Mineral concentrations in four tropical forages as affected by increasing daylength. I. Macrominerals^*

Abstract

Pure stands of the following four grasses Florakirk and Tifton 85 bermudagrass [Cynodon dactylon (L) Pers.], Florona stargrass (Cynodon nlemfuensis Vanderyst), and Pensacola bahiagrass (Paspalum notatum Fluegge) were established in central Florida. Individual grass plots were exposed to two daylength treatments, extended (artificial light used to maintain daylength at 15 h) and normal daylength conducted over a two-year period. Samples were harvested at distances of 4.0 m>behind=the light and 1.0 m>in front=of the light. Samples were collected and analyzed for calcium (Ca), phosphorus (P), magnesium (Mg), potassium (K), and sodium (Na) at six sample dates from the late fall to early spring for two consecutive years. Forage Ca decreased with extended daylength (from 0.39 to 0.36%). There was no significant difference between normal and extended daylength for P, Mg, K, and Na. Forage Ca concentrations decreased with extended daylength for Florakirk bermudagrass and Pensacola bahiagrass (from 0.40 to 0.36% and from 0.32 to 0.27%, respectively). Florakirk bermudagrass had the highest mean concentrations of P (0.38%). Florona stargrass had the highest mean concentrations of Ca (0.44%). Pensacola bahiagrass had the highest mean concentrations of Na (0.027%). Tifton-85 bermudagrass had the highest mean concentrations of Mg (0.21%). Forage Na concentrations were below the requirements for grazing cattle, but this is typical for central Florida. The extended daylength in this experiment did not have a practical difference on the concentrations of the five macrominerals. Only Na concentration increased with an extended daylength for Pensacola bahiagrass, however, this was still insufficient to meet the requirements for beef cattle. Calcium, P, and K concentrations of these four forages met the requirements for beef cattle.

^*Florida Agricultural Experiment Station Journal Series No. R-08262.

Acknowledgments

Notes

^*Florida Agricultural Experiment Station Journal Series No. R-08262.