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  • Author or Editor: J.D. Fry x
  • Journal of the American Society for Horticultural Science x
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Abstract

Little research has been conducted to determine the influence of fertilizer sources and rates on zoysiagrass (Zoysia japonica Steud.) establishment. Our objectives were to determine the influence of slow-release N sources, water-soluble N from urea, and N, P, and K combinations on rate of zoysiagrass establishment. Prior to field planting of zoysiagrass plugs, N rates of 98, 196, and 392 kg·ha-1 from ureaformaldehyde (UF, 38N-0P-0K), isobutylidine diurea (IBDU, 31N-0P-0K, and a composted sewage sludge (1.0N-0.9P-0.2K) were incorporated into a soil with existing high P (193 kg·ha-1) and intermediate K levels (86 kg·ha-1). In a separate study nitrogen from urea (46N-0P-0K, 195 kg·ha-1), P from treble superphosphate (0N-19P-0K, 126 kg·ha-1) and K from muriate of potash (0N-0P-32K, 103 kg·ha-1) also were incorporated before planting. Five months after planting, none of the slow-release N sources or N-P-K combinations had enhanced coverage of the zoysiagrass. No additional fertilizer was applied in the 2nd year. Although statistically significant differences were found among treatments by the end of the 2nd growing season, the actual increases in zoysiagrass coverage provided by the fertilizers were no greater than 5% more than the unfertilized zoysiagrass. In a 3rd study, N (49 kg·ha-1) from urea, applied as a topdressing either once, four, or seven times annually, resulted in a negative linear [coverage = 63.8 − 0.02 (kg N/ha per year), r 2 = 0.57] response in zoysiagrass coverage the initial year, but not in the 2nd year. Nitrogen from urea (49 kg·ha-1) applied bimonthly or monthly the 2nd year had a greater beneficial effect on zoysiagrass growth than topdressing or preplant incorporation of N the initial year.

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Little is known about intraspecific variability in St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] freezing tolerance and the physiological factors that may influence survival. Stolons of field-grown `Raleigh', `Floratam', and FX-332 St. Augustinegrass were sampled between October and March in 1990 to 1991 and 1991 to 1992 to measure freezing tolerance, nonstructural carbohydrates, and water content. Stolons were exposed to temperatures between 1 and -8C in a freezer, and regrowth was evaluated in the greenhouse. Generally, freezing tolerance of `Raleigh' > `Floratam' = FX-332. `Raleigh' exhibited >60% survival in December and January, while survival of `Floratam' and FX-332 was <20%. `Raleigh' was the only cultivar that acclimated, as indicated by a 75% increase in survival between October and December 1990. Starch and sucrose were the primary storage carbohydrates extracted from stolons, but neither was correlated with freezing tolerance. A negative (r = -0.80) correlation was observed between `Raleigh' survival and stolon water content between January and March 1991. Reduced water content in `Raleigh' stolons during winter months may contribute to acclimation.

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