Exceptionally high fertility observed in three F1 hybrids between Lolium multiflorum Lam. and L. temulentum L.

Abstract

AbstractThe pollen fertility and seed set of three F1 hybrid plants derived from a cross between a darnel ryegrass (Lolium temulentum L.) line (Ba3081) and a genotype of Italian ryegrass (L. multiflorum Lam.) were evaluated in field and greenhouse experiments under different temperatures. In the field where the daily mean temperature for 3 weeks prior to pollen dispersal was 16.5°C, the mean pollen fertility of the F1 plants was 42.8%, which was lower than the value observed in the parental species (96.0–98.1%). In two greenhouses with a daily mean temperature of 20.4 and 15.8°C, the mean pollen fertility of the F1 plants was 53.1% and 44.0%, respectively, which were higher than the values reported previously for the hybrids between L. temulentum × L. multiflorum (maximum of about 20%). The seed set of the F1 plants was 24% under open‐pollinated conditions in the field compared with 4.2–8.8% under self‐pollinated conditions in the two greenhouses. These results indicated that the F1 plants were self‐fertile and able to set F2 seed, with a significant reduction in pollen fertility occurring with a decrease in the daily mean temperature (2.15% decrease in fertility per unit decrease in temperature). The germination rate of the F2 seeds was approximately 57%, indicating the possibility of producing an F2 population for future genetic analysis. This is the first report of F1 plants from L. temulentum × L. multiflorum with fertile pollen and with the ability to produce progeny by self‐pollination. These findings suggest a possibility of developing recombinant inbred lines between L. temulentum and L. multiflorum.