Nickel tolerance in cool‐season grasses

AbstractNickel (Ni) toxicity is becoming more prevalent in plants and soils due to increased use of sewage sludge as fertilizers and wastewater irrigation applications; therefore, research on the tolerance of cool‐season turfgrasses and other grassy species is needed. Annual bluegrass (Poa annua L.) is one of most prevalent annual grassy weeds on fine turf worldwide. This research was conducted to examine Ni tolerance of two creeping bentgrass (Agrostis stolonifera L.) cultivars Seaside II and PennLinks II plus a mixture of annual bluegrass and perennial ryegrass (Lolium perenne L.) grown in pure sand and treated with six different Ni concentration levels supplied as NiSO4·6H2O (control, 200, 400, 800, 1600, and 3200 µg L−1 of Ni). Grasses were assessed based on quality, normalized difference vegetation index (NDVI), relative clipping biomass, relative root biomass, relative total biomass, and plant tissue Ni concentration. All measured parameters decreased, and toxicity symptoms followed by growth reductions were noted for all grasses as Ni concentrations increased. Seaside II and PennLinks II at Ni concentrations of 400 and 800 µg L−1 were noted to be at acceptable turf quality or higher, when weedy species mixture was below the acceptable grass quality level. Seaside II displayed acceptable turf quality even at 1600 µg L−1 of Ni. At 3200 µg L−1 of Ni, PennLinks II and weedy species mixture were necrotic at the conclusion of the 8 weeks of the study compared to Seaside II, which was actively growing with signs of yellowing. Results illustrate genetic differences in Ni tolerance, and Seaside II, a salt‐tolerant creeping bentgrass cultivar, has stronger Ni toxic concentration tolerance than PennLinks II and a mixture of two annual weedy grass species, which are often found in the transition zone. This may explore potentials of more research on micronutrient management of weedy species.