Variability in zinc content in different grass species and red clover

Abstract

In 1997 on seven different plots of the same ground in four periods and in different stages of growth in each period ten samples of red clover (Trifolium pratense) and Italian ryegrass (Lolium multiflorum) and eight samples of timothy (Phleum pratense), perennial ryegrass (Lolium perenne), meadow fescue (Festuca pratensis), red fescue (Festuca rubra) and orchardgrass (Dactylis glomerata) were collected. In the soil sample the pH value of 7.2 and 75.8 mg zinc kg^-1 were established. On the average grass samples contained 20.36 mg and red clover 26.43 mg zinc kg^-1 DM. The lowest zinc concentration was found in samples of red fescue (16.92 mg kg^-1 DM). In perennial ryegrass the zinc content was 18.13 mg, in meadow fescue 18.66 mg and in orchard grass 20.84 mg kg^-1 DM. The highest value was found in timothy (23.66 mg kg^-1 DM) and in Italian ryegrass (23.77 mg kg^-1 DM). Differences between grasses were statistically significant. In the first harvest a statistically significant change in zinc concentration with maturity of plants was demonstrated (22.44 mg, 19.57 mg and 16.47 mg kg^-1 DM for vegetative, heading and flowering stage of growth respectively). Between zinc concentrations in samples of first harvest and of second harvest there were no significant differences (19.49 mg and 20.22 mg kg^-1 DM, respectively). In samples collected in the third harvest zinc concentration was higher (24.29 mg kg^-1 DM), P< 0.05) than in first and second harvest. The highest value was found in samples of the autumn harvest (26.91 mg kg^-1 DM, P< 0.05). Differences between zinc concentrations in timothy, perennial ryegrass and Italian ryegrass samples collected in the first harvest and in autumn harvest were very high (+78.4%, +68.0% and +58.4%, respectively).