No abstract

Late-season fertilization of bermudagrasses (Cynodon spp. L.C. Rich.) in the transition zone of the United States has traditionally been not recommended. This study was conducted to determine whether late-season fertilization could extend the duration of turfgrass color retention and visual quality without negatively impacting cold tolerance. Field plots of 'Midiron' and 'Tifway' bermudagrasses (C. dactylon 3 C. transvaalensis Burtt Davy), as well as 'Princess-77' and 'Riviera' bermudagrasses [C. dactylon (L.) Pers. var. dactylon] received applications of seaweed extract (SWE) (0.54 kg ha 21 ), N (49 kg ha 21 ), and Fe (1 kg ha 21 ) every 3 wk during the fall of 2001 and 2002.Visual turfgrass assessment showed that cultivar color ratings decreased as the fall progressed, with Princess-77 having greatest color retention in November of both years. Nitrogen was the only treatment to increase turfgrass color ratings relative to the control at the end of each growing season. Stolon samples removed from acclimated plants were artificially frozen to determine freezing tolerance. Midiron displayed the best freezing tolerance followed by Riviera, Tifway, and Princess-77. Chemical treatments did not have a significant effect on shoot regrowth from stolon nodes after freezing. In both years Midiron and Riviera displayed the quickest and greatest amount of spring greenup followed by Tifway and then Princess-77. Cold tolerance indicators proline and linolenic acid were highest in Midiron, followed by Riviera, Tifway, and Princess-77. Nitrogen, SWE, and Fe did not generally have an effect on linolenic acid and no consistent effects of these chemical treatments were noted on proline concentration. The results of this study indicate that judicious N applications during the fall can promote color retention and do not have a negative effect on bermudagrass cold tolerance.

Responses of photosynthesis, Superoxide dismutase activity, and disease tolerance of creeping bentgrass (Agrostis palustris Huds. A.) to soluble potassium silicate (20.8% SiO 2 ) treatments was investigated under two fertilization regimes during 1997 and 1998. Potassium silicate was applied twice a month at 603 and 1205 mL 100 m -2 under high or low fertilization regimes in the field, sampled from which were subjected to low soil moisture in a greenhouse environment. Foliar application of silicate stimulated antioxidant superoxide dismutase (SOD) activity in the bentgarss, especially under the high fertilization regime. Silicate increased photosynthetic capacity (PC) and chlorophyll content when applied at 603 mL 100 m -2 . Dollarspot disease incidence was significantly reduced with silicate treatment regardless of fertilization regime. Silicate did not significantly impact clipping weight. Under low soil moisture (-0.05 MPa), silicate also enhanced SOD activity, PC, and chlorophyll content as well as root mass of bentgrass. Results suggest silicate may be used to enhance turfgrass drought and disease tolerance of turfgrass.

Structural and optical properties of laser deposited ferroelectric (Sr0.2Ba0.8)TiO3 thin films J. Appl. Phys. 79, 7965 (1996); 10.1063/1.362346Electrical properties of SrBi2Ta2O9 thin films and their temperature dependence for ferroelectric nonvolatile memory applications Appl. Phys. Lett. 68, 2300 (1996); 10.1063/1.116170Effects of deposition rate on Bi2Sr2CaCu2O8+x and Bi2Sr1.6La0.4CuO6+x epitaxial thinfilm growth by pulsed laser ablation AIP Conf.

Layered structure SrBi2Ta2O9 thin films were grown on Pt/Ti/Si/SiO2 substrates by laser ablation. The films were deposited at temperatures ranging from 500 to 750 °C and characterized for their phase formation, morphology, surface composition, and ferroelectric properties. Although crystalline phase formation was observed at temperatures as low as 500 °C, well defined saturated hysteresis loops were observed only in films deposited at temperatures of 700 °C or above. The transition in ferroelectric properties between 650 and 700 °C was associated with a change in orientation and grain size. The orientation of the films changed from highly c‐axis oriented at 650 °C to randomly polycrystalline at 700 °C, while the grain size of the films increased from an average value of 80 nm (at 650 °C) to 160 nm (at 700 °C). An understanding of process‐structure relationships is required in order to fabricate high quality films at lower temperatures.