…”

“…Moving forward, a particularly intriguing system for understanding variation in senescence-based lifespan is the perennial rice hybrid O. sativa x O. longistaminata . Unlike annual O. sativa , this hybrid can produce abundant twice-yearly harvests for up to four years, resulting in significantly easier, cheaper, and more sustainable farming ( Zhang et al., 2022 ).…”

Prospects for rice in 2050

“…However, O. rufipogon (the ancestor of Asian rice) is perennial. Due to "one-sowone-harvest" nature, annual rice is not sustainable in many aspects, and particularly vulnerable to changing climates; Due to a more extensive root systems and greater assimilate reserves, perennial rice can better cope with abiotic stress and grow better in more marginal landscapes (Zhang, Huang, et al, 2023). Currently three perennial rice cultivars (PR23, PR25, and PR107) produced by crossing of annual Asian rice with its perennial African relative (O. longistaminata) have been released in China.…”

The legacies of the “Father of Hybrid Rice” and the seven representative achievements of Chinese rice research: A pioneering perspective towards sustainable development

“…In addition, owing to the reduction in plowing of perennial rice fields, soil erosion can be reduced, protecting arable land ( Huang et al., 2018 ), and potentially promoting the accumulation of soil organic carbon, mitigating climate change. The commercialized rice was successfully grown on more than 15,000 ha by ~45,000 smallholder farmers in southern China in 2021, contributing to crop productivity, farmer livelihoods, and soil health ( Zhang et al., 2022 ). By leveraging wild rice relatives, perennial rice’s success is inspiring for other crops’ breeding and social, economic, and environmental sustainability ( Crews and Cattani, 2018 ; DeHaan et al., 2020 ; Zhang et al., 2022 ).…”

“…The commercialized rice was successfully grown on more than 15,000 ha by ~45,000 smallholder farmers in southern China in 2021, contributing to crop productivity, farmer livelihoods, and soil health ( Zhang et al., 2022 ). By leveraging wild rice relatives, perennial rice’s success is inspiring for other crops’ breeding and social, economic, and environmental sustainability ( Crews and Cattani, 2018 ; DeHaan et al., 2020 ; Zhang et al., 2022 ).…”