— 37 IREC Farmers' Newsletter No. 200 — Spring 2018 The F1 hybrid showed very rapid seedling growth compared to both parents, with faster shoot elongation and 100% greater leaf area development at 20 days after sowing (Figure 1a). The hybrid also had a greater number of tillers before panicle initiation than either parent (Figure 1b). Hybrid plants were visibly larger in size at all growth stages. The F1 hybrid was significantly later to flower that either parent. At maturity, the F1 hybrid plants were taller and had more biomass than either parent (72% more than Doongara and 66% more than Reiziq, Figure 1c) and greater grain weight than either parent (57% more than Doongara and 35% more than Reiziq, Figure 1d). The photograph on the previous page shows example plants for the F1 hybrid and each parent during grain filling. Figure 1. Hybrid rice outperformed both parents for a range of characteristics, including seedling leaf area (a), tillers at 40 days after sowing (b), harvest biomass (c) and harvest grain weight (d). The bars show Best Linear Unbiased Estimates with 95% confidence interval. Hybrid vigour in Australian rice Our results demonstrate clear evidence of substantial hybrid vigour in Australian rice. The significantly higher biomass accumulation and grain weight in the F1 hybrid are consistent with other reported results from much larger experimental and commercial comparisons showing hybrid rice has a significant yield and biomass advantage over the inbreeding hybrid parents. Cultivated rice has two subspecies—indica and japonica. We used two japonica parents for our hybrid, in contrast to some hybrid production systems that use genetically wider crosses between the two subspecies. We combined the — 37 IREC Farmers' Newsletter No. 200 — Spring 2018 Prospects for hybrid rice