Impact of climate change on the phenological development of winter wheat, sugar beet and winter oilseed rape in Lower Saxony, Germany

There is a general agreement that climate change, in the medium and long term perspective, may affect agricultural crops. As part of the KLIFF project ('Klimafolgenforschung in Niedersachsen', consequences of climatic change in Lower Saxony), the impact of climatic changes on the main crops grown in Lower Saxony (Germany) were analyzed with regard to the potential risks of plant diseases. However, climate does not only affect pathogens and diseases directly, but also the phenological development of the crop plants. In the following paper, the consequences of an increase in temperature in the medium (2020-2050) and long (20702100) term perspective on the appearance of the main phenological stages of wheat, sugar beet and winter oilseed rape were analyzed. In this study, three simulation models were involved that predict the appearance of phenological stages using the date of sowing of the crop and the forecasted temperatures from the climate model REMO-UBA (high resolution regional climate model data) as input data. The results of the simulations for the 3 crops show that an earlier appearance of the phenological stages in both the medium and long term simulation is to be expected. Model calculations indicate a particular shift to an earlier mean appearance of phenological stages of 0.14, 0.13 and 0.44 days year(-1) (mean trend of the regression analysis for the period 1970-2100) for winter wheat, sugar beet and winter oilseed rape, respectively. Such shifts may have significant consequences for the coincidence of susceptible stages of the crop and infective stages of pathogens and may thus cause decreases, increases or balance shifts in the relative importance of individual pathogens in the future, besides the direct climate change effects on diseases. A comparison of the results of this study with available literature data shows, for example, negative consequences for wheat due to the increased risk of infection by leaf rust, tan spot and septoria leaf spot while the risk of infection of powdery mildew remains unchanged. Cercospora leaf spot on sugar beet may appear at an earlier stage of development of the plant, while the risk of Sclerotinia infection for winter oilseed rape is reduced. The advance in phenological stages of crops addressed in this study could have a positive effect on crop yield; however, this effect can be reduced due to the increased risk of diseases, particularly for wheat and sugar beet.