Drought Effects on Yield and Quality of Perennial Grasses in the North Central United States

Abstract

Drought frequently limits perennial grass productivity during midsummer in the North Central States, yet the relative drought tolerance of perennial grasses grown in this region is unknown. We determined the effect of water deficit (drought) on the forage yield, forage quality, and stand persistence of reed canarygrass (Phalaris arundinacea L.), smooth bromegrass (Bromus inermis Leyss.), orchardgrass (Dactylis glomerata L.), and timothy (Phleum pratense L.). Grasses were grown on a Hubbard loamy sand (sandy, mixed, Udorthentic Haploboroll) and subjected to two soil-water regimes simulating ‘droughted’ and ‘well-watered’ (control) plant growth. When drought occurred throughout the regrowth cycle, forage yields of droughted reed canarygrass, orchardgrass, smooth bromegrass, and timothy were 33, 37, 24, and 34%, respectively, of the controls. Reed canarygrass yields under drought were similar to those of orchardgrass but greater than those of timothy and smooth bromegrass. Total season yields of reed canarygrass, orchardgrass, smooth bromegrass, and timothy exposed to periods of drought followed by well-watered conditions were 54, 60, 81, and 62%, respectively, of the irrigated controls, which suggests that smooth bromegrass may be capable of compensatory growth following drought. Drought consistently enhanced the leafiness of reed canarygrass, smooth bromegrass, and timothy, which have a culmed growth habit (i.e., stem elongation during all regrowths). When drought occurred throughout growth, crude protein concentration of leaf, stem, and total forage of all species was greater than the controls. Drought decreased neutral and acid detergent fiber (NDF and ADF) concentrations in total forage of reed canarygrass and smooth bromegrass at all harvests and of orchardgrass and timothy at two of three harvests. Enhanced forage quality was associated with increased forage leafiness and enhanced stem and leaf quality. Drought reduced the persistence of reed canarygrass and timothy compared with the control, but had no effect on smooth bromegrass or orchardgrass persistence. Smooth bromegrass was the most persistent and orchardgrass was the least persistent grass. Our results indicate that reed canarygrass is among the most productive cool-season grasses during drought. Smooth bromegrass, however, may have greater long-term yield and persistence than other cool-season grasses under the typical pattern of favorable spring moisture and midsummer drought in the North Central States.