Ni Toxicity and N Metabolism of Two Warm-Season Turfgrass Species.

Nickel (Ni) is an essential plant mineral micronutrient with a major function to work with urease in hydrolyzing urea being taken up by plants into ammonium before N assimilation.  The optimum range of Ni to turfgrasses and its toxicity levels are poorly understood. To examine the effects of nickel (Ni) toxicity on turfgrass growth and nitrogen metabolism a six week study repeated twice was conducted at the Clemson University greenhouse facility. Two warm season turfgrasses cultivars, ‘Tif-Eagle’ ultradwarf bermudagrass [Cynondon dactylon (L) Pers. X C. transvaalensis Burtt- Davy] and ‘Diamond’ zoysiagrass [Zoysia matrella (L.) Merr.] were established in 85:15 (sand:peat) and subjected to four Ni levels as control, 400, 800, and 1600 µM Ni.  To examine Ni toxicity and influences on N metabolism and growth turfgrass clippings were harvested to measure urease activity, total amino acid content, tissue nutrient concentration, root mass and clipping yield.  At the conclusion of the study, 1600 µM Ni treatments reduced clipping yield by 39%.  Increases in amino acid content and urease activity were exhibited as Ni level increased in leaf tissue, suggesting stimulation of N metabolism.  Results of this research suggest that moderate stimulation of N metabolism by Ni supplementation can be beneficial.  However, as Ni concentration increases in turfgrass leaf tissue, toxicity symptoms are exhibited.  To the authors’ knowledge, this is the first research project examining Ni supplementation and toxicity in turfgrasses.