Perennial cereals for organic agriculture

The cultivation of perennial wheat might represent an economically and ecologically interesting option for extensive cultivation, particularly in marginal land. In autumn 2017, five breeding lines of perennial wheat (Triticum aestivum × Thinopyrum intermedium) and for comparison two varieties of annual wheat were sown at three sites in Bavaria. The five breeding lines were selected from a bulk originating from Washington State University. In 2018, the yield of the perennial breeding lines was 49 to 96 % of the annual cv. ‘Capo’, which reached an average of 17.4 dt/ha. In 2019, the yield was 9 to 38 % of ‘Capo’, which reached an average of 10.8 dt/ha, showing large differences between the locations. The autumn re-emergence was significantly affected by the severe drought at all sites in 2018 and 2019 and showed differences between the lines up to a total failure at one site. In the third year, the yield of the breeding lines was very low, thus a third year of cultivation cannot be recommended under these climatic and soil conditions. The yields of the plots with under-sown clover were significantly higher in the third year. A mixture with a low growing clover species is recommended because of better weed suppression. Field trials in Austria with perennial rye cv. ‘Perenne’ derived from an interspecific cross between Secale cereale and S. montanum were carried out from 2012 to 2015 in order to determine biomass yield and regrowth capability. Biomass yield of ‘Perenne’ in the early cuttings was between 70 and 95% compared to cv. ‘Elego’, but decreased to 45% after heading/anthesis for the two- and three-year crop stand. This decrease was mainly due to the reduced plant height (-45 cm) of the perennial crop in the 2nd and 3rd year compared to the first year crop. Root mass in the three-year crop was significantly higher compared to ‘Elego’ and the first and second year ‘Perenne’, but mainly only in the top 20 cm. Generally, significantly inferior grain yield was obtained for ‘Perenne’, reaching only 53%, 26% and 15% for the 1st, 2nd and 3rd year crop, respectively, compared to annual ‘Elego’ (5670 kg/ha). Similarly, a significant decrease was also observed for thousand grain weight (-32%) from the first to the third year of cultivation. Moreover, a higher number of ergot sclerotia was observed for the interspecific perennial rye hybrid compared to ‘Elego’. Weed infestation was constantly increasing in the perennial crop making a cultivation of more than 3 years not recommendable