Ecotypic variation in forage nutrient value of a dominant prairie grass across a precipitation gradient

Abstract

Ecotypic variation in forage nutrient value of a dominant grassland species, Andropogon gerardii Vitman (big bluestem), was quantified across a longitudinal precipitation gradient of the US Great Plains. Ecotypic variation of A. gerardii has been documented across this gradient, but the extent to which forage nutrient value differs among ecotypes is poorly known. Seven indicators of forage nutrient value (neutral detergent fiber [NDF], acid detergent fiber [ADF], in‐vitro dry matter digestibility [IVDMD], crude protein [CP], crude fat [CF], ash content) and relative feed value [RFV] were examined in 12 populations representing four ecotypes corresponding with distinct climate regions: eastern Colorado, central Kansas, eastern Kansas and southern Illinois. Vegetative material of A. gerardii was collected from each population in July 2010. A greenhouse study tested the effect of watering regime on seedlings of the ecotypes from three of the precipitation regions grown under controlled conditions. Forage nutrient value indicators nitrogen and CP increased, and ADF decreased east to west, while IVDMD decreased across the gradient corresponding with less annual precipitation. The greenhouse experiment showed that sampling before and after water treatment affected forage nutrient value measurements, with the exception of NDF and CF. Nutrient value was most related to soil moisture and phenology, with smaller differences among ecotypes. Nutrient value of populations from the southern Illinois ecotype changed the least in response to variation in soil moisture. The southern Illinois ecotype will likely maintain forge nutrient value under variable precipitation projected to occur with climate change better than the ecotypes from more westerly parts of the range of A. gerardii.

Variation of forage quality traits in Tunisian populations of Brachypodium hybridum in response to phosphorus deficiency

“…Previous studies have demonstrated that the environmental factors including climate and soil fertility have a great effect on the forage quality traits, such as fibers, protein content, and digestibility (Buxton, 1996;Robins et al, 2015). In agreement with our results, the variation in nutritive value traits such IVDMD, ADF, and CP is significantly influenced by monthly and annual precipitation among the populations of the forage grass Andropogon gerardii (Gibson et al, 2016;Mendola et al, 2015). The populations of B. hybridum analyzed in our study span along a precipitation gradient from the north to the south and along gradient of soil salinity and fertility from the coast to the continent.…”

Reciprocal transplant gardens as gold standard to detect local adaptation in grassland species: New opportunities moving into the 21st century

“…Of all common garden designs, reciprocal transplant studies, where populations from spatially separated habitats are cross‐transplanted, have provided some of the most valuable insights into adaptive variation, selection and local adaptation (Savolainen et al., 2013). Numerous studies indicate local adaptation is a common phenomenon that is best investigated with reciprocal transplant platforms (Gibson, Espeland, et al., 2016; Gibson, Donatelli, et al., 2016). This approach is the main focus of this review.…”

The influence of drought stress on yield and forage quality of grasslands differing in functional composition

“…In contrast, drought can also have inconsistent or even negative effects on CP contents, a change that is mostly associated with high drought severity Deleglise et al, 2015Wang & Frei;. Drought is also known to decrease NDF and ADF contents (Bittman et al, 1988;Gibson et al, 2016;, but here, there are also contradicting reports Deleglise et al, 2015;. Drought increases WSC contents .…”

“…Decreasing fibre content during dry periods or under unstable water supply has been reported often (Bittman et al, 1988;Bruinenberg, 2002;Gibson et al, 2016;, although contrary results exist . A decrease is mostly explained by delayed maturation and thus less cell wall material in the physiologically younger plant Küchenmeister et al, 2013), but could also be a result of lacking N supply, because N uptake and thus growth was inhibited under drought .…”

“…Grass-dominated swards are expected to be resilient to drought events . There is evidence that the forage quality of grasses increases if grasses are exposed to drought stress (Fariaszewska et al, 2017;Gibson et al, 2016;.…”