Limited winter survival and compensation mechanisms of yield components constrain winter faba bean production in Central Europe

A substantial deficit of protein sources for livestock and expected changes in agro-climatic conditions are two challenges for European agriculture. Both can be addressed by introducing more autumn-sown legumes into Central European farming systems. Therefore, a three-year field experiment was conducted under Pannonian climate conditions in eastern Austria in which several winter faba bean varieties from different European countries were compared to a spring faba bean variety. Winter faba bean was susceptible to frost damage. Best overwintering was observed with the German variety Hiverna and the French variety Diva. Regarding overwintering, the first winter allowed for a clear differentiation between varieties, in the second winter, severe frost caused loss of almost all winter faba bean plants and in the third winter, which was mild, most varieties showed good overwintering. Grain yield of winter faba bean was mainly determined by variations of plants m^?2 (i.e. by overwintering) whereas compensatory mechanisms between yield components had a minor influence on yield formation. No grain yield advantage could be observed for winter faba bean varieties compared to the spring faba bean variety even in the year with good overwintering. Regarding yield components, winter faba bean had generally more shoots plant^?1 and a higher thousand kernel weight but spring faba bean tended to have more pods shoot^?1 and grains shoot^?1 whereas pods plant^?1, grains plant^?1 and grains pod^?1 generally did not differ. In conclusion, limited winter hardiness together with the minor influence of compensatory mechanisms between yield components on yield formation are serious constraints for increasing the cultivation of winter faba bean in Central Europe.