1Department of Crop Sciences, Institute of Grassland Science, Georg-August-University Göttingen.
2Faculty of Life Science, Rhine-Waal University of Applied Sciences, Kleve.
In the next decades, forage legumes are likely to become more important.
However, predicted climate change may increase the risk of droughts and thus
influence their agricultural performance. Decreases in yield due to water shortage are
well documented, while influences on nutritive values are inconsistent. Therefore, we
examined the effects of drought on crude protein (CP), neutral detergent fibre (NDF),
acid detergent fibre (ADF) and water-soluble carbohydrates (WSC) of six legumes,
birdsfoot trefoil (Lotus corniculatus L.); marsh birdsfoot trefoil (Lotus uliginosus
Schkuhr); black medic (Medicago lupulina L.); yellow alfalfa (Medicago falcata L.);
sainfoin (Onobrychis viciifolia Scop.) and white clover (Trifolium repens L.) in
monoculture and in mixture with perennial ryegrass (Lolium perenne L.) in a
container experiment in a vegetation hall. Moderate and strong drought stress was
applied during three periods in two years. Mean volumetric soil water content at the
end of the moderate drought stress period was 11 vol. % and 6 vol. % under strong
stress. The effect of drought on nutritive values was considerably less pronounced
than on yield. While the impact of moderate stress on nutritive quality was
negligible, we found decreases in CP, NDF and ADF and increases in WSC under
strong stress. This may indicate that water scarcity could even increase fodder quality
and digestibility. However, the choice of legume species and stand (monoculture or
mixture) had stronger effects on nutritive values than drought. We conclude that the
reaction of temporary drought on nutritive values seems to be less important for the
selection of suitable forage legumes species than other agronomic properties under
conditions of climate change. Keywords: Crude protein; NDF; ADF; Water-soluble carbohydrates.