Root distribution and fibre composition of intergeneric F₁ hybrid between sugarcane and E. arundinaceus

Improving root characteristics is an important breeding target to increase the productivity of sugarcane grown under rainfed conditions. Erianthus arundinaceus is promising breeding material for sugarcane improvement because of its excellent drought tolerance with deep roots. This study evaluated the agronomic traits and root characteristics of an intergeneric F1 hybrid of sugarcane and E. arundinaceus to assess the potential for intro-ducing the root characteristics of E. arundinaceus into sugarcane through intergeneric hybridisation. Field ex-periments using the sugarcane cultivar NiF8, E. arundinaceus clones, and their intergeneric F1 hybrid J08-12, were carried out at the Japan International Research Center for Agricultural Sciences, Japan. We evaluated root distribution from 0 to 120 cm depth and fibre composition, along with agricultural traits, such as biomass productivity, sugar and fibre contents. As was observed with E. arundinaceus clones, J08-12 had more stalks than NiF8 with increased dry matter yield in ratoon crops. The sugar and fibre contents of J08-12 were intermediate between those of NiF8 and E. arundinaceus clones. J08-12 and E. arundinaceus clones had greater root dry matter weight per stool and smaller shoot-root ratios than NiF8. In terms of root distribution, E. arundinaceus clones had significantly greater root dry weights and root length densities than NiF8 from the surface to deep soil layers. J08-12 also exhibited greater root dry weights and root length densities than NiF8, showing significant differ-ences in the 100-120 cm layer in the experiments. Root dry matter and lignin contents were low in NiF8, high in E. arundinaceus clones, and intermediate in J08-12. These results indicate that intergeneric hybridisation of sugarcane and E. arundinaceus could successfully introduce root characteristics of E. arundinaceus, such as deep root distribution and high lignin content, into sugarcane. Improving sugarcane root characteristics through intergeneric hybridisation with E. arundinaceus will be a powerful strategy to improve tolerance to adverse environments and achieve sustainable production in the future.