A study of the vernalization requirements of mountain rye (Secale strictum syn. S. montanum) may help explain low grain yields of perennial cereals compared to wheat.

Mountain rye (MR: Secale strictum syn. S. montanum) is a forage grass that is considered a candidate for perennial grain development in Australia. A greater understanding of the triggers for flowering would aid the integration of this dual-purpose perennial into Australian grazing and cropping systems. The objective of this experiment was to determine the effects of cold incubation (vernalization) periods of varying duration on the grain yield, biomass production, and phenology of MR, compared to a dual purpose annual winter wheat cultivar (AW: Triticum aestivum L), and the perennial intermediate wheatgrass (IWG: Thinopyrum intermedium (Host) Barkworth & D.R. Dewey). Plants were grown in pots to a three leaf stage, before being subjected to vernalization treatments of varying length (0, 3, 5, 7, 9, and 11 weeks) using a growth chamber set to 5°C and 10 hour lighting. The plants were then transferred to a glasshouse set to 22°C and a minimum of 10 hour lighting. Glasshouse daylengths increased as the season progressed from winter into spring and summer. Exposure at ≤5°C for 5 weeks in MR optimized reproductive development, compared to approximately 3 weeks for winter wheat and 11 weeks for IWG. Both MR and IWG appear to have a dual induction requirement, needing a period of cold exposure and short days, followed by daylengths of 12-13 hours for MR, and at least 13 hours for IWG, to optimize their grain production potential. The observed higher vernalization requirement of MR, compared to AW, helps delineate the grain production potential of the tested germplasm in current wheat-growing areas of temperate Australia. Reproductive tiller percentages were much higher and developed earlier in AW compared to the perennial cereals. Improving the ratio and timing of reproductive tillers development in perennial cereals should be a target if grain yields are to be improved.